Poly(vinyl alcohol) particle-reinforced elastomer composites with water-active shape-memory effects

Polymer composites with excellent water-active shape-memory effects (SMEs) were successfully prepared using polyvinyl alcohol (PVA) submicron particles as the SME-activating phase and thermoplastic polyurethane (TPU) as the resilient source and matrix. The incorporation of high-modulus, hydrophilic PVA particles (with a size of 80-200 nm) improved the Young's modulus and water uptake of elastomeric and hydrophobic TPU significantly, which leads to large changes of the modulus upon exposure to water. Water acted as a plasticizer of PVA phase, decreasing its modulus. Such modulus changes were reversible and dependent on the content of PVA particles, which can be up to 16 times. As a result, the shape-memory performance of the composite was also dependent on the content of PVA particles. The PVA particle-reinforced TPU composite containing 15 vol.% PVA particles exhibited the best SMEs among the composites investigated, with the shape fixing and shape recovery ratios being 97% and 97%, respectively. (C) 2014 Elsevier Ltd. All rights reserved.