Carbon nanotube mediated miscibility of polyhydroxyalkanoate blends and chemical imaging using deuterium-labelled poly(3-hydroxyoctanoate)

Biopolymers have potential as scaffolds supporting regrowth of damaged tissues, however their material properties may limit the range of applications. Blending polymers with different thermomechanical properties has been demonstrated to extend the range of possible applications for polyhydroxyalkanoate (PHA) polymers, while the addition of nanoparticles can be used to modulate miscibility which influences strength and flexibility of the blend. Here we report on the blending of Poly(3-hydroxybutyrate) and Poly(3-hydroxyoctanoate) which possess different thermomechanical properties, and the effect of single wall carbon nanotubes (SWCNT) on their miscibility, electrical conductivity and thermomechanical performance. The apparent perturbation of phase boundaries in nanocomposite films observed by Scanning Electron Microscopy (SEM) was complemented by chemical mapping of film cross sections containing a deuterium -labelled poly(3-hydroxyoctanoate) phase in the blend using Infrared Microspectroscopy (IRM), suggesting increased miscibility due to nanoparticle addition. The electrical percolation threshold in nanocomposite films was observed between 0.5 and 1 wt% SWCNT, where the surface resistivity was reduced by eight orders of magnitude compared to the insulating polymer blend. Addition of SWCNT did not impact significantly on mechanical properties of films containing up to 2.5 wt % SWCNT. A solvent cast bionanocomposite film containing optimally 1 wt% SWCNT yielded a material with improved electrical conductivity compared to the SWCNT-free blend and which supported growth of Olfactory Ensheathing Cells, providing a basis for developing biopolymer scaffolds capable of conducting electrical stimulation.