Review: Poly(vinyl alcohol) Functionalizations and Applications

Functionalizations of poly(vinyl alcohol) congruent with the desired applications are discussed inthis article. The chemical modifications of poly(vinyl alcohol) with different molecular weights and hydrolysis degrees via conventional chemistries, namely esterification, carbamation, and etherification, and via the modern ones such as click chemistry, led to finished materials with a wide range of applications and uses: membrane fuel cells, biologicals and biomedicals, adsorption of heavy metals and other contaminants, molecular sensing or chemosensor for detection of some useful molecules or toxic ones, separation of mixtures, and catalysis in organic and inorganic syntheses. Different forms of the duly modified poly(vinyl alcohol)s were used in such applications, including hydrogels, films, membranes, and nanoparticles. The incorporated modifying agents onto poly(vinyl alcohol) matrixes brought some changes that were in tune with the projected applications. These modifying agents were not confined to molecular compounds but also to macromolecular ones which are graphene, hyaluronic acid, β-cylcodextrin, polystyrene, poly(4-vinylpyridine), and poly(L-lactic acid).     

New modifications of poly(vinyl alcohol)s and their applications

Poly(vinyl alcohol) (PV-OH), prepared from poly(viny) acetate), is used widely in many industries. Various grades have been produced, with different degree of polymerization and degree of hydrolysis. Recently, novel modified (PV-OH)s with anion, cation, silanol or hydrophobic groups have been studied and developed. They have new properties in addition to those of ordinary PV-OH and have new applications. The methods of modification and the characteristics and some applications of the modified polymers are described.     

Vinyl molding compounds: Formulation and performance evaluation

Today's vinyl molding compounds are successfully meeting the combined challenges of physical properties, appearance, processability, and cost requirements in a variety of specialty injection molding applications such as appliance parts, business equipment, and electrical enclosures. One of the major reasons why vinyl materials are so versatile is that the poly(vinyl chloride) resins on which they are based can be easily modified with a wide variety of additives to tailor the particular performance features of the compounds to their intended applications. Determination of an appropriate combination of PVC resin and additives to produce an effective and cost-competitive compound, however, is not a simple process. Important considerations in formulating a vinyl molding compound and evaluating its performance are discussed here.     

Melt processible fluoropolymer composites

A series of melt-processible fluoropolymer compounds including ethylene-tetrafluoroethylene (ETFE), poly(vinylidene fluoride) (PVF₂), ethylene-chlorotrifluoroethylene copolymer (ECTFE), perfluoroalkoxy modified tetrafluoroethylene (PFA), and fluorinated ethylene-propylene copolymer (FEP) containing reinforcing glass fiber, milled glass fiber, carbon fiber, minerals, poly(tetrafluoroethylene) (PTFE) lubricant powder, graphite powder and MoS₂ were prepared and characterized. The mechanical, physical, thermal, and tribiological properties of these composites were compared and ranked for suitability in various applications. These composites represent the first comprehensive evaluation of reinforced and filled meltprocessible fluoropolymer composites.     

Microbial susceptibility of various polymers and evaluation of thermoplastic elastomers with antimicrobial additives

The incursion of microbial growth on polymeric products can deteriorate their performance and lead to the development of undesirable staining and odors. A growing trend in the industry has aimed to reduce microbial populations on high-touch surfaces via the use of antimicrobials to protect material aesthetics and durability or to prevent the spread of pathogenic microorganisms. In this study, a variety of plastic substrates (30 unique polymer compounds), including poly(acrylonitrile-co-butadiene-co-styrene), poly(butylene terephthalate), poly(etherimide), various thermoplastic elastomers (TPEs), poly(carbonates), and poly(amides), were screened for susceptibility to microbial attack using American Society for Testing and Materials (ASTM) G21 (fungi susceptibility), Japanese Industrial Standard (JIS) Z2801, and modified ASTM E1428-15a (bacterial susceptibility) test standards. TPEs were determined to be most susceptible to microbial attack under the appropriate environmental conditions. Subsequent studies assessed the use of an antimicrobial additive, zinc pyrithione (ZPT), for potential efficacy in a variety of TPE blends for diverse target market applications. ZPT proved to be very effective in protecting TPEs, reducing Staphylococcus aureus and Escherichia coli populations by 99.9% or more in JIS Z2801 testing and inhibiting fungal growth (rating = 0) according to the ASTM G21 standard.     

