Self-Healing, Recyclable Syndiotactic 1,2-Polybutadiene-Based Thermadapt Shape Memory Polymers with Cold-Programmed Shape Memory Effect

Shape memory polymers (SMPs), as a type of smart material, play a significant role in practical applications. Unlike the hot programming of SMPs, the cold programming of SMPs does not require preheating. They can undergo deformation and fix a temporary shape at a specific temperature and can be restored upon heating. SMPs typically require internal cross-linking to "remember" their permanent shape. However, cross-linked materials cannot be recycled, resulting in resource waste and environmental pollution. Drawing inspiration from dynamic covalent cross-linking technology, for the first time, this paper integrates the cold-programmed shape memory effect into thermadapt SMPs with syndiotactic 1,2-polybutadiene (SPB) as the matrix. To construct a thermadapt SMPs, this paper first obtained epoxidized syndiotactic 1,2-polybutadiene (ESPB) by epoxidizing SPB. Then, ESPB was mixed with carboxy-terminated liquid polybutadiene rubber (CTPB), resulting in the formation of β-hydroxyl ester dynamic bonds within the material. By regulating the internal cross-linking structure, its glass transition temperature (Tg) can be controlled. Furthermore, the molecular chain of the composite has a regular structure that enables stretching-induced crystallization. This enhances the material's ability to retain its temporary shape during cold programming. This paper provides a feasible and straightforward approach for the preparation of recyclable thermadapt SMPs with cold-programmed shape memory effect and paves the way for the recycling and long-term utilization of SMPs.