ABA-Type Thermoplastic Elastomers: From Styrenic and Acrylic Systems to Emerging Bio-Based Materials.

The combined elasticity, processability, and recyclability of thermoplastic elastomers (TPEs) has enabled their widespread adoption across diverse industrial sectors. In particular, TPEs have emerged as attractive alternatives to chemically crosslinked elastomers, contributing to extended product lifetimes and reduced waste generation. Their performance arises from the presence of physical, reversible crosslinks, which allow the integration of elastomeric behaviour with thermoplastic reprocessability. This review provides an overview of recent advances in ABA thermoplastic elastomer (TPE) design, focusing on three major classes: styrenic block copolymers, acrylic-based TPEs, and emerging bio-based systems, with particular emphasis on the latter. Special attention is given to structure-property relationships and the influence of molecular architecture on thermomechanical behaviour. Styrenic block copolymers remain the most established class, offering well-defined phase-separated morphologies and tuneable mechanical properties. Acrylic-based TPEs have attracted increasing interest owing to their superior thermal and oxidative stability and versatile molecular design. We also discuss recent progress in bio-based TPEs derived from renewable resources, which aim to reduce reliance on fossil feedstocks without compromising performance. Finally, we examine current challenges and future perspectives, highlighting the need for sustainable synthetic strategies and advanced TPEs with lower environmental impact.