Synthesis and properties of unsaturated polyester diol–polyurethane hybrid polymer network

This article deals with the synthesis and properties of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] diol (PGMPD)/polyester–urethane or polyether–urethane hybrid polymer networks (HPNs). The polyurethane type and the molar ratio of NCO/OH have an effect on their properties. The structure–property relationship is discussed as well. © 1994 John Wiley & Sons, Inc.     

Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) polyols. IV. Effects of poly(propylene glycol) modified diols

A series of polyurethane elastomers with a (A{BC}_m)n type of structure have been prepared and characterized based on poly(propylene glycol) modified poly(ethylene ether carbonate) polyols, where the poly(propylene glycol) content and block length were varied systematically. Strength and modulus properties showed a marked dependence on modifier level and exhibited synergistic property improvements at 25–50 wt % modifier, relative to both unmodified poly(ethylene ether carbonate) diol and poly(propylene glycol) controls. DMA results indicated an increased modulus for the modified plaques throughout the rubbery plateau region, with higher thermal dissociation temperatures. Excellent organic solvent resistance was maintained with 25–50 wt % poly(propylene glycol) modification in the soft segment. Chemical structure of the polyurethane elastomers was established by proton and ¹³C-NMR spectroscopy. The morphology of these modified polyurethanes appears to be quite complex. Since the modified soft segments are block copolymers of blocks with a tendency toward immiscibility, some microphase separation within the soft segment domains of the polyurethane polymers might be expected. The soft segment T_g is highest where properties are maximized, suggesting changes in phase mixing. © 1992 John Wiley & Sons, Inc.     

Molecular relaxation in cross-linked poly(ethylene glycol) and poly(propylene glycol) diacrylate networks by dielectric spectroscopy

The molecular relaxation characteristics of rubbery amorphous crosslinked networks based on poly(ethylene glycol) diacrylate [PEGDA] and poly(propylene glycol) diacrylate [PPGDA] have been investigated using broadband dielectric spectroscopy. Dielectric spectra measured across the sub-glass transition region indicate the emergence of an intermediate “fast” relaxation in the highly crosslinked networks that appears to correspond to a subset of segmental motions that are more local and less cooperative as compared to those associated with the glass transition. This process, which is similar to a distinct sub-T_g relaxation detected in poly(ethylene oxide) [PEO], may be a general feature in systems with a sufficient level of chemical or physical constraint, as it is observed in the crosslinked networks, crystalline PEO, and PEO-based nanocomposites.     

Preparation and characterization of novel crosslinked poly[glycidyl methacrylate–poly(ethylene glycol) methyl ether methacrylate] as gel polymer electrolytes

In this study, glycidyl methacrylate was copolymerized with poly(ethylene glycol) methyl ether methacrylate to obtain a copolymer {poly[glycidyl methacrylate–poly(ethylene glycol) methyl ether methacrylate] [P(GMA–PEGMA)]}, which was crosslinked with α,ω‐diamino poly(propylene oxide) (Jeffamine) at various weight ratios and molecular weights to form novel gel polymer electrolytes (GPEs). The crosslinked copolymers were characterized by Fourier transform infrared spectroscopy and thermal analysis. The crosslinked polymers were amorphous in the pristine state and became crystallized after they were doped with lithium electrolyte. Furthermore, the crosslinking degree of the crosslinked polymers increased with increasing weight ratio of Jeffamine, and both the swelling properties and mechanical behaviors of the crosslinked polymers were heavily affected by the weight ratio and molecular weight of Jeffamine. The ionic conductivity (σ) of the GPEs from the crosslinked copolymers was determined by alternating‐current impedance spectroscopy. A higher molecular weight and increased weight ratio of Jeffamine resulted in a higher σ. The GPE based on P(GMA–PEGMA) crosslinked with an equal weight of Jeffamine D2000 exhibited the highest σ of 8.29 × 10⁻⁴ S/cm at 25°C and had a moderate mechanical strength. These crosslinked copolymers could be potential candidates for the construction of rechargeable lithium batteries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Photocatalytic Activity of Titania/Polydicyclopentadiene PolyHIPE Composites

Macroporous polymer composites with photocatalytic activity are prepared by the polymerization of surface modified TiO₂ nanoparticle stabilized high internal phase emulsions. Poly(ethylene glycol‐b‐propylene glycol‐b‐ethylene glycol) triblock copolymer is used to synthesize surface modified TiO₂ anatase via a sol–gel method. Macroporous composites are obtained by the ring opening metathesis polymerization of dicyclopentadiene within the particle‐stabilized high internal phase emulsion templates. Photocatalytic activity of the resulting macroporous polymer composites is described by the kinetic data of the heterogeneous photocatalytic degradation reaction of 4‐nitrophenol.     

