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Polymers, Volume 7, Issue 7 (July 2015) – 10 articles , Pages 1192-1378

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3936 KiB  
Review
From Self-Assembled Monolayers to Coatings: Advances in the Synthesis and Nanobio Applications of Polymer Brushes
by Myungwoong Kim, Samantha K. Schmitt, Jonathan W. Choi, John D. Krutty and Padma Gopalan
Polymers 2015, 7(7), 1346-1378; https://doi.org/10.3390/polym7071346 - 20 Jul 2015
Cited by 99 | Viewed by 23191
Abstract
In this review, we describe the latest advances in synthesis, characterization, and applications of polymer brushes. Synthetic advances towards well-defined polymer brushes, which meet criteria such as: (i) Efficient and fast grafting, (ii) Applicability on a wide range of substrates; and (iii) Precise [...] Read more.
In this review, we describe the latest advances in synthesis, characterization, and applications of polymer brushes. Synthetic advances towards well-defined polymer brushes, which meet criteria such as: (i) Efficient and fast grafting, (ii) Applicability on a wide range of substrates; and (iii) Precise control of surface initiator concentration and hence, chain density are discussed. On the characterization end advances in methods for the determination of relevant physical parameters such as surface initiator concentration and grafting density are discussed. The impact of these advances specifically in emerging fields of nano- and bio-technology where interfacial properties such as surface energies are controlled to create nanopatterned polymer brushes and their implications in mediating with biological systems is discussed. Full article
(This article belongs to the Special Issue Advances in Polymer Brushes)
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2443 KiB  
Article
Preparation and Properties of Cellulose Laurate (CL)/Starch Nanocrystals Acetate (SNA) Bio-nanocomposites
by Feng-Yuan Huang, Xiao-Jie Wu, Yan Yu and Yan-Hua Lu
Polymers 2015, 7(7), 1331-1345; https://doi.org/10.3390/polym7071331 - 14 Jul 2015
Cited by 13 | Viewed by 10174
Abstract
In the present paper, a series of totally novel bio-nanocomposite films from cellulose laurate (CL) and starch nanocrystals acetate (SNA) were fabricated, and the properties of nanocomposite films were investigated in detail. SNA was obtained by modifying starch nanocrystals (SNs) produced by sulfuric [...] Read more.
In the present paper, a series of totally novel bio-nanocomposite films from cellulose laurate (CL) and starch nanocrystals acetate (SNA) were fabricated, and the properties of nanocomposite films were investigated in detail. SNA was obtained by modifying starch nanocrystals (SNs) produced by sulfuric acid hydrolysis of corn starch with acetic anhydride. The favorable dispersity of SNA in chloroform made it ready to convert into nanocomposite films with CL via casting/evaporation method. The transmittance, thermal behavior, mechanical properties, barrier properties and hydrophobicity of CL/SNA nanocomposite films were investigated with UV-vis spectrophotometer, simultaneous thermal analyzer (STA), universal tensile tester/dynamic thermomechanical analysis (DMA), water vapor permeation meter/oxygen permeability tester, and contact angle tester, respectively. The transmittance of nanocomposite films decreased with the increase of SNA content. Thermogravimetric analysis (TGA) results showed that the introduction of SNA into CL matrix did not severely decrease the thermal behavior of CL/SNA nanocomposites. Moreover, non-linear and linear mechanical analysis reflected the enhancement of SNA. At lower contents of SNA (<5.0 wt%), the values of Young’s modulus, tensile strength and the elongation at break of nanocomposite films were comparable with those of neat CL. However, with the increase of SNA, the Young’s modulus and tensile strength were improved significantly and were accompanied by the decreased elongation at break. The water vapor permeability (WVP) and oxygen permeability (PO2) of CL/SNA nanocomposite films were significantly improved by the addition of SNA. Full article
(This article belongs to the Collection Polysaccharides)
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3109 KiB  
Article
Structural Performance of Polymer Fiber Reinforced Engineered Cementitious Composites Subjected to Static and Fatigue Flexural Loading
by Mohamed A.A. Sherir, Khandaker M.A. Hossain and Mohamed Lachemi
Polymers 2015, 7(7), 1299-1330; https://doi.org/10.3390/polym7071299 - 14 Jul 2015
Cited by 45 | Viewed by 6557
Abstract
This paper presents the influence of silica sand, local crushed sand and different supplementary cementing materials (SCMs) to Portland cement (C) ratio (SCM/C) on the flexural fatigue performance of engineered cementitious composites (ECCs). ECC is a micromechanically-based designed high-performance polymer fiber reinforced concrete [...] Read more.
