Selective entanglement coupling of nanoparticles in polymer nanocomposite with high shape recovery stress

Nanoparticles have been widely used to enhance mechanical properties of polymer matrix, however, the complex mechanisms of interfacial entanglements, coupled confinements and coordinative motions among the polymer macromolecules and nanoparticles have not been well understood. In this study, we develop a coupling model to describe the thermodynamic entanglements and confinement effects within nanoparticle reinforced shape memory polymer (SMP) nanocomposites. We found that thermodynamic relaxation of the SMP nanocomposite is determined by cooperative effects of sub-entanglement and topological entanglement of macromolecule chains, which selectively enhance the relaxation behaviors and enable a high recovery stress of SMP nanocomposites. Finally, the effectiveness of this model is demonstrated by applying it to predict the constitutive relationships and shape memory behaviors, and this fundamental approach can reveal toughening mechanisms of shape recovery strength in the SMP nanocomposites by nanoparticles.