Semi-1 thermoplastic interpenetrating polymer networks of physically crosslinked poly(n-butyl acrylate) and polystyrene

Poly(n-butyl acrylate) (PnBA) chemically crosslinked with tetraethylene glycol dimethacrylate (TEGDM) and physically crosslinked PnBAs produced by neutralization of poly(n-butyl acrylate-stat-acrylic acid) with NaOH or Ca(OH)₂ were prepared as a polymer I network. Each polymer I was swollen with styrene and cured in situ into semi-IPN-TEGDM, semi-IPN-Na, or semi-IPN-Ca, respectively. Both physically crosslinked polymers maintained their shapes during the swelling procedure. Dynamic mechanical spectroscopy indicated that good mixing of the two polymers took place in the semi-IPN-Ca as well as in semi-IPN-TEGDM, but a distinct phase separation occurred in the semi-IPN-Na. These results were supported by their transparent or optical opaque appearances, respectively. Annealing at 180°C developed further phase separation in the semi-IPN-Na, but very little in the semi-IPN-Ca. Analyses by the incompatibility number (based on the modulus–temperature curve) and the calculation of individual phase compositions (from the glass transition temperature shifts) were used in estimating the extent of molecular mixing.     

Thermotropic polymorphism of a nonphospholipid mixture: Lactylated fatty acid esters of glycerol and propylene glycol

Lactylated FA esters of glycerol and propylene glycol (LFEGPG) are a lipid blend that is commercially available and used in the food industry as an emulsifying agent. Because the mutual impact of the two different backbones on the lipid phase behavior was of particular interest, we fractionated the commercial lipid blend by column LC. Fractions with varying ratios of glycerol and propylene glycol esters were collected and characterized by MS. DSC and X-ray diffraction were applied to study the thermotropic phase behavior of the dry emulsifier and the derived lipid fractions. LFEGPG exhibited rich polymorphic behavior, adopting a sub-α-crystalline phase that converted to an α-crystalline phase. Concomitantly, a β-crystalline phase was formed by some components of this lipid mixture. We found that the fractions with the highest amounts of lipids bearing the less-polar propylene glycol as their backbone tended to form a β-crystalline phase. Also, a higher number of self-polymerized lactic acid molecules in the head group of the propylene glycol esters favored the formation of a β-crystalline phase.     

Immobilization of catalase on a novel polymer support,crosslinked polystyrene ethylene glycol acrylate resin: Role of the macromolecular matrix on enzyme activity

Crosslinked polystyrene ethylene glycol acrylate resin (CLPSER) was developed for the immobilization of the enzyme catalase by the introduction of a crosslinker, O,O′‐bis(2‐acrylamidopropyl) poly(ethylene glycol)₁₉₀₀, to styrene. The crosslinker was prepared by the treatment of acryloyl chloride with O,O′‐bis(2‐aminopropyl) poly(ethylene glycol)₁₉₀₀ in the presence of diisopropylethylamine. The resin was characterized with IR and ¹³C‐NMR spectroscopy. The catalytic activity of the catalase‐immobilized system of CLPSER was compared with divinylbenzene‐crosslinked polystyrene, ethylene glycol dimethacrylate crosslinked polystyrene, and 1,4‐butanediol dimethacrylate crosslinked polystyrene systems. Crosslink levels of 2, 8, and 20 mol % were evaluated. Among these crosslinked systems, the 2 mol % system was found to be most suitable to support catalytic activity. When a long flexible hydrophilic poly(ethylene glycol) crosslink, introduced between the polystyrene (PS) backbone and functional groups was used for immobilization, the extent of coupling and enzyme activity increased. Depending on the nature of the support, the catalytic activity of the system varied. The hydrophilic CLPSER support was most efficient for immobilization compared to the other PS‐based supports. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 8–19, 2005     

A study on polyurethane/acrylate crosslinked gel polymer electrolytes

2,4‐Toluene diisocyanate, poly(propylene glycol), poly(ethylene glycol) (PEG) and 2‐hydroxyethyl methacrylate were used to synthesize PEG–UA (urethane acrylate) monomer. The crosslinked polymer and gel polymer electrolytes were prepared in dioxane by free radical polymerization. The swelling behaviour, thermal degradation properties, morphology and ionic conductivity of the gel polymer electrolytes were investigated. With decrease in the proportion of dioxane used, the synthesized polymer's network density increased, its affinity with a solution of 1 M LiClO₄ in propylene carbonate (PC) decreased, and more microgel which diffused in the network. At the same time, the conductivity increased and reached 4 × 10^?4 S cm^?1 at 25 °C. Copyright © 2003 Society of Chemical Industry     

