Biodegradable shape memory nanocomposites with thermal and magnetic field responsiveness

摘要

Thermal and magnetic field responsive biodegradable shape memory polymer nanocomposite was prepared with Fe_3O_4 nanoparticles and poly(L-lactides) (PLLA). The magnetic Fe_3O_4 nanoparticles with an average size of 9 nm were initially synthesized by co-precipitation method and then followed by surface modification using oleic acid. The TEM and SEM results show that the surface modified Fe_3O_4 nanoparticles can evenly disperse in chloroform and PLLA polymer matrix. The tensile test results show that the addition of Fe_3O_4 nanoparticles to a PLLA matrix greatly improved the elastic modulus, tensile strength, elongation at break, and the shape memory properties as well. Moreover, the shape recovery process of the nanocomposites driven by an alternating magnetic field was also observed. However, the shape recovery ratio and the recovery speed in an alternating magnetic field are lower than that occurred in 70 °C water. The lower shape recovery ratio and the recovery speed in an alternating magnetic field is attributed to the low frequency and strength of the magnetic field, which lead to small heat generated by Fe _3O_4 nanoparticles.