Research

Jump to: Review

Open AccessArticle

Crystal-by-Crystal Assembly in Two Types of Periodically Banded Aggregates of Poly(p-Dioxanone)

by

,

,

and

Polymers 2023, 15(2), 393; https://doi.org/10.3390/polym15020393 - 11 Jan 2023

Viewed by 759

Abstract

The exterior and interior lamellar assemblies of poly(p-dioxanone) (PPDO) crystallized at 76 °C yield the most regular ones to interpret the 3D assembly mechanisms and potential for structural coloration iridescence, which are investigated using atomic-force microscopy (AFM), and scanning electron microscopy (SEM). PPDO [...] Read more.

The exterior and interior lamellar assemblies of poly(p-dioxanone) (PPDO) crystallized at 76 °C yield the most regular ones to interpret the 3D assembly mechanisms and potential for structural coloration iridescence, which are investigated using atomic-force microscopy (AFM), and scanning electron microscopy (SEM). PPDO displays two types of ring-banded spherulites within a range of T_c with dual-type birefringent spherulites (positive and negative-type) only within a narrow range of T_cs = 70–78 °C. At T_c > 80 °C, the inter-band spacing decreases from a maximum and the crystal assembly becomes irregularly corrupted and loses the capacity for light interference. Periodic grating assemblies are probed by in-depth 3D dissection into periodically banded crystal aggregates of poly(p-dioxanone) (PPDO) to disclose such layered gratings possessing iridescence features similar to nature’s structural coloration. This work amply demonstrates that grating assembly by orderly stacked crystal layers is feasible not only for accounting for the periodic birefringent ring bands with polarized light but also the distinct iridescence by interfering with white light. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Graphical abstract

Open AccessArticle

Self-Attractive Semiflexible Polymers under an External Force Field

by

Antonio Lamura

Polymers 2022, 14(21), 4762; https://doi.org/10.3390/polym14214762 - 07 Nov 2022

Viewed by 917

Abstract

The dynamical response of a tethered semiflexible polymer with self-attractive interactions and subjected to an external force field is numerically investigated by varying stiffness and self-interaction strength. The chain is confined in two spatial dimensions and placed in contact with a heat bath [...] Read more.

The dynamical response of a tethered semiflexible polymer with self-attractive interactions and subjected to an external force field is numerically investigated by varying stiffness and self-interaction strength. The chain is confined in two spatial dimensions and placed in contact with a heat bath described by the Brownian multi-particle collision method. For strong self-attraction the equilibrium conformations range from compact structures to double-stranded chains, and to rods when increasing the stiffness. Under the external field at small rigidities, the initial close-packed chain is continuously unwound by the force before being completely elongated. For double-stranded conformations the transition from the folded state to the open one is sharp being steeper for larger stiffnesses. The discontinuity in the transition appears in the force-extension relation, as well as in the probability distribution function of the gyration radius. The relative deformation with respect to the equilibrium case along the direction normal to the force is found to decay as the inverse of the applied force. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Figure 1

Open AccessArticle

Aero Grade Epoxy Vitrimer towards Commercialization

by

Alaitz Ruiz de Luzuriaga

,

,

,

,

and

Polymers 2022, 14(15), 3180; https://doi.org/10.3390/polym14153180 - 04 Aug 2022

Cited by 6 | Viewed by 2832

Abstract

Traditional crosslinked aero grade epoxy resins have excellent thermal-mechanical properties and solvent resistance, but they cannot be remolded, recycled, or repaired. Vitrimers can be topologically rearranged via an associative exchange mechanism, endowing them with thermoplasticity. Introducing dynamic bonds into crosslinked networks to obtain [...] Read more.