Characteristics of water-absorbent polymer emulsions

Water-in-Oil (W/O) and Oil-in-Water (O/W) type water absorbent polymer emulsions were studied using two different polymerization methods. W/O type water absorbent polymer emulsions were prepared by the inverse emulsion polymerization of ammonium acrylate (AA), the quaternized salt of dimethyl-aminoethyl methacrylate (DMQ) and acrylamide (AM) with N,N-methylene-bisacrylamide (MBA) as a crosslinker. A pH sensitive water absorbent polymer emulsion was prepared by the conventional emulsion polymerization of diethyl-aminoethyl methacrylate (DEAEMA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinker. It was confirmed that the water absorption capacity of crosslinked polymers in inverse emulsion was controlled by crosslink density and dissociative charge density, and the crosslinked polyDEAEMA particles had a phase transition property of swelling and shrinking with pH. The dispersions of these water swollen crosslinked polymer particles exhibited an increase in viscosity and thixotropic fluidity.     

Stimuli‐responsive molecularly imprinted hybrid polymer gel as a potential system for controlled release

The purpose of this study is to develop a stimuli‐responsive hybrid polymer gel system with an improved mechanical stability as a controlled drug delivery carrier that can undergo phase transition by the stimulation of ethanol–water mixture. For this aim, trimethoxysilane terminated poly(propylene glycol) by coupling of 3‐isocyanatopropyl‐triethoxysilane with the hydroxyl end groups of poly(propylene glycol) through urethane bonds was synthesized. Hybrid polymer gels prepared in the presence of tryptophan (Trp), as a model of drug, were characterized and gelation time of polymer network was obtained by monitoring the fluorescence emission of Trp in pre‐gel solution. Swelling, solvent uptake and release kinetic of polymer gels were evaluated depending on time. The diffusional exponents (n) and diffusion constants (k) of each gel were calculated by using the swelling kinetic data. The effect of precursors as a monomer on Trp release profile was analyzed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42913.     

Preparation of thermally stable,low dielectric constant,pyridine‐based polyimide and related nanofoams

Reaction of 6‐chloronicotinoyl chloride with p‐phenylene diamine resulted in preparation of a dichloro diamide compound. Subsequently, chloro displacement of this compound with 4‐amino phenoxy groups led to production of a new pyridine‐based ether diamine named as N,N′‐(1,4‐phenylene)bis(6‐(4‐aminophenoxy) nicotinamide). Novel polyimide was prepared through polycondensation reaction of the diamine with hexafluoroisopropylidene diphthalic anhydride (6‐FDA) via two‐step imidization method. In addition, new nanoporous polyimide films were produced through graft copolymerization of polyimide as the continuous phase with a thermally labile poly (propylene glycol) oligomer as the labile phase. The grafted copolymers were synthesized using reaction of the diamine and 6‐FDA in the presence of poly (propylene glycol) 2‐bromoacetate as thermally labile constituent via a poly(amic acid) precursor process. The labile block was decomposed via thermal treatment to release inert molecules that diffused out of the matrix to leave pores with diameters between 30 and 60 nm. The structures and properties of polyimide and polyimide nanofoams were characterized by different techniques including ¹H‐NMR, FTIR, TGA, DMTA, SEM, TEM, dielectric constant, and tensile strength measurement. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Shape Memory and Physical Properties of Composites of Polyethylene Oxide/Poly(Propylene Glycol)-Block-Poly(Ethylene Glycol)-Block-Poly(Propylene Glycol)/2,4-Toluene Diisocyanate,Polypyrrole, and Modified MWCNT

Structural variation and its influence on morphology, mechanical, thermal, and electrical conductivity properties of polyethylene oxide/poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol)/2,4-toluene diisocyanate/polypyrrole (PEO/P(P-E-P)G/TDI/PPy) blends and nanocomposites with varying PPy content were reported. The chemical and fundamental linkages were confirmed by FTIR. SEM micrographs demonstrated homogeneous PEO/P(P-E-P)G/TDI/PPy blend formation and globular morphology for nanocomposites. The mechanical and DSC parameters were found to increase systematically with increasing PPy content in blend films. While for nanocomposites, better results were observed for 0.1% PPy content. Maximum electrical conductivity and good shape recovery of 94% was obtained for the nanocomposite with 1% PPy content.     

