PCO-LLDPE thermoresponsive shape memory blends. Towards a new generation of breathable and waterproof smart membranes

Abstract Different polycyclooctene (PCO) and linear low-density polyethylene (LLDPE) blends were crosslinked with 2 wt% of dicumyl peroxide (DCP) in order to obtain thermoresponsive shape memory materials with transition temperatures close to bodýs external temperature. These polymeric blends allow tailoring properties by the synergic combination of shape-memory capability of PCO and effective mechanical and processing performance of polyethylene. Thermal stability of these materials was characterised by thermogravimetric analysis (TGA), whereas mechanical performance was measured by dynamic mechanical analysis (DMA) and tensile tests. Besides, thermal properties were measured by differential scanning calorimetry (DSC), where the melting temperature of crystalline PCO phase around 40–50 °C were observed. Considering this shape memory triggering temperature, the shape memory capabilities of the samples were studied by thermo-mechanical analysis (TMA), and outstanding shape recovery ratios were obtained. Finally, water contact angle (WCA) and water vapour transmission rate (WVTR) were measured above and below that transition temperature to assess moisture permeability changes. In this case, observed increase by an order of magnitude in vapour permeability with temperature offers promising opportunities in developing thermo-active membranes for textile applications with these PCO-LLDPE blends.