Biodegradation of poly(3-methoxy-4-hydroxy styrene)

Poly(3-methoxy-4-hydroxy styrene) (MHS) was prepared as a biodegradable polymer; it offers a simplified model of naturally biodegradable polymers related to softwood lignin, having pendant guaiacyl groups. This polymer was decomposed by microorganisms in soil, and four intermediates were identified in the degradation pathway. Judging from the identified intermediates, vanillic acid seems to be the first biodegradation product of polyMHS in the pathway. The ring cleavage of vanillic acid gives rise to monomethyl ester of β-carboxymuconic acid, discovered as an intermediate in the degradation pathway. Monomethyl ester of β-carboxymuconic acid, which was isolated and characterized, is decomposed to maleic and oxalic acids by microorganisms which are essential for utilization of guaiacyl group. Elucidation of the degradation pathway of polyMHS revealed that the step reactions responsible for the conversion of this compound to maleic and oxalic acids are somewhat similar to the step reactions responsible for the degradation of lignin by microorganisms.     

Catalytic autoxidation of 9(10)-formylstearic acid

A procedure has been developed for the preparation of carboxystearic acid by catalytic autoxidation of hydroformylated oleic acid. This autoxidation is catalyzed effectively with Ca, Cu, Co, Fe, Mn and Ce naphthenates in either acetone or glacial acetic acid at 20 C. With the exception of Ca, all these catalysts produce from 2 to 10% keto- and hydroxystearic acids as by products. Yields of up to 95% 9(10)-carboxystearic acid are obtained by autoxidation for 24 hr with Ca naphthenate (0.5% Ca based on formylstearate). This autoxidation period was shortened to 7 hr by using a binary catalyst (0.5% Ca and 0.05% Mn), which affords a minimum of side products.     

Effects of alkali halides on the thermal decompositions of poly(methyl methacrylate) and poly(2-hydroxy ethyl methacrylate)

The effects of alkali halides on the nonoxidative thermal degradations of poly(methyl methacrylate) and poly(2-hydroxy ethyl methacrylate) are described. The magnitudes of the effects of various alkali halides on polymer thermal degradation were found to depend on the salt and the polymer. Mass spectrometric analysis of volatiles evolved during polymer degradation detected alkyl halides formed by reactions between the salts and polymers. Compared to poly(methyl methacrylate), more alkyl halide was evolved from samples containing alkali halides and poly(2-hydroxy ethyl methacrylate). To varying degrees, salts also catalyzed ester decomposition reactions for this polymer. Infrared spectroscopic analysis results showed that carboxylate salts, carbonate, and carbon monoxide were formed by heating polymer/salt mixtures. © 1996 John Wiley & Sons, Inc.     

Surface-catalyzed growth of poly(2-methoxyaniline) on gold

We report on catalytic growth of poly(2-methoxyaniline) on gold surface by in situ polymerization. The mechanism of catalysis and products of monomer oxidation are elucidated on the basis of complementary investigations including Raman and UV-Vis spectroscopy, surface plasmon resonance, electrospray ionization mass spectrometry, gel permeation chromatography as well as electrochemical and microscopic techniques.It was shown that chemical oxidation of 2-methoxyaniline in acidic medium results in formation of a linear trimer which is the only stable product yielded in the bulk of the solution. However, introduction of a gold substrate into the reaction mixture induces polymerization of monomers/oligomers and formation of a thin polymeric film on the surface. This catalytic activity of gold is associated with adsorption of trimeric species onto the metal. The oligomers, being in fully oxidized (quinoid) form in the solution, are reduced to radical cations after adsorption onto the gold substrate. Since the radical cations are significantly more reactive than fully oxidized species, the polymerization proceeds on the surface, while it is inhibited in the solution.     

Preparation of gold nanoparticles on poly(methyl methacrylate) nanospheres with surface-grafted poly(allylamine)

A facile method for in situ anchoring of gold nanoparticles onto the surface of polymer nanospheres was successfully developed in this study. As polymer nanospheres, amphiphilic poly(methyl methacrylate) (PMMA)/poly(allylamine) (PAA) nanospheres were prepared by graft copolymerization of methyl methacrylate from PAA. The gold nanoparticles anchored were spherically symmetric and the average sizes were ∼12 nm for all samples. It was found that surface-grafted PAA effectively anchored and stabilized gold nanoparticles for a long period of time.     

