Triple shape-memory effect by silanized polyurethane/silane-functionalized graphene oxide nanocomposites bilayer

Graphene oxide (GO) was chemically modified with 3-aminopropyltriethoxysilane (APTES) (f-GO) and incorporated into silanized polyurethanes of two different molecular weights and chemical compositions by sol-gel reactions, and the effects were studied in terms of mechanical, dynamic mechanical, and dual and triple shape-memory polymers (DSMP and TSMP, respectively) of the nanocomposite films. It was found that the f-GO nanoparticles act as multifunctional cross-links as well as reinforcing fillers and significantly augmented the glassy and rubbery state moduli, yield strength, break strength, glass transition temperature, and dual shape-memory properties. A cohesive bilayer of the two films (lower layer and upper layer) fabricated by the interpenetrating polymer network technique exhibited synergistic mechanical properties in the glassy and rubbery states along with two undisturbed glass transitions by which an intermediate plateau region and TSMP were demonstrated.