| Abstract: | The thermal properties and biodegradability of block copolyesterethers based on copolysuccinic anhydride (SA)/ethylene oxide (EO)] (polymer composition range SA/EO 42/58–49/51 mol %), synthesized by ring-opening copolymerization and poly(ethylene glycol) (PEG) or poly(propylene glycol) (PPG), were studied. The block copolyesterethers synthesized from higher than 7000 molecular weight (Mn) or high SA content copoly(SA/EO), SA/EO = 48/52 or 49/51, and PEG showed melting points and fusion heats (ΔH) similar to those of the prepolymers without leading to a microphase-separation structure. Enzymatic degradability of the block copolyesterethers synthesized from biodegradable copoly(SA/EO) with a low SA content (SA/EO = 42/58 mol %) and PEG was significantly smaller compared to that of the chain-extended copoly(SA/EO) used as a prepolymer. On the other hand, the block copolymers synthesized by an equimolar amount of copoly(SA/EO) and PPG showed evidence of a microphase-separation structure. An increase in propylene glycol (PG) content interfered with the formation of a microphase-separation structure. However, the block copolyesterethers including nonbiodegradable copoly(SA/EO), with a high SA content (SA/EO = 49/51 mol %), and PPG were found to be enzymatically degradable. In the biodegradation testing with standard activated sludge, the block copolyesterethers were degraded by microorganisms in activated sludge. The relationship between polymer composition and the biodegradation rate by activated sludge shows a similar trend to that of enzymatic hydrolysis. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2095–2106, 1998 |
