Biodegradability of Poly(ethylene terephthalate) Copolymers with Poly(ethylene glycol)s and Poly(tetramethylene glycol)

✍ Scribed by Nagata, Minoru; Kiyotsukuri, Tsuyoshi; Minami, Susumu; Tsutsumi, Naoto; Sakai, Wataru

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 400 KB
• Volume: 39
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199602)39:2<83::aid-pi475>3.0.co;2-c

✦ Synopsis

Poly(ethy1ene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10- 40 mol% (in feed) of poly(ethy1ene glycol) (E) and poly(tetramethy1ene glycol) (B), with molecular weight (MW) of E and B 200-7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T,), cold crystallization and glass transition (T,) decreased with the copolymerization. T, depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. Tg was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for El000 series films than BlOOO series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.

K e y words: poly(ethy1ene terephthalate) copolymer, poly(ethy1ene glycol), poly(tetramethy1ene glycol), water absorption, biodegradability, in-vitro degradation, lipase, alkaline hydrolysis.