Blends of cellulose and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) prepared from the ionic liquid 1-butyl-3-methylimidazolium chloride

We report blends of cellulose and a microorganism-synthesized biopolymer, namely poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer prepared from an ionic liquid solvent, 1-butyl-3-methylimidazolium chloride. The ionic liquid was completely recycled with high yield and purity after the processing. The blends can be processed into different solid material forms such as films, noodle-like fibers and bulk blocks. These blends show phase-separated structure. The PHBV domains of 6-8 mu m, as analyzed with SEM and FTIR imaging, are distributed in a cellulose matrix at high concentrations of cellulose while the blends with high PHBV concentrations exhibit multiphase morphologies, including beadlike PHBV microdomains in the range of 300-400 nm. The dispersion of PHBV in cellulose leads to significant improvement in hydrophobicity due to its beadlike structure. Cellulose is a very brittle polymer and intractable to process. The addition of PHBV reduces the Young's modulus but increases the elongation at break, considerably plasticizing cellulose. (C) 2011 Elsevier Ltd. All rights reserved.