This paper presents the influence of silica sand, local crushed sand and different supplementary cementing materials (SCMs) to Portland cement (C) ratio (SCM/C) on the flexural fatigue performance of engineered cementitious composites (ECCs). ECC is a micromechanically-based designed high-performance polymer fiber reinforced concrete with high ductility which exhibits strain-hardening and micro-cracking behavior in tension and flexure. The relative high cost remains an obstacle for wider commercial use of ECC. The replacement of cement by SCMs, and the use of local sand aggregates can lower cost and enhance greenness of the ECC. The main variables of this study were: type and size of aggregates (local crushed or standard silica sand), type of SCMs (fly ash “FA” or slag), SCM/cement ratio of 1.2 or 2.2, three fatigue stress levels and number of fatigue cycles up to 1 million. The study showed that ECC mixtures produced with crushed sand (with high volume of fly ash and slag) exhibited strain hardening behavior (under static loading) with deformation capacities comparable with those made with silica sand. Class F-fly ash combined with crushed sand was the best choice (compared to class CI fly ash and slag) in order to enhance the ECC ductility with slag–ECC mixtures producing lowest deflection capacity. FA–ECC mixtures with silica sand developed more damage under fatigue loading due to higher deflection evolution than FA–ECC mixtures with crushed sand. Full article
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1823 KiB  
Review
Turbulent Drag Reduction with Polymers in Rotating Disk Flow
by Cheng Hai Hong, Chun Hag Jang and Hyoung Jin Choi
Polymers 2015, 7(7), 1279-1298; https://doi.org/10.3390/polym7071279 - 13 Jul 2015
Cited by 20 | Viewed by 8674
Abstract
The frictional drag in turbulent flow can be drastically reduced by the addition of minute amounts of suitable linear flexible high-molecular-weight polymers, and the various physical characteristics of the polymers used are known to be closely related to the drag reduction efficiency. This [...] Read more.
The frictional drag in turbulent flow can be drastically reduced by the addition of minute amounts of suitable linear flexible high-molecular-weight polymers, and the various physical characteristics of the polymers used are known to be closely related to the drag reduction efficiency. This feature article briefly reviews polymer additives and factors in the system affecting turbulent drag reduction in external flow, more specifically in a rotating disk flow. Full article
(This article belongs to the Collection Featured Mini Reviews in Polymer Science)
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1218 KiB  
Communication
pH-Dependent Release of Insulin from Layer-by-Layer-Deposited Polyelectrolyte Microcapsules
by Kentaro Yoshida, Tetsuya Ono, Yoshitomo Kashiwagi, Shigehiro Takahashi, Katsuhiko Sato and Jun-ichi Anzai
Polymers 2015, 7(7), 1269-1278; https://doi.org/10.3390/polym7071269 - 13 Jul 2015
Cited by 28 | Viewed by 7616
Abstract
Insulin-containing microcapsules were prepared by a layer-by-layer (LbL) deposition of poly(allylamine hydrochloride) (PAH) and polyanions, such as poly(styrenesulfonate) (PSS), poly(vinyl sulfate) (PVS), and dextran sulfate (DS) on insulin-containing calcium carbonate (CaCO3) microparticles. The CaCO3 core was dissolved in diluted HCl [...] Read more.
Insulin-containing microcapsules were prepared by a layer-by-layer (LbL) deposition of poly(allylamine hydrochloride) (PAH) and polyanions, such as poly(styrenesulfonate) (PSS), poly(vinyl sulfate) (PVS), and dextran sulfate (DS) on insulin-containing calcium carbonate (CaCO3) microparticles. The CaCO3 core was dissolved in diluted HCl solution to obtain insulin-containing hollow microcapsules. The microcapsules were characterized by scanning electron microscope (SEM) and atomic force microscope (AFM) images and ζ-potential. The release of insulin from the microcapsules was faster at pH 9.0 and 7.4 than in acidic solutions due to the different charge density of PAH. In addition, insulin release was suppressed when the microcapsules were constructed using PAH with a lower molecular weight, probably owing to a thicker shell of the microcapsules. The results suggested a potential use of the insulin-containing microcapsules for developing insulin delivery systems. Full article
(This article belongs to the Special Issue Polymers and Polymeric Nanoparticles for Therapy and Imaging)
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2767 KiB  
Article
Synthesis of Hyperbranched Poly(ε-caprolactone) Containing Terminal Azobenzene Structure via Combined Ring-Opening Polymerization and “Click” Chemistry
by Xiaoqiang Xue, Jing Yang, Wenyan Huang, Hongjun Yang and Bibiao Jiang
Polymers 2015, 7(7), 1248-1268; https://doi.org/10.3390/polym7071248 - 09 Jul 2015
Cited by 18 | Viewed by 8664
Abstract
A novel well-defined linear poly(ε-caprolactone) (P1) containing terminal azobenzene and ethyne groups was successfully synthesized through tin-catalyzed ring-opening polymerization of ε-caprolactone in the presence of N,N′-bis(2-hydroxyethyl)-4-(3-ethynylphenylazo)aniline (BHA) in bulk. Subsequent reactions allowed the synthesis of the corresponding bromoester end-functionalized polymer [...] Read more.
