Polymer, Vol.104, 61-71, 2016
Fabrication and characterization of poly(3-hydroxybutyrate) gels using non-solvent-induced phase separation
Chloroform (CF) solutions of biodegradable poly(3-hydroxybutyrate) (PHB) formed organogels upon the addition of tetrahydrofuran (THF) as a non-solvent at room temperature. Conformational changes of PHB chains during gelation were monitored in situ by time-dependent infrared spectral (IR) measurements. Analysis of the IR spectra for different wavenumber regions (C-H, C=O, and C-O-C stretching vibration regions) showed that PHB chains underwent a molecular transition from a random coil to a helix indicating formation of a crystalline phase following a liquid-liquid phase separation during gelation. Applying solvent exchange and freeze-drying processes to the as-produced organogels allowed fabrication of nanofibrous PHB monoliths with high porosity (similar to 97%) and surface areas up to 72.1 +/- 0.6 m(2)/g. It was shown that by varying the solvent mixture composition (THF/CF ratio), the gelation kinetics, crystallization behavior, nanofibrous structure, pore character, surface area, and the mechanical properties of PHB aerogels, were effectively controlled. (C) 2016 Elsevier Ltd. All rights reserved.