Traditional crosslinked aero grade epoxy resins have excellent thermal-mechanical properties and solvent resistance, but they cannot be remolded, recycled, or repaired. Vitrimers can be topologically rearranged via an associative exchange mechanism, endowing them with thermoplasticity. Introducing dynamic bonds into crosslinked networks to obtain more sustainable thermosets is currently an interesting research topic. While recent research into vitrimers has indicated many advantages over traditional thermosets, an important shortcoming has been identified: susceptibility to creep at service temperature due to the dynamic bonds present in the network. In addition, designing aero grade epoxy vitrimers (similar to RTM6 resin) still remains a challenge. Herein, low creep aero grade epoxy vitrimer with thermal and mechanical properties similar to those of aero grade epoxy resins and with the ability to be recyclable, repairable, and reprocessable, has been prepared. In this manuscript, we demonstrate that aero grade epoxy vitrimer with reduced creep can be easily designed by the introduction of a certain fraction of permanent crosslinks, without having a negative effect on the stress relaxation of the material. Subsequently, the mechanical and relaxation properties were investigated and compared with those of classical aero grade epoxy resin. A high Tg (175 °C) epoxy vitrimer was obtained which fulfilled all mechanical and thermal specifications of the aero sector. This work provides a simple network design to obtain aero grade epoxy resins with excellent creep resistance at elevated temperatures while being sustainable. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Graphical abstract

Open AccessArticle

Cross-Linking of Polypropylene with Thiophene and Imidazole

by

,

,

,

and

Polymers 2022, 14(11), 2198; https://doi.org/10.3390/polym14112198 - 28 May 2022

Viewed by 1434

Abstract

In this work, two novel routes to synthesis cross-linked polypropylene (PP) are introduced by using two different precursors (2-thiophenemethyl amine (TMA) and 1-(3 aminopropyl) imidazole (API)), both cross-linked with 1,1′-(methylenedi-4,1-phenylene) bismaleimide (BM) at two different annealing temperature values (T = 50 °C [...] Read more.

In this work, two novel routes to synthesis cross-linked polypropylene (PP) are introduced by using two different precursors (2-thiophenemethyl amine (TMA) and 1-(3 aminopropyl) imidazole (API)), both cross-linked with 1,1′-(methylenedi-4,1-phenylene) bismaleimide (BM) at two different annealing temperature values (T = 50 °C and T = 150 °C). Both Diels–Alder (DA) and Michael addition reactions were successfully performed with TMA and API, respectively, albeit with different reactivity. Imidazole clearly shows a higher reactivity compared to thiophene. In addition, an increase in annealing temperature leads to a higher degree of cross-linking. The highest degree of cross-linking was obtained by the imidazole product after annealing at 150 °C (IMG1A150) as evident from the highest complex viscosity (|η*|) value of IMG1A150. A difference in rheology and thermal properties between the imidazole and thiophene cross-linked products was also observed. However, both products have superior melt properties and thermal stability compared with the starting material. They show processability at high temperatures. The melt flow behavior and de-cross-linking at higher temperatures can be tuned depending on the choice of imidazole or thiophene. This study shows an advance on the cross-linked PP processing and its product performances for further application on the commercial scale. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Figure 1

Open AccessArticle

The Influence of Oxidant on Gelatin–Tannin Hydrogel Properties and Structure for Potential Biomedical Application

by

Konstantin Osetrov

,

Mayya Uspenskaya

and

Vera Sitnikova

Polymers 2022, 14(1), 150; https://doi.org/10.3390/polym14010150 - 31 Dec 2021

Cited by 5 | Viewed by 1573

Abstract

Nowadays, there is a widespread usage of sodium periodate as an oxidant for synthesizing gelatin–tannin hydrogels. The impact of iodine compounds could have a harmful effect on human health. The study focuses on the proposal of alternative oxidizing systems for tannin oxidation. Gelatin–tannin [...] Read more.

Nowadays, there is a widespread usage of sodium periodate as an oxidant for synthesizing gelatin–tannin hydrogels. The impact of iodine compounds could have a harmful effect on human health. The study focuses on the proposal of alternative oxidizing systems for tannin oxidation. Gelatin–tannin hydrogels were obtained based on the usage of H₂O₂/DMSO/KMnO₄/KIO₄ oxidants and characterized with sorption, thermal (TGA, DTG, DSC), mechanical, FTIR and other methods. The sorption experiments were carried out in a phosphate buffer (pH = 5.8/7.4/9) and distilled water and were investigated with Fick’s law and pseudosecond order equation. The pH dependence of materials in acid media indicates the possibility of further usage as stimuli-responsive systems for drug delivery. Thermal transitions demonstrate the variation of structure with melting (306 ÷ 319 °C) and glass transition temperatures (261 ÷ 301 °C). The activation energy of water evaporation was calculated by isoconversional methods (Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa) ranging from 4 ÷ 18 to 14 ÷ 38 kJ/mole and model-fitting (Coats–Redfern, Kennedy–Clark) methods at 24.7 ÷ 45.3 kJ/mole, indicating the smooth growth of values with extent of conversion. The network parameters of the hydrogels were established by modified Flory–Rehner and rubber elasticity theories, which demonstrated differences in values (5.96 ÷ 21.27·10⁻³ mol/cm³), suggesting the limitations of theories. The sorption capacity, tensile strength and permeability for water/oxygen indicate that these materials may find their application in field of biomaterials. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Figure 1

