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 μm, 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.