Crystal properties of stearate esters of racemic and L(+) propylene glycol

The 1-monostearate and the distearate of pro-pylene glycol were prepared with racemic propylene glycol and L ( + ) propylene glycol, and their crystal properties were compared. Racemic propylene glycol-l-monostearate shows four dif-ferent polymorphic modifications whereas opti-cally active propylene glycol-1-monostearate is monomorphic, with a melting point of 54.0C and a long spacing of 50.6A. Racemic propylene glycol distearate has an unstable Form II, which transforms irreversibly to Form I near 44C. Form I melts at 58.8C. The two forms have long spacings of 53.4A (Form II) and 43.4A (Form I). Optically active propylene glycol distearate exhibits three crystalline modifications: an un-stable Form II which transforms irreversibly to Form I near 37C, with Form I melting at 53.9C, and a third, stable form, termed Form III, melt-ing at 58.80. The long spacings of the three forms are 51.9A, 43.6A, and 46.9A respectively. Heats of transition for the various phase changes are given.     

Chitosan,itaconic acid and poly(vinyl alcohol) hybrid polymer networks of high degree of swelling and good mechanical strength

Chitosan is a biodegradable, non‐toxic, biocompatible polymer convenient for use in drug delivery. In this study, hybrid polymeric networks (HPNs) based on chitosan, itaconic acid and poly(vinyl alcohol) (PVA) were prepared and characterized. Chitosan was dissolved in itaconic acid in order to obtain ionic crosslinking with the dicarboxylic acid. In the second step, this chitosan/itaconic acid network was mixed with PVA and chemically crosslinked with glutaraldehyde. The chitosan/itaconic acid ratio was kept constant, while the concentrations of PVA and glutaraldehyde were varied. All samples were characterized using swelling studies, dynamic mechanical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction and scanning electron microscopy. The equilibrium degrees of swelling obtained for the HPNs were higher than most of the values reported for chitosan hydrogels obtained by dissolving chitosan in acetic acid or HCl aqueous solutions. This method of synthesis also resulted in hydrogels with better mechanical properties and thermal stability. By changing the PVA content and the degree of crosslinking, it is possible to finely tune the properties of the HPNs, which could make them suitable as potential matrices in controlled drug delivery. Copyright © 2010 Society of Chemical Industry     

Polyurethane acrylate/epoxy–amine acrylate hybrid polymer networks

New classes of hybrid polymer networks (HPNs), having variable polyurethane acrylate (PUA) and epoxy–amine acrylate (EAA) compositions, were prepared using initially miscible systems in methyl methacrylate (MMA). The initial systems were based on PUA prepolymer and EAA monomer solutions in MMA. HPNs were a result of epoxy–amine and radical polymerization competition. Phase separation occurred during the course of HPN formation. Mechanical dynamic analysis of the prepared HPNs showed good affinity between the PUA and PMMA phases and lower affinity between the EAA and PMMA phases. Mechanical property evolution and transmission electronic microscopy showed that, for all the composition ranges used in this study (PUA/EAA/PMMA 15/45/40–45/15/40 wt %), the PUA‐rich phase was the continuous phase. EAA‐rich phases, 20–50 nm, in the PUA‐rich matrix were obtained for HPNs containing up to 30 wt % EAA. For higher EAA concentration (45 wt %), 2 μm EAA‐rich phases were obtained in the PUA‐rich matrix. A substructure was also observed in each phase. PUA/EAA copolymers were prepared and used successfully for the compatibilization of the different phases of the HPNs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2711–2717, 2000     

Synthesis of propylene glycol monoesters of docosahexaenoic acid and eicosapentaenoic acid by lipase-catalyzed esterification in organic solvents

Propylene glycol monoesters (PGM) of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are potentially health-beneficial water-in-oil emulsifiers useful in the food industry. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. The products were analyzed by gas chromatography. The immobilizedMucor miehei lipase was found to be the best enzyme for the synthesis of both propylene glycol monoesters of EPA and DHA among nine lipases tested. The anhydrous enzyme and hydrophobic organic solvents were favored for the production of both monoesters. The yields of monoesters were also affected by temperature, pH memory, fatty acid/propylene glycol ratio, and reaction time. The yields of PGMDHA and PGMEPA with 50 mM fatty acid and 225 mM propylene glycol as substrates in 1 mL solvent mixture (hexane/t-butyl alcohol=9:1), catalyzed by Lipozyme IM-20 (50 mg) at 40°C for 24 h, were 47 and 49 mM, respectively. The enzyme still retained over 60% of its original activity after 10 d of batch-type operation (1 d per cycle) at 40°C for the synthesis of both PGMDHA and PGMEPA.     