Open AccessArticle

Preparation and Characterization of Self-Healing Polyurethane Powder Coating Using Diels–Alder Reaction

by

Negin Farshchi

,

Michaela Gedan-Smolka

and

Markus Stommel

Polymers 2021, 13(21), 3803; https://doi.org/10.3390/polym13213803 - 03 Nov 2021

Cited by 4 | Viewed by 1765

Abstract

Although powder coating systems offer many environmental, ecological and energy related benefits over liquid based coatings, in the case of uretdione based polyurethane systems, high curing temperature is still an issue. On the other hand, powder coating systems make it possible to reduce [...] Read more.

Although powder coating systems offer many environmental, ecological and energy related benefits over liquid based coatings, in the case of uretdione based polyurethane systems, high curing temperature is still an issue. On the other hand, powder coating systems make it possible to reduce the costs and enhance the process of forming complex 3D structures using the deep drawing method by pre-coated metal substrates. During this processing method, there is a probability of micro crack formation in the coated film due to strain impact on the coating layer. A powder coating with self-healing ability is an ultimate solution to face not only this kind of fraction but also any other possible ones (such as defects caused by any impact on film surface during processing, transporting or even service). Here, a single molecule that is prepared via Diels–Alder cycloaddition reaction and retro Diels–Alder cleavage reaction was utilized as a self-healing additive to achieve self-healing ability in the powder coating system that is based on a commercially available uretdione cross-linker and OH-polyester resin. Coatings were prepared through melt mixing of components in a lab mixer, milling, sieving, and then application on the metal substrate through the electrostatic spraying method. To illustrate the role of self-healing additive, various concentrations (4 and 9% wt.) in combination with different curing temperatures (80 °C to 200 °C) were investigated. Both samples containing HA showed self-healing ability at elevated temperature around 120 °C for about 30 min with acceptable roughness and surface properties. Hardness measurement of cured film as well as thermal investigation indicate the chemical reaction of HA in a cross-linked network of cross-linker and resin. In addition, using HA leads to a 40 K drop in curing temperature of the system without using any catalyst. A 2.58% improvement in hardness values at a lower curing temperature and healing time of around 12.5 min at 120 °C to recover 100% of initial scratch (more than 10 cycles) in the sample containing 9% wt. HA was observed. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Figure 1

Review

Jump to: Research

Open AccessReview

Chitosan as an Outstanding Polysaccharide Improving Health-Commodities of Humans and Environmental Protection

by

Lorenzo A. Picos-Corrales

,

Ana M. Morales-Burgos

,

Jose P. Ruelas-Leyva

,

Grégorio Crini

,

Evangelina García-Armenta

,

Sergio A. Jimenez-Lam

,

Lidia E. Ayón-Reyna

,

Fernando Rocha-Alonzo

,

Loranda Calderón-Zamora

,

Ulises Osuna-Martínez

,

Abraham Calderón-Castro

,

Gonzalo De-Paz-Arroyo

and

Levy N. Inzunza-Camacho

Polymers 2023, 15(3), 526; https://doi.org/10.3390/polym15030526 - 19 Jan 2023

Cited by 9 | Viewed by 2105

Abstract

Public health, production and preservation of food, development of environmentally friendly (cosmeto-)textiles and plastics, synthesis processes using green technology, and improvement of water quality, among other domains, can be controlled with the help of chitosan. It has been demonstrated that this biopolymer exhibits [...] Read more.

