Optimising Viscoelastic Window in Reversible Liquid Crystal Elastomer-Based Pressure Sensitive Adhesives via Chain Transfer

Reversible adhesives that can be debonded and reused on demand are essential for next-generation sustainable electronics assembly, biomedical devices, and soft reconfigurable systems. Liquid crystal elastomer (LCE) exhibits dynamic adhesion leveraging their thermomechanical responsiveness and tunable bulk rheological behaviour. However, existing LCE adhesives often require extended contact period or thermal annealing to attain sufficient tack, which significantly limits their broader application. Here, we present a scalable chain-transfer reaction strategy using commercially available agents to directly regulate the viscoelastic properties of LCEs. This approach enables an ‘ideal’ pressure-sensitive adhesive (PSA), satisfying the Dahlquist criterion without any tackifier or thermal conditioning while maintaining the excellent reversibility. The resulting LCEs exhibit a low glass transition temperature (− 11°C) and a storage modulus of 0.1 MPa at room temperature. They also display strong adhesion owing to their exceptional viscoelastic dissipation, with a peak loss factor (tan δ) of 1.85 and a broad high damping plateau (tan δ ≈ 0.91) within the nematic phase. Remarkably, both the peel and tack strengths remain comparable before and after annealing, outperforming conventional LCE-based adhesives that depend on time- or heat-assisted wetting. This work provides a new design strategy for high-performance, debondable, and reusable adhesives, paving the way for more sustainable and smart adhesive technologies.