Enzymatic biodegradation of synthetic atactic poly(R,S-3-hydroxybutyrate) enhanced by an amorphous nonbiodegradable polymer

The phase structure and biodegradability were investigated for blends of chemosynthetic atactic poly(R,S-3 -hydroxybutyrate), a-P(R,S-3HB), with poly(methyl methacrylate), PMMA. A series of blends with different composition was prepared from casting the chloroform solution on a Teflon dish. The thermal analysis indicated that amorphous a-P(R,S-3HB)/PMMA blends possess sophisticated phase behavior and are partially miscible at PMMA contents ranging from 10 to 50 wt.%. a-P(R,S-3HB) was enriched in the 'air' surface while PMMA was enriched in the 'bottom' surface of the film as suggested by the ATR FTIR spectra of the blend with PMMA content of 40 wt.%. The depolymerase of natural poly((R)-3-hydroxybutyrate) purified from Alcaligenes faecalis T1 did not degrade chemosynthesized a-P(R,S-3HB) at all in the pure state, but it degraded a-P(R,S-3HB) in some a-P(R,S-3HB)I PMMA blends. The results suggested that enzymatic degradation of a-P(R,S-3HB) can be enhanced by blending with an amorphous nonbiodegradable polymer. (C) 2001 Elsevier Science Ltd. All rights reserved.