Controlled Actuation of Shape-Memory Nanocomposites by Application of an Alternating Magnetic Field

摘要

Shape-memory polymers are smart materials with an high application potential as intelligent implant material e.g. as self adjusting orthodontic wires or selectively pliable tools for small scale surgical procedures. Typically heat or light are used to initiate the shape-memory effect. By incorporating magnetic nanomaterials into shape-memory polymers a non-contact triggering of shape-memory polymers can be realized when the nanocomposite is exposed to an alternating magnetic field. Here we report controlled actuation of shape-memory polymer networks by application of an alternating magnetic field. Shape-memory nanocomposites were prepared by crosslinking of oligo(ε-caprolactone)dimethacrylate in the presence of silica coated nanosized magnetite nanomaterials. Effects of magnetite nanomaterials on the thermal and mechanical properties of the composite have been investigated by means of differential scanning calorimetry (DSC), dynamic mechanical analysis at varied temperature (DMTA) as well as by tensile tests and cyclic thermomechanical experiments. The influence of the nanomaterials on the shape-memory and elastic properties of the nanocomposite are discussed. Finally, the macroscopic shape-memory effect by inductive heating of the nanocomposite samples in an alternating magnetic field (f=258kHz; H=17kA/m) was explored.