The Mannich bases in polymer synthesis: 3. Reduction of poly(β-aminoketone)s to poly(γ-aminoalcohol)s and their N-alkylation to poly(γ-hydroxy quaternary ammonium salt)s

Several poly(β-aminoketone)s, obtained by polyconensation of bis Mannich bases with bis (secondaryamine)s, have been quantitatively reduced to poly(γ-aminoalcohol)s. The stereochemistry of these polymers, as well as that of the reduction products of the parent bis Mannich bases has been investigated. By N-alkylation of the same polymers, poly(γ-hydroxy quaternary ammonium salt)s have been also prepared.     

Charge-carrier relaxation dynamics of poly(3-hexylthiophene)-coated gold hybrid nanoparticles

Poly(3-hexylthiophene)-coated gold (Au@P3HT) hybrid nanoparticles have been prepared via a “grafting-to” approach, and compared with pristine P3HT to investigate the dynamics of exciton relaxation using time-resolved transient-absorption and fluorescence spectroscopy. In efforts to facilitate the efficient dissociation of photo-generated excitons, we have incorporated gold nanoparticles having surface-plasmon resonances into thiol-terminated P3HT to fabricate Au@P3HT nanocomposites. The first-excited singlet state of Au@P3HT decays faster than that of pristine P3HT due to interactions with surface-plasmon resonances; excitons undergo dissociation via energy transfer from P3HT to the surface-plasmon state of a gold nanoparticle in Au@P3HT nanocomposites. The lowest triplet state of P3HT is also less populated due to the energy transfer while its lifetime is slightly reduced by the presence of gold nanoparticles. Thus, it is suggested that our incorporation of gold nanoparticles into P3HT reduces the recombination of geminate excitons and, thereby, increases the probability of exciton dissociation.     

The effect of lanthanum oxide (La2O3) on the structure and crystallization of poly(vinylidene fluoride)

Rare earth polymers, due to their excellent luminescence, fluorescence, laser protective, optical and magnetic properties, have attracted much research attention in recent years. However, little attention has been paid to the effect of rare earths on the structure and crystallization of polymers, which is of important significance in the development of functional polymers. X‐ray diffraction and differential scanning calorimetry were used to investigate the structure and crystallization behavior of a poly(vinylidene fluoride) (PVDF)/lanthanum oxide (La₂O₃) composite. The results showed that the degree of perfection, crystal size, crystallization rate and isothermal crystallization activation energy of PVDF in the composite decreased, compared with pure PVDF. The spherulite nucleation and growth for PVDF and PVDF composite were analyzed in detail using the Lauritzen‐Hoffman equation. The modified Avrami equation and the Mo equation were used to study the non‐isothermal crystallization kinetics. The addition of La₂O₃ did not change the crystal structure and nucleation process for PVDF, but it decreased markedly the crystal growth rate and led to the formation of unstable crystals. This was attributed to the fact that too much La₂O₃ prevented PVDF molecular chains from moving and arranging in an orderly manner into crystals. Copyright © 2010 Society of Chemical Industry     

The effect of alumina particulate morphology on the properties of reinforced poly(propylene) and poly(ethylene-co-vinyl acetate) composites

The effect of alumina particulates on a thermoplastic matrix is investigated, in particular the effect altering the alumina particle size and morphology has on the mechanical properties. Different grades of alumina are used and two thermoplastic matrices; namely poly(propylene) and poly(ethylene-co-vinyl acetate). Investigations showed that optimum properties were achieved with the alumina of smallest particle size and lowest aspect ratio. Preliminary work has also been performed on the use of silane coupling agents and they have proved effective in increasing the tensile properties of the composites.     

The effect of poly(ethylene glycol) as plasticizer in blends of poly(lactic acid) and poly(butylene succinate)

The effect of polyethylene glycol (PEG) on the mechanical and thermal properties of poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) blends was examined. Overall, it was found that PEG acted as an effective plasticizer for the PLA phase in these microphase‐separated blends, increasing the elongation at break in all blends and decreasing the T_g of the PLA phase. Significant effects on other properties were also observed. The tensile strength and Young's modulus both decreased with increasing PEG content in the blends. In contrast, the elongation at break increased with the addition of PEG, suggesting that PEG acted as a plasticizer in the polymer blends. Scanning electron microscope images showed that the fracture mode of PLA changed from brittle to ductile with the addition of PEG in the polymer blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43044.     