芳香族聚酰胺纤维与CR NBR及其并用胶料粘合技术研究

芳香族聚酰胺纤维(简称芳纶)通过浸渍改性环氧树脂(SJR-2)和预缩合间苯二酚-甲醛树脂(SJR-1)的水溶液,再经半固化,实现了对其表面的粘合活化处理。用这种经活化的芳纶复丝捻成的帘线,只浸一次由SJR-1配制的间苯二酚-甲醛胶乳,即可获得与CR,NBR及其并用胶料的优良的粘合活性,而且提高了帘线的动态力学性能。     

Modification of poly(ethylene ether carbonate) polyols by transesterification

Poly(ethylene ether carbonate) polyols are the reaction products of alkylene carbonates or alkylene oxides and CO₂ with alcoholic initiators. These polyols can be modified with aliphatic hydroxyl compounds by transesterification reactions. The modifier becomes chemically bound into the polymer during reaction and modifies the properties of the polyol. The extent of reaction is very easy to follow by size exclusion chromatography. Molecular weight is controlled by the molecular weight of the reactants and by their stoichiometry. This transesterification process is compared to the previously described transesterification/advancement process. The transesterification process has the advantage of using milder temperature conditions and runs at ambient pressures. Therefore, modifiers can be used in the transesterification process that are unstable or undergo different chemistry under the reaction conditions of the transesterification/advancement process. Although the modifiers used in the transesterification/advancement process must be less volatile than DEG, more volatile modifiers can be used in the transesterification process. The two processes compliment each other, allowing the preparation of a wide variety of modified poly(ethylene ether carbonate) polyols. These polyols are useful in polyurethane applications.     

Investigation of modified SEBS‐based thermoplastic elastomers by temperature scanning stress relaxation measurements

Thermoplastic elastomers (TPEs) based on poly(styrene‐b‐ethylene/butylene‐b‐styrene) (SEBS), modified with poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE), were investigated by a new testing method. The development and characterization of TPEs with improved temperature and oil resistance is a current area of research to extend the applications of TPEs, especially in the automotive industry. Thermal scanning stress relaxation (TSSR) was used to investigate the relaxation behavior of compounds containing SEBS, blended with extender oil, various amounts of PPE and in some cases with a thermoplastic polymer. Polyamide 12 (PA12) or polypropylene (PP) were used as the thermoplastic component. TSSR measurements were applied to detect relaxation changes in the glass transition region of the polystyrene blocks mixed with PPE. It was shown that the glass transition temperature increased with addition of PPE to the compound up to a limit of approximately 150°C, which corresponded to a weight fraction of PPE in the polystyrene (PS)‐block of 0.5. The increased glass transition temperature lead to SEBS‐based thermoplastic elastomer compounds with improved upper service temperatures. Phase images obtained by atomic force microscopy showed that the addition of PPE results in an increase of hard phase dimension. The addition of a thermoplastic polymer improved the mechanical properties and temperature resistance, but naturally decreased the elasticity of the compounds. Compounds containing PA12 exhibited an improved oil resistance. POLYM. ENG. SCI., 45:1498–1507, 2005. © 2005 Society of Plastics Engineers     

Miscibility of poly(vinyl acetate) and vinyl acetate-ethylene copolymers with styrene-acrylic acid and acrylate-acrylic acid copolymers

