Fabrication of Honeycomb-Structured Porous Films From Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) via the Breath Figures Method

Formation of porous films from poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) using the breath figures (BF) method was investigated by evaporating solutions in chloroform in humid air and examining film structure using optical and scanning electron microscopy (SEM). BF films were successfully fabricated from PHB (M-w = 486,000 g/mol) and displayed hexagonal arrays of pores, which varied in diameter (D = 72 mu m) with solution concentrations (0.5-2.00%). SEM of fractured films also showed subsurface closed nano-pores (D = 500-700 nm). BF films cast from PHBV (5% HV) formed arrays with smaller pores and apparent surface defects. Differential scanning calorimetry showed that porous PHB and PHBV films produced using the BF method were more crystalline than nonporous solvent cast films of PHB and PHBV. POLYM. ENG. SCI., 52:920-926, 2011. (C) 2011 Society of Plastics Engineers