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Polymers, Volume 15, Issue 7 (April-1 2023) – 218 articles

Cover Story (view full-size image): The measure of the refractive index and its chromatic dispersion in dielectric thin films is fundamental for applications ranging from optics to biotechnology and metrology. Reliable and accurate measurements typically require expensive equipment and specialized expertise, relegating the analysis to specialized laboratories. In this study, a new accessible method for the measurement of the refractive index is proposed. The core of our refractometer is the use of a simple theoretical model, based on the scalar theory of light diffraction, to estimate the refractive index of a moldable material, replicating diffraction grating on its surface, from simple optical and topographic measurements. View this paper
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16 pages, 17061 KiB  
Article
Optimization of Gel Flooding during the High Water Cut Stage in a Conglomerate Reservoir of the Xinjiang A Oilfield
by Xiankang Xin, Qian Liu, Saijun Liu, Gaoming Yu and Qingshan Wan
Polymers 2023, 15(7), 1809; https://doi.org/10.3390/polym15071809 - 06 Apr 2023
Cited by 2 | Viewed by 1262
Abstract
Influenced by water injection, a dominant flow channel is easily formed in the high water cut stage of a conglomerate reservoir, resulting in the inefficient or ineffective circulation of the injected water. With gel flooding as one of the effective development methods to [...] Read more.
Influenced by water injection, a dominant flow channel is easily formed in the high water cut stage of a conglomerate reservoir, resulting in the inefficient or ineffective circulation of the injected water. With gel flooding as one of the effective development methods to solve the above problems, its parameter optimization determines its final development effect, which still faces great challenges. A new optimization method for gel flooding is proposed in this paper. Firstly, the gel flooding parameters were obtained through physical experiments; then, an experimental model of gel flooding was established according to the target reservoir, and parameter sensitivity analysis was carried out. Next, a history matching of the gel flooding experiment was carried out. Finally, history matching of the target reservoir was also carried out, and a gel flooding scheme was designed and optimized to determine the best parameters. The experimental results showed that the gelation time was 4 h and the gel viscosity was 6332 mPa·s; the breakthrough pressure, resistance factor (RF), and residual resistance factor (RRF) all decreased with the increase in permeability. The gel had a good profile control ability and improved oil recovery by 16.40%. The numerical simulation results illustrated that the porosity of the high permeability layer (HPL) had the greatest impact on the cumulative oil production (COP) of the HPL, and the maximum polymer adsorption value of the HPL had the largest influence on the COP of the low permeability layer (LPL) and the water cut of both layers. Benefiting from parameter sensitivity analysis, history matching of the gel flooding experiment and a conglomerate reservoir in the Xinjiang A Oilfield with less time consumed and good quality was obtained. The optimization results of gel flooding during the high water cut stage in a conglomerate reservoir of the Xinjiang A Oilfield were as follows: the gel injection volume, injection rate, and polymer concentration were 2000 m3, 50 m3/d, and 2500 mg/L, respectively. It was predicted that the water cut would decrease by 6.90% and the oil recovery would increase by 2.44% in two years. This paper not only provides a more scientific and efficient optimization method for gel flooding in conglomerate reservoirs but also has important significance for improving the oil recovery of conglomerate reservoirs. Full article
(This article belongs to the Section Polymer Applications)
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14 pages, 2344 KiB  
Article
Ligand Installation to Polymeric Micelles for Pediatric Brain Tumor Targeting
by Takayoshi Watanabe, Hayato Laurence Mizuno, Jumpei Norimatsu, Takumi Obara, Horacio Cabral, Kouhei Tsumoto, Makoto Nakakido, Daisuke Kawauchi and Yasutaka Anraku
Polymers 2023, 15(7), 1808; https://doi.org/10.3390/polym15071808 - 06 Apr 2023
Cited by 1 | Viewed by 2114
Abstract
Medulloblastoma is a life-threatening disease with poor therapeutic outcomes. In chemotherapy, low drug accumulation has been a cause of these outcomes. Such inadequate response to treatments has been associated with low drug accumulation, particularly with a limited cellular uptake of drugs. Recently, the [...] Read more.
Medulloblastoma is a life-threatening disease with poor therapeutic outcomes. In chemotherapy, low drug accumulation has been a cause of these outcomes. Such inadequate response to treatments has been associated with low drug accumulation, particularly with a limited cellular uptake of drugs. Recently, the conjugation of drugs to ligand molecules with high affinity to tumor cells has attracted much attention for enhancing drug internalization into target cells. Moreover, combining tumor-targeting ligands with nano-scaled drug carriers can potentially improve drug loading capacity and the versatility of the delivery. Herein, we focused on the possibility of targeting CD276/B7-H3, which is highly expressed on the medulloblastoma cell membrane, as a strategy for enhancing the cellular uptake of ligand-installed nanocarriers. Thus, anti-CD276 antibodies were conjugated on the surface of model nanocarriers based on polyion complex micelles (PIC/m) via click chemistry. The results showed that the anti-CD276 antibody-installed PIC/m improved intracellular delivery into CD276-expressing medulloblastoma cells in a CD276-dependent manner. Moreover, increasing the number of antibodies on the surface of micelles improved the cellular uptake efficiency. These observations indicate the potential of anti-CD276 antibody-installed nanocarriers for promoting drug delivery in medulloblastoma. Full article
(This article belongs to the Special Issue Polymers for Cancer Therapy and Diagnostics)
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10 pages, 5443 KiB  
Article
Time–Concentration Superposition for Linear Viscoelasticity of Polymer Solutions
by Can-Qi Li, Horst Henning Winter, Yuan-Qi Fan, Geng-Xin Xu and Xue-Feng Yuan
Polymers 2023, 15(7), 1807; https://doi.org/10.3390/polym15071807 - 06 Apr 2023
Viewed by 2175
Abstract
The concentration dependence of linear viscoelastic properties of polymer solutions is a well-studied topic in polymer physics. Dynamic scaling theories allow qualitative predictions of polymer solution rheology, but quantitative predictions are still limited to model polymers. Meanwhile, the scaling properties of non-model polymer [...] Read more.
The concentration dependence of linear viscoelastic properties of polymer solutions is a well-studied topic in polymer physics. Dynamic scaling theories allow qualitative predictions of polymer solution rheology, but quantitative predictions are still limited to model polymers. Meanwhile, the scaling properties of non-model polymer solutions must be determined experimentally. In present paper, the time–concentration superposition (TCS) of experimental data is shown to be a robust procedure for studying the concentration scaling properties of binary and ternary polymer solutions. TCS can not only identify whether power law scaling may exist or not, and over which concentration range, but also unambiguously estimate the concentration scaling exponents of linear viscoelastic properties for a range of non-model polymer solutions. Full article
(This article belongs to the Special Issue Advances in Rheology of Polymers)
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13 pages, 1656 KiB  
Article
Evolution of the Viscoelastic Properties of Filler Reinforced Rubber under Physical Aging at Room Temperature
by María Vizcaíno-Vergara, Leif Kari, Lewis B. Tunnicliffe and James J. C. Busfield
Polymers 2023, 15(7), 1806; https://doi.org/10.3390/polym15071806 - 06 Apr 2023
Viewed by 1283
Abstract
Filler reinforced rubber is widely used for engineering applications; therefore, a sound characterization of the effects of physical aging is crucial for accurately predicting its viscoelastic properties within its operational temperature range. Here, the torsion pendulum is used to monitor the evolution of [...] Read more.
