Multi-modal commutative dynamics in semi-crystalline polymers undergoing multiple shape memory behavior

Semi-crystalline polymers offer great opportunities for design and tuning of multi shape memory effect (multi-SME) through their programmable melting transitions. However, coexistence of amorphous and crystalline components as well as their multiple interfaces results in complex cooperative dynamics. In this study, we propose a one-dimensional (1D) multi-modal dynamic model to describe the commutative and cooperative dynamics in semi-crystalline shape memory polymers (SMPs) undergoing multi-SME. A three-phase model and Takayanagi principle are firstly applied to study the cooperative dynamics of amorphous/crystalline components and their interfaces. Phase transition theory and modified Avrami theory are further used to model the cooperative dynamics of glass and melting transitions, respectively. Commutative dynamics and glass/melting transitions are further investigated to achieve custom-designed multi-SME and shape recovery behaviors. Finally, effectiveness of the newly established model was demonstrated to predict triple-SMEs and quadruple-SMEs in semi-crystalline polymers reported in literature, and the theoretically obtained results show good agreements with the experimental ones.