Fabrication of SrTiO3−Tween80 reinforced biological poly-3-hydroxyalkanoate composite film and its proton permeability

Flexile composite film of Poly-3-hydroxyalkanoate−Perovskite−Tween 80 (PHA-PV-T80) as a green membrane film was prepared. Pristine medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA), produced through bacterial fermentation, was blended with different concentrations of perovskite (PV) and Tween 80 (T80) ranging from 0.01 to 0.0025 % ( w/v) and 1.5 – 4.5 % ( w/v), respectively, to fabricate the composite films. Ultrasound irradiation was applied to aid homogenous dispersion of blend solution prior to film casting. The composite film exhibited improved physical properties compared to the neat mcl-PHA film, which is more susceptible to ripping upon peeling. Thorough distribution of perovskite, facilitated by T80, were responsible for promoting increased side-chain crystallization, resulting in the formation of extensive rigid regions within the PHA matrix, which significantly improved proton permeability of the composite film. PHA composites showed higher proton flux (>3.5 × 10−4 mol.min−1.cm−2) compared to neat PHA (1.03 × 10−4 mol.min−1.cm−2) and commercial Nafion (1.22 × 10−4 mol.min−1.cm−2). The relationship between physicochemical attributes and proton flux characteristics of the composite films were discussed with regards to their potential application as proton exchange membrane.