Filler reinforced rubber is widely used for engineering applications; therefore, a sound characterization of the effects of physical aging is crucial for accurately predicting its viscoelastic properties within its operational temperature range. Here, the torsion pendulum is used to monitor the evolution of the storage and loss modulus of carbon black filled samples for four days after a temperature drop to 30 °C. The storage modulus presents a continuous increase, while the loss modulus generally displays a steady decrease throughout the four days that each test was conducted. The relationship of the recovery rates with the carbon black properties is also studied, analysing its dependency on the particle size and aggregate structure. The evolution of the recovery rate seems to depend linearly on the surface area while the carbon black structure appears to have a much weaker influence on the physical aging behavior for the set of compounds tested. The obtained results corroborate the presence of physical aging at room temperature for filler rubber materials and the ability of the torsion pendulum to monitor the storage and loss modulus change, providing pivotal data on the influence of physical aging on the viscoelastic properties of the material. Full article
(This article belongs to the Special Issue Physical Aging of Polymers)
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15 pages, 3185 KiB  
Article
Modelling across Multiple Scales to Design Biopolymer Membranes for Sustainable Gas Separations: 1—Atomistic Approach
by Kseniya Papchenko, Eleonora Ricci and Maria Grazia De Angelis
Polymers 2023, 15(7), 1805; https://doi.org/10.3390/polym15071805 - 06 Apr 2023
Cited by 3 | Viewed by 1239
Abstract
In this work, we assessed the CO2 and CH4 sorption and transport in copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), which showed good CO2 capture potential in our previous papers, thanks to their good solubility–selectivity, and are potential biodegradable alternatives to [...] Read more.
In this work, we assessed the CO2 and CH4 sorption and transport in copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), which showed good CO2 capture potential in our previous papers, thanks to their good solubility–selectivity, and are potential biodegradable alternatives to standard membrane-separation materials. Experimental tests were carried out on a commercial material containing 8% of 3-hydroxyvalerate (HV), while molecular modelling was used to screen the performance of the copolymers across the entire composition range by simulating structures with 0%, 8%, 60%, and 100% HV, with the aim to provide a guide for the selection of the membrane material. The polymers were simulated using molecular dynamics (MD) models and validated against experimental density, solubility parameters, and X-ray diffraction. The CO2/CH4 solubility–selectivity predicted by the Widom insertion method is in good agreement with experimental data, while the diffusivity–selectivity obtained via mean square displacement is somewhat overestimated. Overall, simulations indicate promising behaviour for the homopolymer containing 100% of HV. In part 2 of this series of papers, we will investigate the same biomaterials using a macroscopic model for polymers and compare the accuracy and performance of the two approaches. Full article
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19 pages, 5874 KiB  
Article
Polyaniline-Supported Nickel Oxide Flower for Efficient Nitrite Electrochemical Detection in Water
by Nada S. Al-Kadhi, Mahmoud A. Hefnawy, Fowzia S. Alamro, Rami Adel Pashameah, Hoda A. Ahmed and Shymaa S. Medany
Polymers 2023, 15(7), 1804; https://doi.org/10.3390/polym15071804 - 06 Apr 2023
Cited by 14 | Viewed by 1840
Abstract
A modified electrode with conducting polymer (Polyaniline) and NiO nanoflowers was prepared to detect nitrite ions in drinking water. A simple method was used to prepare the NiO nanoflower (NiOnF). Several techniques characterized the as-prepared NiOnF to determine the chemical structure and surface [...] Read more.
A modified electrode with conducting polymer (Polyaniline) and NiO nanoflowers was prepared to detect nitrite ions in drinking water. A simple method was used to prepare the NiO nanoflower (NiOnF). Several techniques characterized the as-prepared NiOnF to determine the chemical structure and surface morphology of the NiO, such as XRD, XPS, FT-IR, and TGA. The activity of the electrode toward nitrite sensing was investigated over a wide range of pH (i.e., 2 to 10). The amperometry method was used to determine the linear detection range and limit. Accordingly, the modified electrode GC/PANI/NiOnf showed a linear range of detection at 0.1–1 µM and 1–500 µM. At the same time, the limit of detection (LOD) was 9.7 and 64 nM for low and high concentrations, respectively. Furthermore, the kinetic characteristics of nitrite, such as diffusion and transport coefficients, were investigated in various media. Moreover, the charge transfer resistance was utilized for nitrite electrooxidation in different pH values by the electrochemical impedance technique (EIS). The anti-interfering criteria of the modified surfaces were utilized in the existence of many interfering cations in water (e.g., K+, Na+, Cu2+, Zn2+, Ba2+, Ca2+, Cr2+, Cd2+, Pd2+). A real sample of the Nile River was spiked with nitrite to study the activity of the electrode in a real case sample (response time ~4 s). The interaction between nitrite ions and NiO{100} surface was studied using DFT calculations as a function of adsorption energy. Full article
(This article belongs to the Special Issue Nanopolymers and Nanocomposites)
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11 pages, 4777 KiB  
Article
Cd(II)/Mn(II)/Co(II)/Ni(II)/Zn(II) Coordination Polymers Built from Dicarboxylic Acid/Tetracarboxylic Acid Ligands: Their Structural Diversity and Fluorescence Properties
by Lu Liu, Jian-Min Li, Meng-Di Zhang, Hui-Jie Wang, Ying Li, Zhen-Bei Zhang, Zi-Fang Zhao, Yu Xi, Yuan-Yuan Huang, Jie Xu, Bo Zhang, Jun Chen and Cheng-Xing Cui
Polymers 2023, 15(7), 1803; https://doi.org/10.3390/polym15071803 - 06 Apr 2023
Viewed by 1153
Abstract
Six Cd(II)/Mn(II)/Co(II)/Ni(II)/Zn(II) coordination complexes are formulated as [Cd2(X2−)2(μ3-O)2/3]n (1), [Mn2(X2−)2(μ3-O)2/3]n (2), {[Co1.5(Y4− [...] Read more.
Six Cd(II)/Mn(II)/Co(II)/Ni(II)/Zn(II) coordination complexes are formulated as [Cd2(X2−)2(μ3-O)2/3]n (1), [Mn2(X2−)2(μ3-O)2/3]n (2), {[Co1.5(Y4−)0.5(4,4′-bpy)1.5(OH)]·2H2O}n (3), {[Ni(X2−)(4,4′-bpy)(H2O)2]·4H2O}n (4), [Zn(m-bdc2−)(bebiyh)]n (5), and [Cd(5-tbia2−)(bebiyh)]n (6) (H2X = 3,3′-(2,3,5,6-tetramethyl-1,4-phenylene) dipropionic acid. H4Y = 2,2′-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene) dimalonic acid, bebiyh = 1,6-bis(2-ethyl-1H-benzo[d]imidazol-1-yl)hexane, m-H2bdc = 1,3-benzenedicarboxylic acid, and 5-H2tbia = 5-(tert-butyl)isophthalic acid) were obtained by hydrothermal reactions and structurally characterized. Complexes 1 and 2 have a 6-connected 3D architecture and with several point symbols of (36·46·53). Complex 3 features a 5-connected 3D net structure with a point symbol of (5·69). Complex 4 possesses a 4-connected 2D net with a vertex symbol of (44·62). Complex 5 is a 3-connected 2D network with a point symbol of (63). Complex 6 is a (3,3)-connected 2D network with a point symbol of (63)2. In addition, complexes 1 and 4 present good photoluminescence behaviors. The electronic structures of 1 and 4 were investigated with the density functional theory (DFT) method to understand the photoluminescence behaviors. Full article
(This article belongs to the Special Issue Coordination Polymers: Properties and Applications II)
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21 pages, 6009 KiB  
Article
Investigation on Properties of Raw and Alkali Treated Novel Cellulosic Root Fibres of Zea Mays for Polymeric Composites
by S. Anne Kavitha, R. Krishna Priya, Krishna Prakash Arunachalam, Siva Avudaiappan, Nelson Maureira-Carsalade and Ángel Roco-Videla
Polymers 2023, 15(7), 1802; https://doi.org/10.3390/polym15071802 - 06 Apr 2023
Cited by 17 | Viewed by 1836
Abstract
Today, new materials based on natural fibres have been emerging day by day to completely eradicate plastics to favour our environmental nature. In this view, the present work is based on the extraction and characterisation of the novel root fibres of the Zea [...] Read more.