A novel well-defined linear poly(ε-caprolactone) (P1) containing terminal azobenzene and ethyne groups was successfully synthesized through tin-catalyzed ring-opening polymerization of ε-caprolactone in the presence of N,N′-bis(2-hydroxyethyl)-4-(3-ethynylphenylazo)aniline (BHA) in bulk. Subsequent reactions allowed the synthesis of the corresponding bromoester end-functionalized polymer (P2), which was converted into AB2 type polymer (P3) containing terminal azide groups with NaN3. Consequently, hyperbranched poly(ε-caprolactone) (HPCL) was prepared with AB2 macromonomer (P3) by “click” chemistry under the catalysis of CuSO4·5H2O/sodium ascorbate/H2O. The structure of the resultant HPCL was characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance (1H-NMR), ultraviolet-visible (UV-Vis) spectroscopy and fourier transform infrared spectroscopy (FT-IR). Thermal and crystallization properties of P1 and HPCL were further studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and polarised optical microscopy (POM). These results indicated that the crystallinity of HPCL was slightly lower than that of P1 due to the hyperbranched structure of HPCL. Additionally, the photo-induced trans-cis isomerization behaviors of BHA, P1 and HPCL containing terminal azobenzene were investigated in chloroform solution, and the photoisomerization rate constant (kexp) of small molecule (BHA) was nearly three times faster than that of polymers P1 and HPCL, which was due to the sterically hindering effect of the polymer-chain configuration. Full article
(This article belongs to the Special Issue Precision Polymer Synthesis)
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1001 KiB  
Article
Poly(butylene succinate) Ionomers with Enhanced Hydrodegradability
by Mayka Bautista, Antxon Martínez De Ilarduya, Abdelilah Alla and Sebastián Muñoz-Guerra
Polymers 2015, 7(7), 1232-1247; https://doi.org/10.3390/polym7071232 - 09 Jul 2015
Cited by 23 | Viewed by 7522
Abstract
A series of poly(butylene succinate) (PBS) ionomers containing up to 14 mol% of sulfonated succinate units have been synthesized by polycondensation in the melt-phase. The copolyesters were obtained with weight average molecular weights oscillating between 33,000 and 72,000 g·mol−1. All copolyesters [...] Read more.
A series of poly(butylene succinate) (PBS) ionomers containing up to 14 mol% of sulfonated succinate units have been synthesized by polycondensation in the melt-phase. The copolyesters were obtained with weight average molecular weights oscillating between 33,000 and 72,000 g·mol−1. All copolyesters were semicrystalline with melting temperatures and enthalpies decreasing and glass transition temperatures increasing with the content of ionic units. The thermal stability of PBS was slightly reduced by the incorporation of these units, and it was also found that the copolyesters were stiffer but also more brittle than PBS. The hydrolytic degradability of PBS was enhanced by copolymerization, an effect that was much more pronounced in basic media. Full article
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3124 KiB  
Article
Thermal Conductivity and Specific Heat Capacity of Dodecylbenzenesulfonic Acid-Doped Polyaniline Particles—Water Based Nanofluid
by Tze Siong Chew, Rusli Daik and Muhammad Azmi Abdul Hamid
Polymers 2015, 7(7), 1221-1231; https://doi.org/10.3390/polym7071221 - 07 Jul 2015
Cited by 31 | Viewed by 8173
Abstract
Nanofluid has attracted great attention due to its superior thermal properties. In this study, chemical oxidative polymerization of aniline was carried out in the presence of dodecylbenzenesulfonic acid (DBSA) as a dopant. Particles of DBSA-doped polyaniline (DBSA-doped PANI) with the size range of [...] Read more.
