Melt‐processable poly(oxyphenylalkanoate): Synthesis, properties, and in vitro degradation of poly(4‐oxyphenylacetate)

Abstract

The homopolyester of 4‐hydroxyphenylacetic acid (HPAA) was synthesized by one‐pot, slurry‐melt, and acidolysis melt polymerization techniques and was characterized by its inherent viscosity and IR and NMR spectra. Differential scanning calorimetry (DSC), polarizing light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) studies of the homopolymer were carried out for its thermal and phase behavior. The results indicated that the yield and molecular weight of the polymer depended on the method of preparation; moreover, the acidolysis melt polymerization of the pure acetoxy derivative of HPAA was the best method for the preparation of high molecular weight poly(4‐oxyphenylacetate) (polyHPAA) without side reactions. DSC and PLM studies also showed that the thermal and optical properties depended largely on the polymerization conditions and inherent viscosity values. PolyHPAA did not show a clear texture typical of liquid‐crystalline polymers, whereas after cooling from the melt, structures similar to spherulitic crystals were observed. WAXD patterns showed a crystalline nature. The in vitro degradability of the polymer was also studied via the water absorption in buffer solutions of pH 7 and 10 at 30 and 60 °C; this was followed by Fourier transform infrared, inherent viscosity, DSC, thermogravimetric analysis, WAXD, and scanning electron microscopy techniques. Unlike Vectra®, which showed no degradation, polyHPAA showed an increase in hydrolytic degradation from 5.0 and 6.0% at 30 °C to 12.5 and 15.0% at 60 °C after 350 h in buffer solutions of pH 7 and 10, respectively. The results indicated a possible biomedical prosthetic application of poly(oxyphenylalkanoate)s such as polyHPAA with better crystallinity coupled with degradability as a substitute for poly(hydroxyalkanoates). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2430–2443, 2001

Synthesis, characterization, and in vitro degradation of liquid‐crystalline terpolyesters of 4‐hydroxyphenylacetic acid/3‐(4‐hydroxyphenyl)propionic acid with terephthalic acid and 2,6‐naphthalene diol

“…Terpolymers of TA, HPAA or HPPA, and ND were prepared by a catalyzed acidolysis polycondensation of these monomers by a one‐step polymerization method. A special glass reactor was constructed to carry out the polymerization reaction 9. The glass reactor was charged with the requisite amount of the monomers and acetic anhydride in a slight excess and magnesium acetate as a transesterification catalyst.…”

Disulfide Bond Creates a Small Connecting Loop in Aminoxy Peptide Backbone

“…In the case of poor compatibility between the components, compatibilizers are also used to obtain polymer blends that reduce the interfacial energy, resulting in finer dispersion of blend components and enhanced mechanical properties to the blends. References are available where compatibilization of polymer blends was achieved using graft polymers,6, 7 in situ compatibilization,8–14 copolymerization reaction,15 interchange reaction,16 and similar techniques.…”

Copolyesters of hydroxyphenylalkanoic acids: synthesis and thermal properties of poly{(4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} and poly{(3‐bromo‐4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]}

“…In addition, copolymerization with monomers having aliphatic carbonyl groups will increase the hydrophilicity to impart hydrolytic degradability 15. 16 Our previous study has shown that copolymerization of 4‐hydroxybenzoic acid (HBA) with naturally occurring hydroxyphenylalkanoic acids like 4‐hydroxyphenylacetic acid or 3‐(4‐hydroxyphenyl)propionic acid gives hydrolytically degradable liquid‐crystalline polyesters with improved processability 17. 18 In this respect, 8‐(3‐hydroxyphenyl)octanoic acid (HPOA) is yet another monomer synthesized by phase‐transfer‐catalyzed oxidation of cardanol, a natural monomer 19.…”