Shape-Memory Properties of Nanocomposites based on Poly(Omega-pentadecalactone) and Magnetic Nanoparticles


Magneto-sensitive shape-memory polymers (SMP) obtained by incorporating magnetic nanoparticles in a SMP matrix are an emerging class of multifunctional materials. The incorporation of the nanoparticles enhanced the mechanical properties and in addition enabled remote actuation by exposure to alternating magnetic fields. Here, we report on the thermallyinduced shape-memory properties of such magneto-sensitive nanocomposites based on poly(ω- pentadecalactone) (PPDL) switching segments and magnetic nanoparticles. A series of nanocomposites were prepared by crosslinking of poly(ω-pentadecalactone)dimethacrylate (Mn = 2800 g·mol-1and 5100 g·mol-1) in the presence of silica encapsulated magnetic nanoparticles. The silica shell of the nanoparticles was selected to enhance the distribution and compatibility of the nanoparticles with the polymer matrix. Thermal and mechanical properties of the nanocomposites were explored as a function of PPDL chain length and nanoparticle weight content. All nanocomposites exhibited excellent shape-memory properties with shape fixity rates between 86% and 93% and shape recovery rates above 97%. Potential applications for such shape-memory nanocomposites include smart implants, medical instruments, which could be controlled on demand by thermal or indirect magnetic heating.
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