Shape Memory Polymer Nanocomposites: Impact of Nanoparticles on Energy Storage, Strain Set and Recovery

Shape memory polymers (SMPs) are being increasingly examined for technologies ranging from biomedical implants to morphing structures due to their ability to recover deformations >500% or exert recovery stresses of up to 5MPa.   Two general classes of SMPs can be identified relative to the internal strain-trapping process responsible for inhibiting relaxation of the distorted polymer chains and thus “locking-in” the temporary shape – those based on a thermal quench or on the strain-induced creation of a reversible physical cross-link, such as crystallites or a micro-phase transition.  This talk will consider how polymer nanocomposite concepts can enhance the performance of shape memory polymers (SMPs).  Maximum impact of nanoparticle addition has been observed at high deformations of rubbery SMPs exhibiting strain-induced crystallization   Overall, the extent to which nanoparticle addition impacts the shape memory performance is directly governed by the extent to which nanoparticle aspect ratio, hierarchical morphology and interfacial interactions impacts the molecular mechanism responsible for trapping elastic strain.  As for shape recovery, the addition of nanoparticles may increase thermal conductivity and provide alternative volumetric heating processes, such as electrical current, microwave radiation or infrared light.  These advantages can be realized independent of the underlying strain set mechanism of the SMP.