Thermal analysis of FeCl3-doped poly(3-butylthiophene) and poly(3-dodecylthiophene)

Summary For neutral and FeCl₃-doped poly(3-butylthiophene) (P3BT) and poly(3-dodecylthiophene) (P3DDT), conductivity measurement and thermal analysis are performed. Before doping, the glass transition temperatures (T_g) of the P3BT and P3DDT are 75.4°C and 5.6°C respectively. No melting transition of an ordered phase for P3BT is observed. But for P3DDT, the melting temperatures of ordered side chains and main chains are 56.1°C and 116.3°C respectively. Upon doping, the T_g 's shift upward to 150.5°C and 51.2°C for P3BT and P3DDT respectively and the two melting peaks of the ordered phases of P3DDT disappear. The dopant anions decompose in the range of about 150 to 230°C. The conductivities increase with increasing temperature and reach maxima at 135°C and 28°C and drop sharply in the range of 160–200°C and 130–170°C for P3BT and P3DDT respectively. This indicates that the thermal motion of the main chains would lead to a drop of conductivity due to thermal undoping, while the dopant decomposition would lead to a rapid loss of conductivity and an occurrence of crosslinking reaction.     

NMR studies of poly(2-hydroxy ethyl methacrylate-co-2-vinyl pyridine)

Copolymers of 2-hydroxy ethyl methacrylate-2-vinyl pyridine (H/V) of different composition were synthesized by free radical bulk polymerization using azobisisobutyronitrile (AIBN) as an initiator under nitrogen atmosphere. The copolymer compositions were calculated from ¹H NMR spectra. The reactivity ratios for H/V copolymers obtained from a linear Kelen-Tudos method (KT) and nonlinear error-in-variables method (EVM) are r_H = 0.50 ± 0.10, r_V = 1.04 ± 0.08 and r_H = 0.55, r_V = 1.06 respectively. The complete spectral assignment of methine, methylene, methyl, carbonyl, and aromatic carbon regions in term of compositional and configurational sequences of H/V copolymers were done with the help of ¹³C{¹H} NMR, distortionless enhancement by polarization transfer (DEPT), two-dimensional heteronuclear single quantum coherence (HSQC) along with total correlated spectroscopy (TOCSY). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Functional gold nanorod particles on conducting polymer poly(3-octylthiophene) as non-enzymatic glucose sensor

The immobilization of surface-functionalized self-assembled monolayer (SAM) gold nanoparticles onto poly(3-octylthiophene) (POT) was achieved by the cooperation of hydrophobic forces. SAMs were prepared by 11-mercaptoundecanoicacid (MUA), 4-mercaptophenyl boronic acid (MPB), and 1-decanethiol (DT) hydrophobic substrates. Nanoparticles-SAM-POT system was characterized by cyclic voltammetry, SEM, EDAX and contact angle measurements. SAMs (MUA) is closely packed providing effective blocking of the underlying platinum electrode and preventing a ferrocyanide molecule from penetrating. However, potential scanning was applied at SAMs (MUA) modified electrode on which electron penetrating holes or defects were occured. Since SAMs (MPB) is poorly packed according to SAMs (MUA), ferrocyanide molecules could penetrate to SAMs (MPB) modified electrode surface. POT-Au-SAM (MPB) electrode was used for glucose determination as potentiometric non-enzymatic glucose sensor. The analytical performance was evaluated and linear calibration graphs were obtained in the concentration range of 5-30 mM glucose including the level of human blood glucose.     