Poly(vinyl acetate) and vinyl acetate-ethylene (VAE) copolymers compose one of the more important polymeric materials, widely employed in coating and adhesive applications. A new class of miscible polymer blends involving poly(vinyl acetate) and VAE with styrene-acrylic acid and acrylate-acrylic acid copolymers has been found. Experimental windows of miscibility as a function of the ethylene content for VAE copolymers and the acrylic acid content of the acrylate-acrylic acid copolymers are observed (acrylate = methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate). Employing well-established analog heat of mixing measurements, predicted windows of miscibility were compared with experimental results. Fair qualitative agreement was observed and supported the hypothesis that specific rejection arguments can be employed to explain the observed miscibility. Failure to quantitatively predict miscibility based on the analog heat of mixing measurements may be due to the higher association tendencies of the model compounds relative to acrylic acid units in the high molecular weight polymers. No miscible combinations were found for methyl methacrylate-acrylic acid copolymers or acrylate-methacrylic acid copolymers in admixture with poly(vinyl acetate) or the VAE copolymers, thus indicating the sensitivity of phase behavior to minor structural changes. VAE (30 wt % ethylene) copolymers were also noted to be miscible with several polymers previously noted to be miscible with poly(vinyl acetate), namely, poly(vinylidene fluoride), poly(ethylene oxide), and nitrocellulose. © 1995 John Wiley & Sons, Inc.     

聚酰胺-胺树枝状高分子及其研究进展

介绍聚酰胺胺树枝状高分子的结构和性能,聚酰胺胺的特殊结构决定了其独特的物化性质。同时,对其合成方法、及其经改性后的树枝状高分子在生物医药、表面活性剂、催化剂、污水处理和膜材料等方面的应用研究进展进行了综述。     

Preparation of zinc oxide nanocrystals with high stability in the aqueous phase

ZnO nanocrystals (NCs), potential candidates for photoluminescent applications, have attracted increasing attention recently because of their good biocompatibility, low cost, and convenient synthesis. However, their stability and fluorescent quenching, particularly in the aqueous phase, still hampers their use in biological applications. We report herein the synthesis of ZnO NCs modified by amphiphilic methoxy poly(ethylene glycol)‐grafted poly(styrene‐alt‐maleic anhydride) (SMA‐g‐MPEG) copolymer based on the sol–gel method. We demonstrated a simple solution to address those challenges. Compared with unmodified ZnO NCs, SMA‐g‐MPEG modified ZnO NCs exhibited a significantly improvement in the stability and photoluminescent properties in the aqueous phase over current unmodified ones. This simple synthesis provides a novel platform for the preparation of ZnO NCs for biological applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Catalytic hydroformylation and hydrocarboxylation of unsaturated fatty compounds

The two catalyst systems rhodium-triphenylphosphine and palladium chloride-triphenylphosphine were investigated for the respective hydroformylation and hydrocarboxylation of oleic acid or ester to produce C-19 bifunctional compounds. Compared to conventional cobalt carbonyl for making formylstearate, rhodium-triphenylphosphine permits lower pressures (1000–2000 psi vs. 3000–4000 psi), higher conversions (95% vs. 80%), and no loss of functionality (vs. 15% hydrogenation with cobalt). Although palladium chloride-triphenylphosphine for hydrocarboxylation introduces the carboxyl function directly into the fatty acid chain, CO pressures of 3000–4000 psi and corrosion-resistant equipment are necessary. When applied to polyunsaturated fatty acids, both rhodium and palladium catalyst systems have the outstanding advantage of introducing functionality at each double bond position to produce polyformyl- and polycarboxystearates. Selected formyl derivatives were converted in excellent yield to acetals, to acids and their esters, to hydroxymethyl compounds and their esters, and also to aminomethyl compounds that could be condensed to polyamides. Several of the esters and acetals were effective primary plasticizers for poly(vinyl chloride) that had outstanding low volatility characteristics. Other applications for these new and highly versatile derivatives included rigid urethane foams, urethane-modified coatings, ester lubricants, and a shrink-resist treatment for wool.     

Effect of aggregation states on some properties of PVC solids and melts

Plasticized compounds of poly(vinyl chloride) (PVC) have been prepared using PVC polymer as supplied and as recovered from solutions in tetrahydrofuran. Mechanical properties and melt elasticity measurements were found to vary significantly among these compounds. It is proposed that the solid-state characteristics and melt elasticity parameters in these compounds depend on the state of chain entanglement and that the entanglement state can be modified significantly by procedures such as used here. Annealing experiments have shown that the rates of attaining property equilibria—symptomatic of equilibrium entanglement states—are dependent on diffusion processes. Neither solution-modified nor control PVC compounds are in steady states when first tested; consequently, time-dependent property variations may be expected as morphological steady states are attained at conventional use temperatures for PVC compounds. The present study extends to PVC the principles of entanglement network modification through solution, or shearing processes, as a means of selecting preferred property balances in melt processing and mechanical properties. That principle had earlier been shown to apply to polyethylenes.     