Nanofluid has attracted great attention due to its superior thermal properties. In this study, chemical oxidative polymerization of aniline was carried out in the presence of dodecylbenzenesulfonic acid (DBSA) as a dopant. Particles of DBSA-doped polyaniline (DBSA-doped PANI) with the size range of 15 to 50 nm were obtained, as indicated by transmission electron microscope (TEM). Results of ultra violet-visible (UV-Vis) absorption and Fourier transform infrared (FTIR) spectroscopies as well as thermogravimetric analysis showed that PANI nanoparticles were doped with DBSA molecules. The doping level found was 36.8%, as calculated from elemental analysis data. Thermal conductivity of water was enhanced by 5.4% when dispersed with 1.0 wt% of DBSA-PANI nanoparticles. Specific heat capacity of water-based nanofluids decreased with increasing amount of DBSA-PANI nanoparticles. Full article
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2513 KiB  
Article
Improved Method for Preparation of Amidoxime Modified Poly(acrylonitrile-co-acrylic acid): Characterizations and Adsorption Case Study
by Nur Amirah Mohd Zahri, Siti Nurul Ain Md Jamil, Luqman Chuah Abdullah, Thomas Choong Shean Yaw, Mohsen Nourouzi Mobarekeh, Jia Huey Sim and Nur Salimah Mohd Rapeia
Polymers 2015, 7(7), 1205-1220; https://doi.org/10.3390/polym7071205 - 02 Jul 2015
Cited by 35 | Viewed by 12244
Abstract
Redox polymerization of poly(acrylonitrile-co-acrylic acid) (poly(AN-co-AA)) is performed at 40 °C under N2 gas by varying the ratio of acrylonitrile (AN) and acrylic acid (AA) in the feed. The yield production of poly(acrylonitrile) (PAN) is 73% and poly(AN- [...] Read more.
Redox polymerization of poly(acrylonitrile-co-acrylic acid) (poly(AN-co-AA)) is performed at 40 °C under N2 gas by varying the ratio of acrylonitrile (AN) and acrylic acid (AA) in the feed. The yield production of poly(acrylonitrile) (PAN) is 73% and poly(AN-co-AA) with a feed ratio of 93:7 is the highest yield (72%). The PAN and poly(AN-co-AA) are further chemically modify with hydroxylamine hydrochloride. The FTIR spectroscopy is used to confirm the copolymerization of poly(AN-co-AA) and chemical modification of poly(AN-co-AA). Elemental microanalysis shows that the overall trend percentage of carbon, hydrogen, and nitrogen for all feed ratios are slightly decreasing as the feed ratio of AA is increasing except for poly(AN-co-AA) 93:7. The SEM images shows that spherical diameter of poly(AN-co-AA) is smaller compared to the PAN and amidoxime (AO) modified poly(AN-co-AA). The TGA (thermogravimetric analysis) analysis reveals that the poly(AN-co-AA) degrades at lower temperatures compared to the PAN but higher than AO modified poly(AN-co-AA). The case study adsorption test showed that the AO modified poly(AN-co-AA) 93:7 had the highest percentage removal of Cd2+ and Pb2+. Full article
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1758 KiB  
Article
Synthesis and Characterization of Alternating Polymers Incorporating Boron-Chelated Heterochrysene Units
by Hailei Zhang, Shuli Ma, Dongqin Li, Yonggang Wu and Xinwu Ba
Polymers 2015, 7(7), 1192-1204; https://doi.org/10.3390/polym7071192 - 25 Jun 2015
Viewed by 5990
Abstract
The novel boron-chelated π-conjugated polymers named as BF2-poly and BPh2-poly were synthesized by a feasible condensation-chelation strategy. First, conjugated polymers bearing Boc group were prepared by using palladium-catalyzed Suzuki–Miyaura coupling reaction. Then, conjugated polymers (poly-1) [...] Read more.
The novel boron-chelated π-conjugated polymers named as BF2-poly and BPh2-poly were synthesized by a feasible condensation-chelation strategy. First, conjugated polymers bearing Boc group were prepared by using palladium-catalyzed Suzuki–Miyaura coupling reaction. Then, conjugated polymers (poly-1) were obtained with high efficiency by removing the Boc group from Boc-poly. Last, boron trifluoride diethyl etherate (BF3·Et2O) or triphenylboron (BPh3) chelated with poly-1 forming the target polymers. Furthermore, the boron-chelated polymers were characterized by UV−Vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry and thermogravimetric analysis. As expected, fluorescences peaks at 520 nm and 592 nm were observed in diluted CH2Cl2. In addition, BF2-poly and BPh2-poly showed strong fluorescence at 545 nm and 601 nm in homogeneous solid state. The results coming from thermogravimetric analysis and cyclic voltammetry also revealed that the conjugated polymers have favorable electrochemical and thermostable properties. Full article
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