Characterization of Flexibly Linked Shape Memory Polyurethane Composite with Magnetic Property

A flexibly cross-linked shape memory polyurethane (SMPU) was converted to a magnetic polymer by making a composite with a ferromagnetic particle (Fe3O4). The flexibly cross-linked SMPU has already displayed excellent mechanical and shape memory properties; the design of a magnetically responsive material allowed for a unique and novel SMPU. Among the three different composite preparation methods (melt-mixing, solvent blending, and in situ reaction mixing), the melt-mixing method was the best and attained even distribution of magnetic particles and high mechanical and shape memory properties. Differential scanning calorimetric and infrared results showed that the polymer structure was not affected by melt-mixing. In tensile testing, the maximum stress of the composite reached 39 MPa, and the strain at break also increased to 2495%. Shape recovery exhibited maximums as high as 99% and displayed similar values after repetitive shape recovery test cycles. Finally, the magnetic property of SMPU was characterized by a superconducting quantum interference device magnetometer and demonstrated in the magnetic attraction test. The potential applications of the magnetic and flexible SMPU are discussed.