Today, new materials based on natural fibres have been emerging day by day to completely eradicate plastics to favour our environmental nature. In this view, the present work is based on the extraction and characterisation of the novel root fibres of the Zea mays (Zm) plant, grown by the hydroponic method. Both the dried untreated and alkali treated root fibres are investigated using a variety of structural, morphological, thermal, elemental and mechanical tests by subjecting both the samples to p-XRD, FT-IR, SEM-EDAX, TGA-DTA, CHNS and tensile strength analyses. Thermal conductivity of the untreated and treated fibres is found using Lee’s disc experiment. From p-XRD analysis, the Crystallinity Index, Percentage Crystallinity and Crystallite size of the samples are found. FT-IR studies clarify the different vibrational groups associated with the fibre samples. SEM images show that the surface roughness increases for the chemically treated samples, such that it may be effectively utilised as reinforcement for polymeric composites. The diameter of the fibre samples is found using SEM analysis. According to the EDAX spectrum, Zm fibres in both their raw and processed forms have high levels of Carbon (C) and Oxygen (O). The TGA-DTA tests revealed that the samples of natural fibre have good thermal characteristics. CHNS studies show that Carbon content is high for these samples, which is the characteristic of many natural fibres. Chemical analysis is used to ascertain the prepared samples’ chemical makeup. It reveals that both samples have significant amounts of cellulose. The density of the fibres is found to be in the range 0.3–0.6 g/cc, which is much less than any other natural fibre. Therefore, it can be used in light weight applications. From the tensile strength analysis, physical properties such as Young’s modulus and micro-fibril angle are determined. The fibres in the roots exhibit a lower tensile strength. Thus, these fibres can be used in powdered form as reinforcement for natural rubber or epoxy composites. After examining all of its properties, it could be reasonably speculated that Zea mays root fibres can be considered as an efficient reinforcement for various matrices to produce attractive bio-composites. Full article
(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites)
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32 pages, 2540 KiB  
Review
Microbial Exopolysaccharide Composites in Biomedicine and Healthcare: Trends and Advances
by Vishal Ahuja, Arvind Kumar Bhatt, J. Rajesh Banu, Vinod Kumar, Gopalakrishnan Kumar, Yung-Hun Yang and Shashi Kant Bhatia
Polymers 2023, 15(7), 1801; https://doi.org/10.3390/polym15071801 - 06 Apr 2023
Cited by 14 | Viewed by 4450
Abstract
Microbial exopolysaccharides (EPSs), e.g., xanthan, dextran, gellan, curdlan, etc., have significant applications in several industries (pharma, food, textiles, petroleum, etc.) due to their biocompatibility, nontoxicity, and functional characteristics. However, biodegradability, poor cell adhesion, mineralization, and lower enzyme activity are some other factors that [...] Read more.
Microbial exopolysaccharides (EPSs), e.g., xanthan, dextran, gellan, curdlan, etc., have significant applications in several industries (pharma, food, textiles, petroleum, etc.) due to their biocompatibility, nontoxicity, and functional characteristics. However, biodegradability, poor cell adhesion, mineralization, and lower enzyme activity are some other factors that might hinder commercial applications in healthcare practices. Some EPSs lack biological activities that make them prone to degradation in ex vivo, as well as in vivo environments. The blending of EPSs with other natural and synthetic polymers can improve the structural, functional, and physiological characteristics, and make the composites suitable for a diverse range of applications. In comparison to EPS, composites have more mechanical strength, porosity, and stress-bearing capacity, along with a higher cell adhesion rate, and mineralization that is required for tissue engineering. Composites have a better possibility for biomedical and healthcare applications and are used for 2D and 3D scaffold fabrication, drug carrying and delivery, wound healing, tissue regeneration, and engineering. However, the commercialization of these products still needs in-depth research, considering commercial aspects such as stability within ex vivo and in vivo environments, the presence of biological fluids and enzymes, degradation profile, and interaction within living systems. The opportunities and potential applications are diverse, but more elaborative research is needed to address the challenges. In the current article, efforts have been made to summarize the recent advancements in applications of exopolysaccharide composites with natural and synthetic components, with special consideration of pharma and healthcare applications. Full article
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13 pages, 7600 KiB  
Article
Modification of Polyamide 66 for a Media-Tight Hybrid Composite with Aluminum
by Fabian Lins, Christian Kahl, Jan-Christoph Zarges and Hans-Peter Heim
Polymers 2023, 15(7), 1800; https://doi.org/10.3390/polym15071800 - 06 Apr 2023
Viewed by 1180
Abstract
Metal–plastic composites are becoming increasingly important in lightweight construction. As a combination, e.g., for transmission housings in automobiles, composites made of die-cast aluminum housings and Polyamide 66 are a promising material. The interface between metal and plastic and the properties of the plastic [...] Read more.
Metal–plastic composites are becoming increasingly important in lightweight construction. As a combination, e.g., for transmission housings in automobiles, composites made of die-cast aluminum housings and Polyamide 66 are a promising material. The interface between metal and plastic and the properties of the plastic component play an important role with regard to media tightness against transmission oil. The mechanical properties of the plastic can be matched to aluminum by glass fibers and additives. In the case of fiber-reinforced plastics, the mechanical properties depend on the fiber length and their orientation. These structural properties were investigated using computer tomography and dynamic image analysis. In addition to the mechanical properties, the thermal expansion coefficient was also investigated since a strongly different coefficient of the joining partners leads to stresses in the interface. Polyamide 66 was processed with 30 wt% glass fibers to align the mechanical and thermal expansion properties to those of aluminum. In contrast to the reinforcement additives, an impact modifier to improve the toughness of the composite, and/or a calcium stearate to exert influence on the rheological behavior of the composite, were used. The combination of the glass fibers with calcium stearate in Polyamide 66 led to high stiffnesses (11,500 MPa) and strengths (200 MPa), which were closest to those of aluminum. The coefficient of thermal expansion was found to be 6.6 × 10−6/K for the combination of Polyamide 66 with 30 wt% glass fiber and shows a low expansion exponent compared to neat Polamid 66. It was detected that the use of an impact modifier led to less orientated fibers along the injection direction, which resulted in lower modulus and strength in terms of mechanical properties. Full article
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15 pages, 3693 KiB  
Article
Development and Characterization of New Energetic Composites Based on HNTO/AN Co-Crystal and Nitro-Cellulosic Materials
by Hani Boukeciat, Ahmed Fouzi Tarchoun, Djalal Trache, Amir Abdelaziz, Redha Meziani and Thomas M. Klapötke
Polymers 2023, 15(7), 1799; https://doi.org/10.3390/polym15071799 - 06 Apr 2023
Cited by 4 | Viewed by 1619
Abstract
To develop advanced cellulose-based energetic composites, new types of high-energy-density formulations containing hydrazine 3-nitro-1,2,4-triazol-5-one (HNTO)/ammonium nitrate (AN) cocrystals combined with nitrocellulose or nanostructured cellulose nitrate (NC and NMCC) were experimentally characterized. The prepared energetic formulations were analyzed in terms of their physicochemical properties, [...] Read more.