Production of propylene glycol fatty acid monoesters by lipase-catalyzed reactions in organic solvents

Fatty acid monoesters of propylene glycol (1,2-propanediol) are good water-in-oil emulsifiers. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. APseudomonas lipase was added to reaction mixtures containing propylene glycol and various acyl donors (fatty acids, fatty acid ethyl esters, fatty acid anhydrides and triglycerides) in organic solvents, and the mixtures were shaken at 30°C. The products were analyzed by gas chromatography. The yield of monoesters was affected by the acyl donors, organic solvents, temperature, water content, pH memory and reaction time. The anhydrous (lyophilized) enzyme and fatty acid anhydrides were best for monoester production. The optimum pH ranges were 4–5 and 8–10. The yields of propylene glycol monolaurate, monomyristate, monopalmitate, monostearate and monooleate with 50 mM fatty acid anhydrides as acyl donors were 97.2, 79.6, 83.7, 89.7 and 93.4 mM, respectively; those with 50 mM fatty acids as acyl donors were 37.3, 28.7, 28.7, 35.3 and 36.2 mM, respectively. The yields of propylene glycol monopalmitate, monostearate and monooleate with 50 mM triglycerides as acyl donors were 87.4, 65.1 and 83.2 mM, respectively.     

Synthesis and electrospun fiber mats of low Tg poly(propylene fumerate‐co‐propylene maleate)

Many publications have examined the biodegradable polymer poly(propylene fumate) (PPF) for use in tissue engineering applications. We have examined a similar crosslinkable polymer system, poly(propylene fumerate)‐co‐(propylene maleate) (PPFcPM), derived from maleic anhydride (MA) and 1,2‐propylene diol (PD). This copolymer system uses a less expensive monomer as well as leads to varied ratios of fumerate to maleate groups, allowing tuning of the crosslinked polymer properties such as degradation rate. Two different reaction conditions were used to synthesize the copolymer from MA and PD. In the first case (Method A), toluene was used as a solvent to azeotropically (85°C) remove water to drive the acid catalyzed esterification reaction. In the second case (Method B), the initial ring opening reaction was conducted, followed by addition of catalyst and removal of water to produce polymer of higher molecular weight. Both polymer systems had glass transition temperatures (T_g) below room temperature. The low T_g PPFcPM was dissolved in chloroform along with the photoinitiator phenylbis(2,4,6‐trimethylbenzoyl)‐phosphine oxide (BAPO) and electrospun. The polymer fibers were crosslinked soon after they formed to produce noncalendaring 3D porous scaffolds. Control experiments without the BAPO photoinitiator did not produce fiber mats. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

One-Step Synthesis of W/O and O/W Emulsifiers in the Presence of Surface Active Agents

The main goal of this study was to describe the method of the synthesis of the dodecyl-, tetradecyl-, hexadecyl- and octadecyl-propylene glycol emulsifiers in the presence of selected anionic and nonionic surfactants. Acyl propylene glycol emulsifiers were produced by esterification of propane–1,2-diol (propylene glycol, PG) with C_12:0–C_18:0 fatty acids in the presence of anionic sodium dodecyl sulfate (SDS) and nonionic-poly(ethylene glycol) monolaurate (PEGML). The presence of SDS and PEGML in the reaction system caused microemulsion formation. Depending on the structure and amount of the surfactant in the system reactions proceeded at different rates and with different efficiency levels. The esterification of propylene glycol carried out under applied conditions causes products with the desired contents of propylene glycol monoesters (MAPG) to be obtained in a one-step reaction. Knowledge of the reaction kinetics creates the possibility to program the composition and properties of the synthesized emulsifiers. The interaction of nonionic, lipophilic MAPG with anionic, hydrophilic SDS or nonionic, hydrophilic PEGML influences the hydrophile–lipophile balance (HLB) values of the products which may be used to stabilize water-in-oil (W/O) and oil-in-water (O/W) emulsions. Use of the synthesized compounds allows stable emulsions to be prepared which include the following vegetable fats in the oil phase: mango oil, palm oil, shorea butter and hydrogenated soybean oil.