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.