To develop advanced cellulose-based energetic composites, new types of high-energy-density formulations containing hydrazine 3-nitro-1,2,4-triazol-5-one (HNTO)/ammonium nitrate (AN) cocrystals combined with nitrocellulose or nanostructured cellulose nitrate (NC and NMCC) were experimentally characterized. The prepared energetic formulations were analyzed in terms of their physicochemical properties, mechanical sensitivities, structural features, and thermal behavior. Their heats of combustion and theoretical energetic performance were assessed as well. Experimental results exhibited the inherent characteristics of the designed NC@HNTO/AN and NMCC@HNTO/AN, including improved density, specific impulse, and impact sensitivity compared to their raw compounds. Besides that, thermo-kinetic findings revealed that the as-prepared insensitive and high-energy-density composites undergo two exothermic decomposition processes, and that NC@HNTO/AN has higher thermal activity. The present study demonstrated the outstanding characteristics of the new composites and could serve as a reference for developing more advanced cellulose-based energetic formulations. Full article
(This article belongs to the Special Issue Cellulose Based Composites)
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16 pages, 2113 KiB  
Article
Fabrication of Polymeric Hydrogels Containing Esomeprazole for Oral Delivery: In Vitro and In Vivo Pharmacokinetic Characterization
by Irshad Ullah, Ayesha Shuja Farooq, Iffat Naz, Waqar Ahmad, Hidayat Ullah, Shama Sehar and Asif Nawaz
Polymers 2023, 15(7), 1798; https://doi.org/10.3390/polym15071798 - 06 Apr 2023
Viewed by 1424
Abstract
Hydrogel is one of the most interesting and excellent candidates for oral drug delivery. The current study focuses on formulation development of hydrogels for controlled oral delivery of esomeprazole. The hydrogels were prepared by solution casting method by dissolving polymers in Polyvinyl alcohol [...] Read more.
Hydrogel is one of the most interesting and excellent candidates for oral drug delivery. The current study focuses on formulation development of hydrogels for controlled oral delivery of esomeprazole. The hydrogels were prepared by solution casting method by dissolving polymers in Polyvinyl alcohol (PVA) solution. Calcium alginate, Hydroxyl propyl methylcellulose (HPMC), acrylic acid and chondroitin sulfate were used in the preparation of hydrogels. Fourier transform infrared (FTIR) analysis showed no incompatibilities between drug and excipients used in the preparation of formulations. The hydrogels were characterized for size and surface morphology. Drug encapsulation efficiency was measured by Ultraviolet-visible (UV-VIS) spectroscopy. In vitro release studies were carried out using dissolution apparatus. The formulated hydrogels were then compared with the marketed product in vivo using rabbits. The result indicates that prepared hydrogels have a uniform size with a porous surface. The esomeprazole encapsulation efficiency of the prepared hydrogels was found to be 83.1 ± 2.16%. The esomeprazole-loaded hydrogel formulations showed optimum and Pharmacopeial acceptable range swelling behavior. The release of esomeprazole is controlled for 24 h (85.43 ± 0.32% in 24 h). The swelling and release of drug results make the prepared hydrogels a potential candidate for the controlled delivery of esomeprazole. The release of the drug from prepared hydrogel followed the super case transport-2 mechanism. The in vivo studies showed that prepared hydrogel formulations showed controlled and prolonged release of esomeprazole as compared to drug solution and marketed product. The formulations were kept for stability studies; there was no significant change observed in physical parameters, i.e., (appearance, color change and grittiness) at 40 °C ± 2/75% ± RH. There was a negligible difference in the drug content observed after the stability study suggested that all the formulations are stable under the given conditions for 60 days. The current study provides a valuable perspective on the controlled release profile of Hydroxyl propyl methylcellulose (HPMC) and calcium alginate-based esomeprazole hydrogels. Full article
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16 pages, 2312 KiB  
Article
Immobilization Approach as a Creative Strategy to Remove Reactive Dye Red 195 and Cu2+ Ions from Wastewater Using Environmentally Benign Geopolymer Cement
by Doaa A. Ahmed, Morsy A. El-Apasery and Shereen M. Ragai
Polymers 2023, 15(7), 1797; https://doi.org/10.3390/polym15071797 - 05 Apr 2023
Cited by 4 | Viewed by 1364
Abstract
Water is a resource that is essential to almost all phases of industrial and manufacturing operations globally. It is important to handle the wastewater generated professionally. The textile industry is one of the major global polluters, with textile producers responsible for one-fifth of [...] Read more.
Water is a resource that is essential to almost all phases of industrial and manufacturing operations globally. It is important to handle the wastewater generated professionally. The textile industry is one of the major global polluters, with textile producers responsible for one-fifth of all industrial water pollution worldwide. In contrast, heavy metal contamination has developed into a critical, expanding global environmental problem. Geopolymer is a cementitious constituent of amorphous aluminosilicates derived from natural or industrial wastes. It is produced using the polymerization of aluminosilicate raw ingredients in an alkaline atmosphere. The aim of this study is to evaluate the application of eco-friendly geopolymer cement in the immobilization technique for the treatment of wastewater including heavy metals and dyes. Geopolymer cement pastes were organized using slag and fly ash as an aluminosilicate source, (1:1) sodium silicate and sodium hydroxide 15 wt.% as an alkali activator in the presence of organic dye pollutant reactive red 195, and Cu2+ ions (700 ppm) at different hydration times for up to 28 days. The physicochemical and mechanical properties of the prepared geopolymer cement mixes were further examined in relation to reactive dye pollutant and Cu2+ ions. The hydration characteristic was examined using the compressive strength and % of total porosity tests, as well as FTIR and XRD studies. Our findings support the 100% immobilization of both Cu2+ ions and organic dye pollutants in prepared geopolymer pastes for up to 28 days of hydration. Additionally, adding both Cu2+ ions and dye pollutants to the prepared geopolymer paste improves its mechanical properties, which is also supported by FTIR data. XRD and FTIR studies showed that the Cu2+ ions and dying bath effluent addition have no influence on the kind of hydration products that are produced. On the other hand, the geopolymerization process is negatively impacted by the presence of Cu2+ ions alone in the geopolymer paste. Full article
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11 pages, 1516 KiB  
Article
Variation of the Tensile Properties of Basalt-Fiber-Reinforced Polybutylene Succinate Matrix Composites during Microbial Degradation
by Lovisa Rova, Hiroki Kurita, Shinji Kudo, Sho Hatayama, Teruyoshi Kanno, Alia Gallet--Pandellé and Fumio Narita
Polymers 2023, 15(7), 1796; https://doi.org/10.3390/polym15071796 - 05 Apr 2023
Cited by 2 | Viewed by 1551
Abstract
Little is known about how the strength of biodegradable polymers changes during decomposition. This study investigated the changes in the tensile properties of polybutylene succinate (PBS) and basalt-fiber (BF)-reinforced PBS (PBS-BF) composite sheets during degradation in bacterial solutions. Seven days after the start [...] Read more.