Public health, production and preservation of food, development of environmentally friendly (cosmeto-)textiles and plastics, synthesis processes using green technology, and improvement of water quality, among other domains, can be controlled with the help of chitosan. It has been demonstrated that this biopolymer exhibits advantageous properties, such as biocompatibility, biodegradability, antimicrobial effect, mucoadhesive properties, film-forming capacity, elicitor of plant defenses, coagulant-flocculant ability, synergistic effect and adjuvant along with other substances and materials. In part, its versatility is attributed to the presence of ionizable and reactive primary amino groups that provide strong chemical interactions with small inorganic and organic substances, macromolecules, ions, and cell membranes/walls. Hence, chitosan has been used either to create new materials or to modify the properties of conventional materials applied on an industrial scale. Considering the relevance of strategic topics around the world, this review integrates recent studies and key background information constructed by different researchers designing chitosan-based materials with potential applications in the aforementioned concerns. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Graphical abstract

Open AccessReview

Advancing Strategies of Biofouling Control in Water-Treated Polymeric Membranes

by

,

,

and

Polymers 2022, 14(6), 1167; https://doi.org/10.3390/polym14061167 - 15 Mar 2022

Cited by 13 | Viewed by 2930

Abstract

Polymeric membranes, such as polyamide thin film composite membranes, have gained increasing popularity in wastewater treatment, seawater desalination, as well as the purification and concentration of chemicals for their high salt-rejection and water flux properties. Membrane biofouling originates from the attachment or deposition [...] Read more.

Polymeric membranes, such as polyamide thin film composite membranes, have gained increasing popularity in wastewater treatment, seawater desalination, as well as the purification and concentration of chemicals for their high salt-rejection and water flux properties. Membrane biofouling originates from the attachment or deposition of organic macromolecules/microorganisms and leads to an increased operating pressure and shortened service life and has greatly limited the application of polymeric membranes. Over the past few years, numerous strategies and materials were developed with the aim to control membrane biofouling. In this review, the formation process, influence factors, and consequences of membrane biofouling are systematically summarized. Additionally, the specific strategies for mitigating membrane biofouling including anchoring of hydrophilic monomers, the incorporation of inorganic antimicrobial nanoparticles, coating/grafting of cationic bactericidal polymers, and the design of multifunctional material integrated multiple anti-biofouling mechanisms, are highlighted. Finally, perspectives on the challenges and opportunities in anti-biofouling polymeric membranes are shared, shedding light on the development of even better anti-biofouling materials in near future. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Figure 1

Open AccessReview

Recent Developments in Hyaluronic Acid-Based Hydrogels for Cartilage Tissue Engineering Applications

by

Evgenia Tsanaktsidou

,

Olga Kammona

and

Costas Kiparissides

Polymers 2022, 14(4), 839; https://doi.org/10.3390/polym14040839 - 21 Feb 2022

Cited by 21 | Viewed by 4734

Abstract

Articular cartilage lesions resulting from injurious impact, recurring loading, joint malalignment, etc., are very common and encompass the risk of evolving to serious cartilage diseases such as osteoarthritis. To date, cartilage injuries are typically treated via operative procedures such as autologous chondrocyte implantation [...] Read more.

Articular cartilage lesions resulting from injurious impact, recurring loading, joint malalignment, etc., are very common and encompass the risk of evolving to serious cartilage diseases such as osteoarthritis. To date, cartilage injuries are typically treated via operative procedures such as autologous chondrocyte implantation (ACI), matrix-associated autologous chondrocyte implantation (MACI) and microfracture, which are characterized by low patient compliance. Accordingly, cartilage tissue engineering (CTE) has received a lot of interest. Cell-laden hydrogels are favorable candidates for cartilage repair since they resemble the native tissue environment and promote the formation of extracellular matrix. Various types of hydrogels have been developed so far for CTE applications based on both natural and synthetic biomaterials. Among these materials, hyaluronic acid (HA), a principal component of the cartilage tissue which can be easily modified and biofunctionalized, has been favored for the development of hydrogels since it interacts with cell surface receptors, supports the growth of chondrocytes and promotes the differentiation of mesenchymal stem cells to chondrocytes. The present work reviews the various types of HA-based hydrogels (e.g., in situ forming hydrogels, cryogels, microgels and three-dimensional (3D)-bioprinted hydrogel constructs) that have been used for cartilage repair, specially focusing on the results of their preclinical and clinical assessment. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Graphical abstract