Hemocompatibility of polymers for use in vascular endoluminal implants

Implanted polymers for cardiovascular applications may function as structural supports, barriers, or provide a means for local drug delivery. Several thermoplastic biodegradable drug delivery polymers are potential candidates for blood-contacting implant applications. For intravascular applications specifically, a criterion for material selection is the intrinsic hemocompatibility of the baseline polymer. As an initial screening approach for selection of polymers for in vivo use, thin films of polyesters: poly(ɛ-caprolactone) (PCL), poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA); polyanhydrides: poly(fatty acid dimer-co-sebacic acid) (PFAD:SA) and poly(biscarboxyphenoxypropane-co-sebacic acid) (PCPP:SA); and poly(ethylene glycol) (PEG)-ylated polyesters: PLA:PEG, PCL:PEG and PCL:PLA:PEG polymers were spin-cast on glass cover slips and placed in an in vitro flow system exposing them at a controlled shear to overflowing human whole blood. Platelet adherence, aggregate formation, and thrombus formation, as well as leukocyte adherence were assessed following 5 min of flow. At 5 min of flow the rank order of materials, in terms of least to most thrombogenic was: PCL < PFAD:SA < PCPP:SA < PLGA < PLA. All PEGylated materials, in general, had less thrombus formation than baseline unmodified materials.     

Bioresorbable polymers for temporary therapeutic applications

Polymer science is mature enough to allow one to think about tailor-making macromolecular compounds aimed at interacting purposely with living systems. Reasons for developing bioresorbable polymers for temporary therapeutic applications are discussed with respect to property adjustments and economical factors. The field of the applications is first described and guidelines for tailor-making multimeric macromolecules with desired properties are presented. The approach led to focuss investigations on poly(α-hydroxy acids) and functional poly(β-hydroxy acids) derived from natural hydroxy acids, namely lactic, glycolic and malic acids. Physical, mechanical and biological properties of some corresponding polymers and copolymers are presented. Last but not least, examples of applications currently investigated are recalled.     

丙烯酸乙酯改性硅油的合成和性能研究

以含氢硅油(PHMS)和丙烯酸乙酯(EA)为原料,制得兼有二者性能的丙烯酸乙酯改性硅油。研究了PHMS含氢量和粘度对产品性能的影响,并用二元回归分析法进一步分析了PHMS含氢量和粘度与产品性能的关系。结果表明,PHMS含氢量对产品性能影响比其粘度显著,且PHMS含氢量和粘度越小,产品的性能越佳,其粘温系数为0.61,表面张力为21.2 mN/m。且二元回归方程分别预测了产品的粘度指数、粘温系数和表面张力,误差绝对值分别控制在7.411 8,0.009 1和0.095 3 mN/m内。     

Toughening of epoxy resin by functional‐terminated polyurethanes and/or semicrystalline polymer powders

Hydroxyl‐, amine‐, and anhydride‐terminated polyurethane (PU) prepolymers, which were synthesized from polyether [poly(tetramethylene glycol)] diol, 4,4′‐diphenylmethane diisocyanate, and a coupling agent, bisphenol‐A (Bis‐A), 4,4′‐diaminodiphenyl sulphone (DDS), or benzophenonetetracarboxylic dianhydride, were used to modify the toughness of Bis‐A diglycidyl ether epoxy resin cured with DDS. Besides the crystalline polymers, poly(butylene terephthalate) (PBT) and poly(hexamethylene adipamide) (nylon 6,6), with particle sizes under 40 μm were employed to further enhance the toughness of PU‐modified epoxy at a low particle content. As shown by the experimental results, the modified resin displayed a significant improvement in fracture energy and also its interfacial shear strength with polyaramid fiber. The hydroxyl‐terminated PU was the most effective among the three prepolymers. The toughening mechanism is discussed based on the morphological and the dynamic mechanical behavior of the modified epoxy resin. Fractography of the specimen observed by the scanning electron microscopy revealed that the modified resin had a two‐phase structure. The fracture properties of PBT‐particle‐filled epoxy were better than those of nylon 6,6‐particle‐filled epoxy. Nevertheless, the toughening effect of these crystalline polymer particles was much less efficient than that of PU modification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2903–2912, 2001     