Little is known about how the strength of biodegradable polymers changes during decomposition. This study investigated the changes in the tensile properties of polybutylene succinate (PBS) and basalt-fiber (BF)-reinforced PBS (PBS-BF) composite sheets during degradation in bacterial solutions. Seven days after the start of the experiment, the elongation at break of the PBS specimens decreased significantly, and the PBS-BF composite specimens were characterized by barely any change in ultimate tensile strength (UTS) after immersion in the bacteria-free medium for 7 and 56 days. Meanwhile, when immersed in the bacterial solution, the UTS of the PBS-BF composite specimens showed a tendency to decrease after 7 days. After 56 days, the UTS decreased to about half of its value immediately after fabrication. The degradation of the material was attributed to infiltration of the bacterial solution into structurally weak areas, causing decomposition throughout the material. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Japan (2021,2022))
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14 pages, 4227 KiB  
Article
pH-Sensitive Degradable Oxalic Acid Crosslinked Hyperbranched Polyglycerol Hydrogel for Controlled Drug Release
by Bianca Andrade de Campos, Natalia Cristina Borges da Silva, Lucas Szmgel Moda, Pedro Vidinha and Lígia Passos Maia-Obi
Polymers 2023, 15(7), 1795; https://doi.org/10.3390/polym15071795 - 05 Apr 2023
Cited by 2 | Viewed by 1911
Abstract
pH-sensitive degradable hydrogels are smart materials that can cleave covalent bonds upon pH variation, leading to their degradation. Their development led to many applications for drug delivery, where drugs can be released in a pH-dependent manner. Crosslinking hyperbranched polyglycerol (HPG), a biocompatible building [...] Read more.
pH-sensitive degradable hydrogels are smart materials that can cleave covalent bonds upon pH variation, leading to their degradation. Their development led to many applications for drug delivery, where drugs can be released in a pH-dependent manner. Crosslinking hyperbranched polyglycerol (HPG), a biocompatible building block bearing high end-group functionality, using oxalic acid (OA), a diacid that can be synthesized from CO2 and form highly activated ester bonds, can generate this type of smart hydrogel. Aiming to understand the process of developing this novel material and its drug release for oral administration, its formation was studied by varying reactant stoichiometry, concentration and cure procedure and temperature; it was characterized regarding gel percent (%gel), swelling degree (%S), FTIR and thermal behavior; impregnated using ibuprofen, as a model drug, and a release study was carried out at pH 2 and 7. Hydrogel formation was evidenced by its insolubility, FTIR spectra and an increase in Td and Tg; a pre-cure step was shown to be crucial for its formation and an increase in the concentration of the reactants led to higher %gel and lower %S. The impregnation resulted in a matrix-encapsulated system; and the ibuprofen release was negligible at pH 2 but completed at pH 7 due to the hydrolysis of the matrix. A pH-sensitive degradable HPG-OA hydrogel was obtained and it can largely be beneficial in controlled drug release applications. Full article
(This article belongs to the Special Issue Biomedical Applications of Intelligent Hydrogel)
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22 pages, 9981 KiB  
Article
Aging of Wood for Musical Instruments: Analysis of Changes in Color, Surface Morphology, Chemical, and Physical-Acoustical Properties during UV and Thermal Exposure
by Lidia Gurău, Maria Cristina Timar, Camelia Coșereanu, Mihaela Cosnita and Mariana Domnica Stanciu
Polymers 2023, 15(7), 1794; https://doi.org/10.3390/polym15071794 - 05 Apr 2023
Cited by 3 | Viewed by 1558
Abstract
The acoustic features of old resonance wood in violins exhibit a superior quality when compared to those from new resonance wood. This study focuses on an assessment of the sound quality of two types of wood for musical instruments, spruce and maple (class [...] Read more.
The acoustic features of old resonance wood in violins exhibit a superior quality when compared to those from new resonance wood. This study focuses on an assessment of the sound quality of two types of wood for musical instruments, spruce and maple (class A and D), before and after aging via thermal and UV exposure. The samples were characterized before and after UV aging in terms of color change (using a Chroma meter), surface morphology (using a MarSurf XT20 instrument), chemical changes (monitored by FTIR spectroscopy), and sound propagation speed (using an ultrasound device). After UV treatment, the wavier surface increased the area of exposure and degradation. Also, the color changes were found to be more accentuated in the case of spruce compared to sycamore maple. The FTIR results indicated more advanced aging processes for spruce when compared to maple under the same experimental conditions. This difference resulted mostly from the increased formation of carbonyl-containing chromophores via oxidative processes in spruce rather than in maple, which is in agreement with the color change findings. Exposure of both species to thermal and UV radiation led to an increase in sound propagation speed, both longitudinally and radially, and to a greater extent in wood quality class A when compared to quality class D. Full article
(This article belongs to the Special Issue Durability and Modification of Wood Surfaces II)
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15 pages, 12467 KiB  
Article
Eudragit Films as Carriers of Lipoic Acid for Transcorneal Permeability
by Karina L. Bierbrauer, Laura R. Comini, Victoria Leonhard, Micaela A. Escobar Manzanelli, Gabriela Castelli, Silvia Farfán, Roxana V. Alasino and Dante M. Beltramo
Polymers 2023, 15(7), 1793; https://doi.org/10.3390/polym15071793 - 05 Apr 2023
Cited by 2 | Viewed by 1299
Abstract
Diabetes mellitus (DM) is a highly prevalent disease affecting almost 10% of the world population; it is characterized by acute and chronic conditions. Diabetic patients have twenty-five times higher risk of going blind and developing cataracts early than the general population. Alpha-lipoic acid [...] Read more.
Diabetes mellitus (DM) is a highly prevalent disease affecting almost 10% of the world population; it is characterized by acute and chronic conditions. Diabetic patients have twenty-five times higher risk of going blind and developing cataracts early than the general population. Alpha-lipoic acid (LA) is a highly valuable natural antioxidant for the prevention and treatment of ophthalmic complications, such as diabetic keratopathy and retinopathy. However, its applicability is limited due to its low solubility in water; therefore, suitable systems are required for its formulation. In this work we developed an erodible insert based on Eudragit E100 (E PO) and Lipoic Acid (LA) for the delivery of this compound for the preventive treatment of ocular diseases especially in diabetic patients. Film evaluation was carried out by mechanical and thermal properties, mucoadhesivity, drug release, dynamic light scattering and corneal permeability as the concentration of LA increased. It was shown that upon LA release, it forms nanoparticles in combination with E PO that favor corneal permeation and LA retention in the cornea. These E PO-LA films also resulted non-irritable hence they are promising for their application in the treatment of ocular diseases. Full article
(This article belongs to the Special Issue Polymer Materials for Drug Delivery and Tissue Engineering II)
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23 pages, 13917 KiB  
Article
Deformation Behavior Investigation of Auxetic Structure Made of Poly(butylene adipate-co-terephthalate) Biopolymers Using Finite Element Method
by Yanling Schneider, Vinzenz Guski, Siegfried Schmauder, Javad Kadkhodapour, Jonas Hufert, Axel Grebhardt and Christian Bonten
Polymers 2023, 15(7), 1792; https://doi.org/10.3390/polym15071792 - 04 Apr 2023
Cited by 1 | Viewed by 1752
Abstract
Auxetic structures made of biodegradable polymers are favorable for industrial and daily life applications. In this work, poly(butylene adipate-co-terephthalate) (PBAT) is chosen for the study of the deformation behavior of an inverse-honeycomb auxetic structure manufactured using the fused filament fabrication. The study focus [...] Read more.
Auxetic structures made of biodegradable polymers are favorable for industrial and daily life applications. In this work, poly(butylene adipate-co-terephthalate) (PBAT) is chosen for the study of the deformation behavior of an inverse-honeycomb auxetic structure manufactured using the fused filament fabrication. The study focus is on auxetic behavior. One characteristic of polymer deformation prediction using finite element (FE) simulation is that no sounded FE model exists, due to the significantly different behavior of polymers under loading. The deformation behavior prediction of auxetic structures made of polymers poses more challenges, due to the coupled influences of material and topology on the overall behavior. Our work presents a general process to simulate auxetic structural deformation behavior for various polymers, such as PBAT, PLA (polylactic acid), and their blends. The current report emphasizes the first one. Limited by the state of the art, there is no unified regulation for calculating the Poisson’s ratio ν for auxetic structures. Here, three calculation ways of ν are presented based on measured data, one of which is found to be suitable to present the auxetic structural behavior. Still, the influence of the auxetic structural topology on the calculated Poisson’s ratio value is also discussed, and a suggestion is presented. The numerically predicted force–displacement curve, Poisson’s ratio evolution, and the deformed auxetic structural status match the testing results very well. Furthermore, FE simulation results can easily illustrate the stress distribution both statistically and local-topology particularized, which is very helpful in analyzing in-depth the auxetic behavior. Full article
(This article belongs to the Special Issue Polymeric Metamaterials: Design, Fabrication, Testing and Modeling)
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20 pages, 1319 KiB  
Article
Molecular Weight Distribution of Branched Polymers: Comparison between Monte Carlo Simulation and Flory-Stockmayer Theory
by Chengyuan Wen, Roy Odle and Shengfeng Cheng
Polymers 2023, 15(7), 1791; https://doi.org/10.3390/polym15071791 - 04 Apr 2023
Cited by 4 | Viewed by 1602
Abstract
It is challenging to predict the molecular weight distribution (MWD) for a polymer with a branched architecture, though such information will significantly benefit the design and development of branched polymers with desired properties and functions. A Monte Carlo (MC) simulation method based on [...] Read more.
