Effects of Molecular Weight of Poly(ethylene glycol) on the Thermal Properties and the Alkaline Hydrolysis of Copolyesters

Abstract: Copolyesters containing sodium sulfonate group and poly(ethylene glycol) (PEG) were synthesized with var-ious molecular weight of PEG. The selected molecular weights of PEG were 1000, 2000, 4000, 6000, and 16000. Thethermal properties and the crystallization behaviors of the copolyesters were investigated by using differential scanningcalorimeter (DSC). Alkaline hydrolysis of the copolyesters was studied as a function of the treatment time. The meltingtemperatures and the heats of fusion of the copolyesters increased with an increase in the PEG molecular weight, whilethe weight reduction rate of copolyesters in an alkaline solution decreased with an increase in the PEG molecular weight.At the same PEG content in copolyesters, hard segment length increases with the PEG molecular weight, which wasthought to be the most important factor that determines the thermal properties and the alkaline hydrolysis behavior. Keywords: copolyesters, molecular weight of PEG, hard segment length, thermal properties, hydrolysis in alkaline solution