Modeling the phase behavior in binary mixtures involving blowing agents and thermoplastic resins

The thermophysical properties of mixtures of thermoplastic resins and blowing agents, together with the knowledge of the solubilities of these components, are the basis for the manufacturing of plastic foams. In this work, the solubilities of blowing agents trichlorofluoromethane, dichlorodifluoromethane, chlorodifluoromehane, and 1,2‐dichloro‐1,1,2,2‐tetrafluoroethane in thermoplastic resins poly(styrene), high density poly(ethylene), low density poly(ethylene), poly(propylene), poly(vinyl chloride), poly(carbonate) and poly(propylene oxide) were modeled by using the Perturbed Chain‐Statistical Associating Fluid Theory (PC‐SAFT) and the Sánchez‐Lacombe equations of state (EoS), fitting a single temperature‐dependent binary interaction parameter. PC‐SAFT is a theoretically based equation of state with three pure component parameters that describe efficiently the thermodynamics of complex systems. Earlier works with this EoS have already predicted the phase coexistence properties of various refrigerants and higher order alkane series compounds, along with their mixtures. The pure component parameters for the blowing agents were obtained by regression of vapor pressure and liquid density data, while the pure component parameters for the thermoplastic resins were obtained by regression of pure liquid PVT data. The parameter estimation was performed by using a modified maximum likelihood method. The solubility results obtained with both EoS have been compared; the results from PC‐SAFT showed a higher accuracy in terms of solubility pressure deviations. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

A Comprehensive Review on the Interaction of Milk Protein Concentrates with Plant-Based Polyphenolics

Functional properties and biological activities of plant-derived polyphenolic compounds have gained great interest due to their epidemiologically proven health benefits and diverse industrial applications in the food and pharmaceutical industry. Moreover, the food processing conditions and certain chemical reactions such as pigmentation, acylation, hydroxylation, and glycosylation can also cause alteration in the stability, antioxidant activity, and structural characteristics of the polyphenolic compounds. Since the (poly)phenols are highly reactive, to overcome these problems, the formulation of a complex of polyphenolic compounds with natural biopolymers is an effective approach. Besides, to increase the bioavailability and bioaccessibility of polyphenolic compounds, milk proteins such as whey protein concentrate, sodium caseinate, and milk protein concentrate act as natural vehicles, due to their specific structural and functional properties with high nutritional value. Therefore, milk proteins are suitable for the delivery of polyphenols to parts of the gastrointestinal tract. Therefore, this review reports on types of (poly)phenols, methods for the analysis of binding interactions between (poly)phenols–milk proteins, and structural changes that occur during the interaction.     

Biodegradable polymers exhibiting temperature-responsive sol–gel transition as injectable biomedical materials

Injectable biodegradable copolymer hydrogels, which exhibit temperature-responsive sol-to-gel transition, have recently drawn much attention as promising biomedical materials such as drug delivery, cell implantation, and tissue engineering. These injectable hydrogels can be implanted in the human body with minimal surgical invasion. Temperature-responsive gelling copolymers usually possess block- and/or branched architectures and amphiphilicity with a delicate hydrophobic/hydrophilic balance. Poly(ethylene glycol) (PEG) has typically been used as hydrophilic segments due to its biocompatibility and temperature-dependent dehydration nature. Aliphatic polyesters such as polylactide, poly(lactide-co-glycolide), poly(ε-caprolactone), and their modified copolymers have been used as hydrophobic segments based on their biodegradability and biocompatibility. Copolymers of PEG with other hydrophobic polymers such as polypeptides, polydepsipeptides have also been recently reported as injectable hydrogels. In this review, brief history and recent advances in injectable biodegradable polymer hydrogels are summarized especially focusing on the relationship between polymer architecture and their gelation properties. Moreover, the applications of these injectable polymer gels for biomedical use such as drug delivery and tissue engineering are also described.