It is challenging to predict the molecular weight distribution (MWD) for a polymer with a branched architecture, though such information will significantly benefit the design and development of branched polymers with desired properties and functions. A Monte Carlo (MC) simulation method based on the Gillespie algorithm is developed to quickly compute the MWD of branched polymers formed through step-growth polymerization, with a branched polyetherimide from two backbone monomers (4,4-bisphenol A dianhydride and m-phenylenediamine), a chain terminator (phthalic anhydride), and a branching agent (tris[4-(4-aminophenoxy)phenyl] ethane) as an example. This polymerization involves four reactions that can be all reduced to a condensation reaction between an amine group and a carboxylic anhydride group. A comparison between the MC simulation results and the predictions of the Flory-Stockmayer theory on MWD shows that the rates of the reactions are determined by the concentrations of the functional groups on the monomers involved in each reaction. It further shows that the Flory-Stockmayer theory predicts MWD well for systems below the gel point but starts to fail for systems around or above the gel point. However, for all the systems, the MC method can be used to reliably predict MWD no matter if they are below or above the gel point. Even for a macroscopic system, a converging distribution can be quickly obtained through MC simulations on a system of only a few hundred to a few thousand monomers that have the same molar ratios as in the macroscopic system. Full article
(This article belongs to the Special Issue Research on Polymer Simulation, Modeling and Computation)
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15 pages, 3609 KiB  
Article
“Green” PBX Formulations Based on High Explosives (RDX and HMX) and Water-Soluble pH-Sensitive Polymeric Binders
by Traian Rotariu, Andreea Elena Moldovan, Gabriela Toader, Aurel Diacon, Edina Rusen, Raluca Elena Ginghina, Ovidiu Iorga, Horia Răzvan Botiș and Thomas Klapötke
Polymers 2023, 15(7), 1790; https://doi.org/10.3390/polym15071790 - 04 Apr 2023
Viewed by 2678
Abstract
The increasingly harsher and more complex international and European environmental legislation drives the current development of “greener” energetics materials and munitions. The aerospace and defense industries rely on extensive research in the formulation and scale-up production of polymer-bonded explosives (PBX). In this context, [...] Read more.
The increasingly harsher and more complex international and European environmental legislation drives the current development of “greener” energetics materials and munitions. The aerospace and defense industries rely on extensive research in the formulation and scale-up production of polymer-bonded explosives (PBX). In this context, this paper aims to present a versatile method for obtaining “green” PBX formulations based on two high explosives (hexogen (RDX) and octogen (HMX)) and acrylic acid—ethyl acrylate copolymeric binders. This study developed an innovative “eco-friendly” technology for coating the RDX and HMX crystals, allowing straightforward and safer manufacture of PBX, avoiding the use of traditional organic solvents. At the same time, these polymeric binders are soluble in water at a slightly alkaline pH and insoluble at acidic or neutral pH, thus ensuring a safer manipulation of the energetic materials during their entire life cycle and a facile recovery of the explosive in its original shape and morphology in demilitarization. The PBX formulations were characterized via specific analytical tools to evaluate the influence of their composition on the safety and performance characteristics: scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), alkaline pH solubility tests, differential thermal analysis (DTA), impact sensitivity test (BAM Fall Hammer Test), friction sensitivity test (BAM Friction Test), electrostatic sensitivity test (ESD), vacuum stability test, small scale shock reactivity test (SSRT), detonation velocity test. The “green” PBX formulations obtained through a simple and innovative coating method, based on the polymeric binders’ adjustable water solubility, demonstrated remarkable energetic performances and a facile recovery of the explosive crystals by the dissolution of the polymeric binder at pH 11 and 30 °C. Full article
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23 pages, 4572 KiB  
Review
Polysaccharides Are Effective Inhibitors of Natural Gas Hydrate Formation
by Alsu Venerovna Fakhreeva, Vasily Viktorovich Nosov, Alexander Iosifovich Voloshin and Vladimir Anatolyevich Dokichev
Polymers 2023, 15(7), 1789; https://doi.org/10.3390/polym15071789 - 04 Apr 2023
Cited by 3 | Viewed by 1997
Abstract
This review covers the types and applications of chemical inhibitors of gas hydrate formation in the oil and gas industry. The main directions of the development of new types of highly effective and environmentally safe “green” kinetic hydrate inhibitors (KHIs) based on biopolymers [...] Read more.
This review covers the types and applications of chemical inhibitors of gas hydrate formation in the oil and gas industry. The main directions of the development of new types of highly effective and environmentally safe “green” kinetic hydrate inhibitors (KHIs) based on biopolymers are analyzed. The structure, physicochemical properties, efficiency of gas hydrate formation inhibition, and commercial prospects of polysaccharides in preventing and controlling the formation of gas hydrates are considered. The criteria for their selection, current experimental data, and the mechanism of inhibition are presented. Recent research in the development of cost-effective, efficient, and biodegradable KHIs for industrial applications in the oil and gas industry is also presented. Full article
(This article belongs to the Special Issue Eco-Friendly Supramolecular Polymeric Materials)
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15 pages, 3109 KiB  
Article
Study of the Plasticization Effect of 1-Ethyl-3-methylimidazolium Acetate in TPS/PVA Biodegradable Blends Produced by Melt-Mixing
by Jennifer M. Castro, Mercedes G. Montalbán, Daniel Domene-López, Ignacio Martín-Gullón and Juan C. García-Quesada
Polymers 2023, 15(7), 1788; https://doi.org/10.3390/polym15071788 - 04 Apr 2023
Cited by 1 | Viewed by 1914
Abstract
The first step towards the production and marketing of bioplastics based on renewable and sustainable materials is to know their behavior at a semi-industrial scale. For this reason, in this work, the properties of thermoplastic starch (TPS)/polyvinyl alcohol (PVA) films plasticized by a [...] Read more.
The first step towards the production and marketing of bioplastics based on renewable and sustainable materials is to know their behavior at a semi-industrial scale. For this reason, in this work, the properties of thermoplastic starch (TPS)/polyvinyl alcohol (PVA) films plasticized by a green solvent, as the 1-ethyl-3-methylimidazolium acetate ([Emim+][Ac]) ionic liquid, produced by melt-mixing were studied. These blends were prepared with a different content of [Emim+][Ac] (27.5–42.5 %wt.) as a unique plasticizer. According to the results, this ionic liquid is an excellent plasticizer due to the transformation of the crystalline structure of the starch to an amorphous state, the increase in flexibility, and the drop in Tg, as the [Emim+][Ac] amount increases. These findings show that the properties of these biomaterials could be modified in the function of [Emim+][Ac] content in the formulations of TPS, depending on their final use, thus becoming a functional alternative to conventional polymers. Full article
(This article belongs to the Special Issue Natural-Based Biodegradable Polymeric Materials)
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16 pages, 8742 KiB  
Article
Pressure Drop Dynamics during Filtration of Mixture Aerosol Containing Water, Oil, and Soot Particles on Nonwoven Filters
by Mateusz Kamiński, Jakub M. Gac, Piotr Sobiech, Paweł Kozikowski and Tomasz Jankowski
Polymers 2023, 15(7), 1787; https://doi.org/10.3390/polym15071787 - 04 Apr 2023
Viewed by 2202
Abstract
The pressure drop dynamics during the filtration of three-component mixture aerosols are investigated and compared with two and single-component aerosols. The main area of interest is the effect of the addition of a small quantity of liquid (oil) and solid (soot) particles during [...] Read more.