Open AccessReview

Study on Control of Polymeric Architecture of Sulfonated Hydrocarbon-Based Polymers for High-Performance Polymer Electrolyte Membranes in Fuel Cell Applications

by

,

,

and

Polymers 2021, 13(20), 3520; https://doi.org/10.3390/polym13203520 - 13 Oct 2021

Cited by 15 | Viewed by 4234

Abstract

Polymer electrolyte membrane fuel cell (PEMFC) is an eco-friendly energy conversion device that can convert chemical energy into electrical energy without emission of harmful oxidants such as nitrogen oxides (NO_x) and/or sulfur oxides (SO_x) during operation. Nafion^®, [...] Read more.

Polymer electrolyte membrane fuel cell (PEMFC) is an eco-friendly energy conversion device that can convert chemical energy into electrical energy without emission of harmful oxidants such as nitrogen oxides (NO_x) and/or sulfur oxides (SO_x) during operation. Nafion^®, a representative perfluorinated sulfonic acid (PFSA) ionomer-based membrane, is generally incorporated in fuel cell systems as a polymer electrolyte membrane (PEM). Since the PFSA ionomers are composed of flexible hydrophobic main backbones and hydrophilic side chains with proton-conducting groups, the resulting membranes are found to have high proton conductivity due to the distinct phase-separated structure between hydrophilic and hydrophobic domains. However, PFSA ionomer-based membranes have some drawbacks, including high cost, low glass transition temperatures and emission of environmental pollutants (e.g., HF) during degradation. Hydrocarbon-based PEMs composed of aromatic backbones with proton-conducting hydrophilic groups have been actively studied as substitutes. However, the main problem with the hydrocarbon-based PEMs is the relatively low proton-conducting behavior compared to the PFSA ionomer-based membranes due to the difficulties associated with the formation of well-defined phase-separated structures between the hydrophilic and hydrophobic domains. This study focused on the structural engineering of sulfonated hydrocarbon polymers to develop hydrocarbon-based PEMs that exhibit outstanding proton conductivity for practical fuel cell applications. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Graphical abstract

Open AccessReview

A Comprehensive Review on the Applications of Exosomes and Liposomes in Regenerative Medicine and Tissue Engineering

by

Mojtaba Shafiei

,

Mohamed Nainar Mohamed Ansari

,

Saiful Izwan Abd Razak

and

Muhammad Umar Aslam Khan

Polymers 2021, 13(15), 2529; https://doi.org/10.3390/polym13152529 - 30 Jul 2021

Cited by 30 | Viewed by 5543

Abstract

Tissue engineering and regenerative medicine are generally concerned with reconstructing cells, tissues, or organs to restore typical biological characteristics. Liposomes are round vesicles with a hydrophilic center and bilayers of amphiphiles which are the most influential family of nanomedicine. Liposomes have extensive research, [...] Read more.

Tissue engineering and regenerative medicine are generally concerned with reconstructing cells, tissues, or organs to restore typical biological characteristics. Liposomes are round vesicles with a hydrophilic center and bilayers of amphiphiles which are the most influential family of nanomedicine. Liposomes have extensive research, engineering, and medicine uses, particularly in a drug delivery system, genes, and vaccines for treatments. Exosomes are extracellular vesicles (EVs) that carry various biomolecular cargos such as miRNA, mRNA, DNA, and proteins. As exosomal cargo changes with adjustments in parent cells and position, research of exosomal cargo constituents provides a rare chance for sicknesses prognosis and care. Exosomes have a more substantial degree of bioactivity and immunogenicity than liposomes as they are distinctly chiefly formed by cells, which improves their steadiness in the bloodstream, and enhances their absorption potential and medicinal effectiveness in vitro and in vivo. In this review, the crucial challenges of exosome and liposome science and their functions in disease improvement and therapeutic applications in tissue engineering and regenerative medicine strategies are prominently highlighted. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Special Issue "Feature Papers in Polymer Physics and Theory"

Share This Special Issue

Special Issue Editors

Special Issue Information

Published Papers (11 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI