Hierarchical network relaxation of a dynamic cross-linked polyolefin elastomer for advanced reversible shape memory effect.

Reversible shape-memory polymers (RSMPs) are highly desired for soft actuators due to the repeatability of deformation. Herein, a polyolefin elastomer vitrimer (POEV) was prepared by constructing a dynamic cross-linked network based on boronic ester bonds. POEV showed varied network relaxation in a wide temperature range due to hierarchical network relaxation, and then the entropy decreased and the relaxation of POEV chains was facilely controlled by temperature.

Configurational Entropy Regulation in Polyolefin Elastomer/Paraffin Wax Vitrimers by Thermally Responsive Liquid-Solid Transition for Force Storage.

The work output of shape memory polymers during shape shifting is desired for practical application as actuators. Herein, a polyolefin elastomer (POE) and paraffin wax (PW) are co-cross-linked by dynamic boronic ester bonds to enhance the network elasticity and the stress transfer between the two phases, endowing high force storage capacity to the prepared vitrimers. Depending on the phase of PW, one-way force storage is realized by programming at a low temperature (25 °C), owing to which solid PW can promote the locking of POE chains in a low-entropy state, while reversible force storage can be realized by programming at a high temperature (75 °C), owing to which the relaxation of chains facilitated by liquid PW can promote the construction of a stable structure.

Self-Sensing Actuators Based on a Stiffness Variable Reversible Shape Memory Polymer Enabled by a Phase Change Material.

Soft actuators with integrated mechanical and actuation properties and self-sensing ability are still a challenge. Herein, a stiffness variable polyolefin elastomer (POE) with a reversible shape memory effect is prepared by introducing a typical phase change material, i.e.

Electro and Light-Active Actuators Based on Reversible Shape-Memory Polymer Composites with Segregated Conductive Networks.

Reversible shape-memory polymers (RSMPs) show great potential in actuating applications because of its repeatability among many other advantages. Indeed, in many cases, multiresponsive RSMPs are more expected, and the strategy to introduce functional fillers without deteriorating the reversible deformation performance is of great importance. Here, a facile strategy to balance the electro, photothermal performance, and molecular chain mobility is reported.