The pressure drop dynamics during the filtration of three-component mixture aerosols are investigated and compared with two and single-component aerosols. The main area of interest is the effect of the addition of a small quantity of liquid (oil) and solid (soot) particles during the filtration of aerosol containing water mist. In addition, calculations of the change in filter mass during oil aerosol filtration have been carried out and compared with the experimental results. The new, improved filtration efficiency model takes into account a better coefficient fitting in the filtration mechanism equations. The limitations in the change in fibre diameter and packing density resulting from the filter loading have been implemented in the model. Additionally, the calculation model employs the fibre size distribution representation via multiple average fibre diameters. The changes in fibre diameter are dependent on each fibre’s calculated filtration efficiency. The improved filtration model has been utilised to predict the mass change of the filters during the filtration of pure and mixture aerosols. The pressure drop calculation model based on changes in filter mass has been formulated. The model is then utilised to calculate pressure drop changes resulting from the filtration of the oil aerosol and water and oil mixture aerosol. Full article
(This article belongs to the Section Polymer Fibers)
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20 pages, 3484 KiB  
Article
In Vitro Effects of Waterborne Polyurethane 3D Scaffolds Containing Poly(lactic-co-glycolic acid)s of Different Lactic Acid/Glycolic Acid Ratios on the Inflammatory Response
by Guanyu Zhang, Ao Zhen, Jinlin Chen, Bohong Du, Feng Luo, Jiehua Li and Hong Tan
Polymers 2023, 15(7), 1786; https://doi.org/10.3390/polym15071786 - 04 Apr 2023
Cited by 1 | Viewed by 1337
Abstract
The physical and chemical properties of tissue engineering scaffolds have considerable effects on the inflammatory response at the implant site in soft tissue repair. The development of inflammation-modulating polymer scaffolds for soft tissue repair is attracting increasing attention. In this study, in order [...] Read more.
The physical and chemical properties of tissue engineering scaffolds have considerable effects on the inflammatory response at the implant site in soft tissue repair. The development of inflammation-modulating polymer scaffolds for soft tissue repair is attracting increasing attention. In this study, in order to regulate the inflammatory response at the implant site, a series of waterborne polyurethane (WPU) scaffolds with different properties were synthesized using polyethylene glycol (PEG), polycaprolactone (PCL) and poly (lactic acid)–glycolic acid copolymers (PLGAs) with three lactic acid/glycolic acid (LA/GA) ratios as the soft segments. Then, scaffolds were obtained using freeze-drying. The WPU scaffolds exhibited a porous cellular structure, high porosity, proper mechanical properties for repairing nerve tissue and an adjustable degradation rate. In vitro cellular experiments showed that the degradation solution possessed high biocompatibility. The in vitro inflammatory response of C57BL/6 mouse brain microglia (immortalized) (BV2) cells demonstrated that the LA/GA ratio of the PLGA in WPU scaffolds can regulate the external inflammatory response by altering the secretion of IL-10 and TNF-α. Even the IL-10/TNF-α of PU5050 (3.64) reached 69 times that of the control group (0.053). The results of the PC12 culture on the scaffolds showed that the scaffolds had positive effects on the growth, proliferation and differentiation of nerve cells and could even promote the formation of synapses. Overall, these scaffolds, particularly the PU5050, indeed prevent BV2 cells from differentiating into a pro-inflammatory M1 phenotype, which makes them promising candidates for reducing the inflammatory response and repairing nerve tissue. Furthermore, PU5050 had the best effect on preventing the transformation of BV2 cells into the pro-inflammatory M1 phenotype. Full article
(This article belongs to the Special Issue Polymeric Structures for Biomedical Use)
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15 pages, 2658 KiB  
Article
Bio-Based Polyurethane Foams for the Removal of Petroleum-Derived Pollutants: Sorption in Batch and in Continuous-Flow
by Fabrizio Olivito, Vincenzo Algieri, Antonio Jiritano, Matteo Antonio Tallarida, Paola Costanzo, Loredana Maiuolo and Antonio De Nino
Polymers 2023, 15(7), 1785; https://doi.org/10.3390/polym15071785 - 03 Apr 2023
Cited by 7 | Viewed by 1910
Abstract
In this paper, we evaluated the potential of two synthesized bio-based polyurethane foams, PU1 and PU2, for the removal of diesel and gasoline from water mixtures. We started the investigation with the experiment in batch. The total sorption capacity S (g/g) for the [...] Read more.
In this paper, we evaluated the potential of two synthesized bio-based polyurethane foams, PU1 and PU2, for the removal of diesel and gasoline from water mixtures. We started the investigation with the experiment in batch. The total sorption capacity S (g/g) for the diesel/water system was slightly higher with respect to gasoline/water, with a value of 62 g/g for PU1 and 65 g/g for PU2. We found that the sorption follows a pseudo second-order kinetic model for both the materials. The experimental data showed that the best isotherm models were obtained with Langmuir and Redlich–Peterson models. In addition, to provide an idea of the process scalability for future industrial applications, we tested the sorption capacity of the foams using a continuous-flow of the same oil/water mixtures and we obtained performances even better with respect to the batch test. The regeneration can be performed up to 50 times by centrifuge, without losing efficacy. Full article
(This article belongs to the Special Issue Biopolymers: Structure-Function Relationship and Application II)
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18 pages, 8700 KiB  
Article
Accelerated Aging on the Compression Properties of a Green Polyurethane Foam: Experimental and Numerical Analysis
by Enio H. P. Da Silva, Silvio De Barros, André F. C. Vieira, Romeu R. C. Da Costa and Marcelo L. Ribeiro
Polymers 2023, 15(7), 1784; https://doi.org/10.3390/polym15071784 - 03 Apr 2023
Cited by 4 | Viewed by 2208
Abstract
The aim of this work is to evaluate the changes in compression properties of a bio-based polyurethane foam after exposure to 90 °C for different periods of time, and to propose a method to extrapolate these results and use a numerical approach to [...] Read more.
The aim of this work is to evaluate the changes in compression properties of a bio-based polyurethane foam after exposure to 90 °C for different periods of time, and to propose a method to extrapolate these results and use a numerical approach to predict the compression behaviour after degradation for untested conditions at different degradation times and temperatures. Bio-based polymers are an important sustainable alternative to oil-based materials. This is explained by the foaming process and the density along the material as it was possible to see in a digital image correlation analysis. After 60 days, stiffness was approximately decreased by half in both directions. The decrease in yield stress due to thermo-oxidative degradation had a minor effect in the foaming directions, changing from 352 kPa to 220 kPa after 60 days, and the transverse property was harshly impacted changing from 530 kPa to 265 kPa. The energy absorption efficiency was slightly affected by degradation. The simulation of the compression stress-strain curves were in accordance to the experimental data and made it possible to predict the changes in mechanical properties for intermediate periods of degradation time. The plateau stress for the unaged foam transverse to the foaming direction presented experimental and numerical values of 450 kPa and 470 kPa, respectively. In addition, the plateau stresses in specimens degraded for 40 days present very similar experimental and numerical results in the same direction, at 310 kPa and 300 kPa, respectively. Therefore, this paper presents important information regarding the life-span and degradation of a green PUF. It provides insights into how compression properties vary along degradation time as function of material operation temperature, according to the Arrhenius degradation equation. Full article
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15 pages, 3191 KiB  
Article
Formation of pH-Responsive Cotton by the Adsorption of Methyl Orange Dye
by Mateja Kert and Jasna Skoko
Polymers 2023, 15(7), 1783; https://doi.org/10.3390/polym15071783 - 03 Apr 2023
Cited by 1 | Viewed by 1937
Abstract
The interest in pH-sensitive textile sensors is growing in the global market. Due to their low-cost production, mechanical stability, flexibility, air-permeability, washability, and reusability, they are more suitable than electronic sensor systems. The research tailored the pH-sensitive textile by applying the pH indicator [...] Read more.
