PVA–Polystyrene-Based Polymer Films with Water-Induced\nShape-Memory Effect

Abstract

In\nthis work, a series of novel water-induced shape-memory composite\nfilms are prepared on the basis of poly­(vinyl alcohol)-polystyrene\n(PVA–PS_<i>X</i>) through one pot in situ\npolymerization method. The neat PVA film is modified to PVA–PS_<i>X</i> film by loading calibrated amount of styrene,\nand the resulted film exhibits high mechanical strength (tensile strength\n∼40 MPa, tensile strain ∼315%, Young’s modulus\n∼0.25 MPa and toughness ∼5 MJ/m³). More importantly,\nwater-induced shape-memory behavior is observed for the PVA–PS_<i>X</i> composite films and among various proportions,\nPVA–PS₃ film (3 v/v% of styrene content) shows the\nfastest shape recovery rate (160 s). The relative low value of storage\nmodulus and glass transition temperature of the PVA–PS₃ films is attributed to water-induced shape recovery. The\ndesirable and multifaceted properties of the PVA–PS_<i>X</i> composite film, such as optimum transparency, improved\nwater resistance, enhanced shape recovery, diminished UV-light transmission,\nand effectual antimicrobial activity, propound that the composite\nfilm is a suitable candidate for preparing packaging materials in\nfood and cosmetic industries.