Synthesis, physical properties and enzymatic degradation of poly (oxyethylene-b-butylene succinate) ionomers

A series of poly(oxyethylene-b-butylene succinate) (POBS) ionomers were synthesized by a two-step polycondensation of succinic acid and mixed monomers of sodium sulfonated polyethylene glycol (SPEG) and 1,4-butanediol. The composition and chemical structure of these segmented ionomers were determined by 1H NMR spectroscopy. To evaluate the potential uses of POBS copolymer in disposable applications, we investigated the crystallinity, dynamic mechanical properties and susceptibility to enzymatic hydrolysis. The crystallinity of POBS copolymer decreased considerably with increasing SPEG content because ionic interaction led to retardation of chain folding. Even so, POBS with 0.5 mol% SPEG showed the highest storage modulus among tested samples. This result is attributed to intermolecular interactions. Enzymatic hydrolysis of POBS copolymer occurs more rapidly than homo poly(butylene succinate) and was drastically accelerated with increasing ionic contents. This is attributed to the presence of the ionic group, which not only reduced the crystallinity but also improved hydrophilicity on the POBS surface.