Phase-Change Thermoplastic Elastomer Blends for Tunable Shape Memory by Physical Design

TLDR

Intelligent polymeric materials are increasingly valued for their low cost, lightweight, processability, and ability to change shape or size in response to stimuli, and thermally programmable shape‑memory polymers rely on an elastic network component and a switching component with a thermal transition to fix and recover strain states. The study aims to create designer shape‑memory materials by blending thermoplastic elastomeric triblock copolymers with a midblock‑selective phase‑change additive to form shape‑memory polymer blends. The authors blend thermoplastic elastomeric triblock copolymers with a phase‑change additive that selectively associates with the midblock, producing shape‑memory polymer blends with tunable transition temperatures. The resulting blends show tunable transition temperatures, controllable recovery kinetics, and can be further utilized in laminate welding for multishape fabrication and liquid‑metal inclusion for shape‑memory electronics.

Abstract

Intelligent polymeric materials are of increasing interest in contemporary technologies due to their low cost, light weight, facile processability, and inherent ability to change properties, shape, and/or size upon exposure to an external stimulus. In this study, we consider thermally programmable shape-memory polymers (SMPs), which typically rely on chemistry-specific macromolecules composed of two functional species. An elastic, network-forming component permits stretched polymer chains to return to their relaxed state, and a switching component affords at least one thermal transition to regulate fixation of a desired strain state and return to a previous strain state. Here, we produce designer shape-memory materials by combining thermoplastic elastomeric triblock copolymers with a midblock-selective phase-change additive, thereby yielding shape-memory polymer blends (SMPBs). These materials not only exhibit tunable switch points but also controllable recovery kinetics. We further highlight the versatility of SMPBs through laminate welding for intermediate multishape fabrication and liquid metal inclusion for shape-memory electronics.