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]}

Abstract

Copolyesters of 8-(3-hydroxyphenyl)octanoic acid (HPOA), a monomer with kink and exible segment derived from cardanol, and 4-hydroxybenzoic acid (HBA) or its brominated derivative, 3-bromo-4-hydroxybenzoic acid (BrHBA), were synthesized by acidolysis melt polycondensation of the in situ generated acetoxyderivative in the presence of magnesium acetate as catalyst by a one-pot method and characterized. The formation of the copolyester was con®rmed by elemental analysis, FTIR and 1 H NMR spectroscopy. These polymers were highly insoluble in most solvents except highly polar solvents, such as tri¯uoroacetic acid. The inherent viscosities of the soluble polymers were in the range of 0.8±1.1 dlg À1 . The thermal and phase behaviour of the copolyesters were studied by DSC and polarized light microscopy. Poly{(4-oxybenzoate)-co-[8-(3-oxyphenyl)octanoate]} with 50 mole% of HPOA showed a birefringent melt with opalescence and a worm-like texture of a nematic phase. The effect of bromine substitution in the analogue poly{(3-bromo-4-oxybenzoate)-co-[8-(3-oxyphenyl)octanoate]} was evident when it showed a lower transition with minimum 45% Br-HBA at 225°C showing enhanced melt processability. These copolymers, with hydrolytically degradable aliphatic carbonyl group and better crystallinity compared to poly(hydroxyalkanoate)s, are interesting in possible biomedical applications.

Semiflexible random thermotropic copolymers from 8‐(3‐hydroxy phenyl) octanoic acid and 3‐chloro‐4‐hydroxy benzoic acid/3,5‐dibromo‐4‐hydroxy benzoic acid

“…Furthermore, substitution in the 3‐position of 4‐HBA by bromine enhanced this melting range, and the results are discussed in this article. The copolymer poly[3‐bromo‐1,4‐oxybenzoate‐ co ‐8‐(3‐oxyphenyl) octanoate was found to have better thermal stability and at the same time yielded a lower transition temperature than that of the copolyester without the bromine substitution 24. These results prompted us to study the copolymers of HPOA with other substituted monomers such as 3‐chloro‐4‐hydroxy benzoic acid (CHBA) and 3,5‐dibromo‐4‐hydroxy benzoic acid (DBHBA).…”

Challenges for Natural Monomers and Polymers: Novel Design Strategies and Engineering to Develop Advanced Polymers

“…7. A new monomer 8-hydrooxyphenyl octanoic acid was prepared by phase-transfer-catalyzed permanganate oxidation of cardanol a series homo-polymers and LCPs were prepared and characterized including LCP blends [192][193][194][195][196][197][198][199][200][201][202]. The polymers were shown to hydrolytically degradable.…”