Segregation morphology of poly(3-hydroxybutyrate)/poly(vinyl acetate) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate)/poly(vinyl acetate) blends as studied via small angle X-ray scattering

Segregation morphology of poly(3-hydroxybutyrate) (PHB)/poly(vinyl acetate) (PVAc) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate) (P(HB-co-10% HV)/PVAc blends crystallized at 70 °C have been investigated by means of small angle X-ray scattering (SAXS). Morphological parameters including the crystal thickness (l_c) and the amorphous layer thickness (l_a) were deduced from the one-dimensional correlation function (γ(z)). Blending with PVAc thickened the PHB crystals but not the P(HB-co-10% HV) crystals. On the basis of the composition variation of l_a, and the volume fraction of lamellar stacks (?_s) revealed that PHB/PVAc blends created the interlamellar segregation morphology when the weight fraction of PVAc (w_PVAc)≤0.2 and the interlamellar and interfibrillar segregation coexisted when w_PVAc>0.2, while P(HB-co-10% HV)/PVAc blends yielded the interfibrillar segregation morphology at all blend compositions. For both PHB/PVAc and P(HB-co-10% HV)/PVAc blends, the distance of PVAc segregation was promoted by increasing PVAc composition and the distance of PVAc segregation in P(HB-co-10% HV)/PVAc blends was greater than in PHB/PVAc at a given PVAc composition. The crystal growth rate played a key role in controlling the segregation of PVAc.     

The effect of additives on the crystallization of poly (butylene terephthalate)

The effect of glass fibers and some fire retardant additives on the kinetics and mechanism of crystallization of poly(butylene terephthalate) (PBT) has been investigated. Shorter half times of crystallization and higher optimum crystallization temperatures of the filled samples are attributed to the nucleating ability of the additives. Based on the percent crystallinity determined, the efficiency of the different quenching media studied can be arranged in the order: ice water > 25°C water ? dry ice/ethanol > liquid nitrogen. The inefficient quenching of dry ice/ethanol arid liquid nitrogen media is attributed to their poor heat transfer. The T_g of these quenched samples is, however, independent of the percent crystallinity.     

The effect of curing on the crystallization of poly(phenylene sulfide)

Summary Poly(phenylene sulfide) (PPS) was cured in the melt and solid states under air and/or nitrogen environments. Crystallization behavior of such cured materials as a function of cure time at 320°C and 255°C was studied via differential scanning calorimetry. It was found, on general, that while short-time curing leads to an increase in crystallization rate, prolonged curing leads to a decrease in both crystallinity and crystallization rate. In contrast to the enhanced crystallization rate caused by curing in nitrogen at the melt state, no significant change of crystallization rate is observed while curing is done in the solid state (in nitrogen).     

The effect of amines on the dehydrochlorination of poly(vinyl chloride)

A study has been made of the effect of amines, particularly those used as catalysts in the preparation of polyurethane foams, on the dehydrochlorination of poly(vinyl chloride) (PVC). It has been shown that when PVC is heated at a temperature of 80°C in the presence of amines the levels of dehydrochlorination produced are considerably greater than those found if no amine is present. This has been attributed to a chemical dehydrochlorination reaction and could well have implications with respect to the physical and mechanical properties of the polymer for certain of its commercial applications.     

Protective effect of the phenyl group in γ-irradiated compatible blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile)

The sensitivity to radiation of mixtures of poly(methyl methacrylate) (PMMA) and polystyrene-co-acrylonitile) (SAN) was studied over the entire range of composition. Polystyrene-co-acrylonitrile, like polystyrene, is highly resistant to ionizing radiation, having a small G_x value for crosslinking (0.077) and an even smaller G_s value for main chain scission (0.055). In contrast, PMMA degrades readily under irradiation (with G_s = 1.2). In γ-irradiated blends, the behavior of each polymer is largely influenced by the presence of the other component. Gel formation in SAN is impeded by PMMA, as a result of a decrease in G_x, and a concomitant increase in the ratio G_s/G_x. Flexural strength measurements, along with molecular weight determinations by gel permeation chromatography, demonstrated that SAN had a marked protective effect on PMMA by decreasing G_s (chain scission). This protective effect was not observed in earlier experiments with PMMA–PS blends, in spite of its chemical similarity to the system PMMA–SAN. The difference in behavior between PMMA–PS and PMMA–SAN may be explained on the basis of polymer compatibility. PMMA and SAN form a compatible pair, whereas PMMA and PS are incompatible; thus the short range protective effect of the phenyl groups in PS is inhibited.