Controlled shape memory effects of magnetic polymer nanocomposites by induction heating

Interest in stimuli-responsive materials has increased rapidly, leading to a multitude of innovative applications in biomedical design. This study seeks to induce controlled shape memory effects through induction heating of magnetic polymer nanocomposites while retaining thermal consistency within attached hydrogel composites for various biomedical applications. Three commonly used polymer matrices were embedded with varying concentrations of magnetite nanoparticles to determine minimum and maximum loading effects on induction heating response and optimal shape memory effects. Thermal and morphological characterizations were performed to determine transition temperatures, followed by induction heating tests by way of an induction coil at different magnetic field strengths to determine heating rates, activation times and activation rates of shape memory effects for each polymer nanocomposite composition. Simultaneously, mechanically tunable sodium alginate and cellulose nanocrystal hydrogel composites were fabricated and characterized to determine hydrational, mechanical and thermal buffering properties. Induction heating tests revealed that all substrates exhibited a heating response; however, shape memory effects were observed only in poly(vinyl acetate) and Nylon 11. Moreover, all hydrogels displayed promising thermal dissipation, <1°C per 20 s of heating, preventing any potential thermal shock to biological components. These unique properties will allow for successful employment of these multi-composite scaffolds in a multitude of biological applications.