The interest in pH-sensitive textile sensors is growing in the global market. Due to their low-cost production, mechanical stability, flexibility, air-permeability, washability, and reusability, they are more suitable than electronic sensor systems. The research tailored the pH-sensitive textile by applying the pH indicator methyl orange to the cotton fabric during conventional dyeing. Adsorption of methyl orange dye to cotton fabric is hindered due to electrostatic repulsive forces between dye anions and negatively charged cotton fibre. To overcome this problem, chemical modification of cotton fabric using a commercial product was performed. The pH sensitivity of the dyed fabric was spectrophotometrically evaluated. In addition, the colour fastness of dyed cotton fabric to washing, light, hot pressing and rubbing was investigated according to valid SIST EN ISO standards. The research results show that the pH-responsive cotton fabric was successfully developed. The chemical modification of cotton fabric is crucial for the increased adsorption of methyl orange dye. The halochromic effect was not only perceived spectrophotometrically but also with the naked eye. The developed halochromic cotton fabric showed poor colour fastness to light and good colour fastness to hot pressing and rubbing, while no significant improvement in colour fastness to washing was observed, even though the fabric was after-treated with a cationic fixing agent. Higher adsorption of the methyl orange dye to the cotton fabric during the dyeing process leads to less wastewater pollution after dyeing with unfixed dye and, thus, a reduction in wastewater treatment costs. Full article
(This article belongs to the Special Issue Stimuli-Responsive Polymers)
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10 pages, 1790 KiB  
Article
The Formation of Volume Transmission Gratings in Acrylamide-Based Photopolymers Using Curcumin as a Long-Wavelength Photosensitizer
by Katherine Pacheco, Gabriela Aldea-Nunzi, Agnieszka Pawlicka and Jean-Michel Nunzi
Polymers 2023, 15(7), 1782; https://doi.org/10.3390/polym15071782 - 03 Apr 2023
Cited by 1 | Viewed by 1164
Abstract
Curcumin, a natural dye found in the Curcuma longa rhizome, commonly called turmeric, is used as a photosensitizer in acrylamide-based photopolymers for holographic data storage. We studied the absorbance of photopolymer films that show two absorption bands due to curcumin, acrylamide monomer (AA), [...] Read more.
Curcumin, a natural dye found in the Curcuma longa rhizome, commonly called turmeric, is used as a photosensitizer in acrylamide-based photopolymers for holographic data storage. We studied the absorbance of photopolymer films that show two absorption bands due to curcumin, acrylamide monomer (AA), and the crosslinking agent N,N′-methylenebisacrylamide (MBA). Analysis of the real-time diffraction efficiency of these films shows a maximum of 16% for the sample with the highest curcumin concentration. Moreover, increasing the curcumin load enhanced the refractive index contrast from 7.8 × 10−4 for the photopolymer with the lowest curcumin load to 1.1 × 10−3 for the photopolymer with the largest load. The sensitivity and diffraction efficiency of the recorded gratings also increased from 7.0 to 9.8 cm·J−1 and from 7.9 to 16% with the increase in curcumin load, respectively. Finally, the influence of NaOH on the photopolymerization of the AA-curcumin-based sample shows a diffraction efficiency increase with the NaOH content, revealing that the curcumin enol form is more efficient as a photosensitizer. Full article
(This article belongs to the Collection Polymers for Electrical and Optical Applications)
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12 pages, 4771 KiB  
Article
Covalent Triazine Frameworks Decorated with Pyridine-Type Carbonitride Moieties: Enhanced Photocatalytic Hydrogen Evolution by Improved Charge Separation
by Xianxian Kong, Fan Yang, Xiaoying Li, Mengying Fu, Tao Zeng, Shuang Song, Zhiqiao He and Yan Yu
Polymers 2023, 15(7), 1781; https://doi.org/10.3390/polym15071781 - 03 Apr 2023
Cited by 1 | Viewed by 1151
Abstract
A simple procedure of calcination under an Ar atmosphere has been successfully applied to create a covalent triazine framework bearing pyridine-type carbonitride moieties (PCN@CTF). The appending of PCN on the CTF led to visible light absorption at up to 600 nm in the [...] Read more.
A simple procedure of calcination under an Ar atmosphere has been successfully applied to create a covalent triazine framework bearing pyridine-type carbonitride moieties (PCN@CTF). The appending of PCN on the CTF led to visible light absorption at up to 600 nm in the UV/Vis diffuse-reflectance spectra. Photoluminescence and electrochemical impedance spectroscopy have been applied to clarify how modification of the CTF with PCN enhanced the separation efficiency of photoexcited charge carriers. An optimized 1%PCN@CTF sample showed the highest photocatalytic hydrogen evolution reaction (HER) rate of 170.2 ± 2.3 μmol g−1·h−1, 3.9 times faster than that over the pristine CTF. The apparent quantum efficiency of the HER peaked at (7.57 ± 0.10)% at 490 nm. This representative 1% PCN@CTF sample maintained continuous function for at least 15 h. This work provides new guidance for modification with PCN materials as a means of obtaining high photocatalytic efficiency and sheds light on the effect of appended pyridine rings on a CTF. Full article
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13 pages, 5520 KiB  
Article
Multiscale Analysis of the Highly Stretchable Carbon−Based Polymer Strain Sensor
by Junpu Wang, Zhu Wang, Yanjiang Zuo and Wenzhi Wang
Polymers 2023, 15(7), 1780; https://doi.org/10.3390/polym15071780 - 03 Apr 2023
Cited by 1 | Viewed by 1160
Abstract
In this paper, a multiscale analysis method was proposed to simulate carbon nanoparticles (CNPs)−filled polymers which can be strain sensors applied in wearable electronic devices, flexible skin, and health monitoring fields. On the basis of the microstructure characteristics of the composite, a microscale [...] Read more.
In this paper, a multiscale analysis method was proposed to simulate carbon nanoparticles (CNPs)−filled polymers which can be strain sensors applied in wearable electronic devices, flexible skin, and health monitoring fields. On the basis of the microstructure characteristics of the composite, a microscale representative volume element model of the CNPs−filled polymer was established using the improved nearest−neighbor algorithm. By finite element analysis, the variation of the junction widths of adjacent aggregates can be extracted from the simulation results. Then, according to the conductive mechanism of CNP−filled polymers, the composite was simplified as a circuit network composed of vast random resistors which were determined by the junction widths between adjacent aggregates. Hence, by taking junction widths as the link, the resistance variation of the CNPs−filled polymer with the strain can be obtained. To verify the proposed method, the electromechanical responses of silicone elastomer filled with different CNPs under different filling amounts were investigated numerically and experimentally, respectively, and the results were in good agreement. Therefore, the multiscale analysis method can not only reveal the strain−sensing mechanism of the composite from the microscale, but also effectively predict the electromechanical behavior of the CNPs−filled polymer with different material parameters. Full article
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