Adaptive dry adhesives with tunable morphology via shape memory elastomeric bilayers

Dry adhesives offer appealing advantages such as reusability and clean detachment, yet their performance is fundamentally constrained by the trade-off between adhesion strength and fracture toughness. In this work, we present adaptive bilayer dry adhesives that integrate a thin, compliant elastomeric polydimethylsiloxane (PDMS) surface with a stiff shape memory polymer (SMP) backing layer. While the SMP layer enables shape programming through its rubber-to-glass transition, the PDMS layer suppresses catastrophic adhesive failure and preserves adhesion. Finite element analysis results reveal that the programmed bilayer surface forms extensive interfacial contact with minimal preload, outperforming conventional elastomeric adhesives. Adhesion tests further demonstrate that the bilayer achieves nearly ten-fold higher adhesion compared to PDMS, while maintaining greater detachment toughness relative to SMP, thereby alleviating the inherent trade-off. Moreover, the bilayer’s shape programming capability enables stable and repeatable adhesion to curved surfaces without requiring additional rubber-to-glass transitions. For practical demonstrations, we fabricated an integrated heater-assisted adhesive hook capable of supporting a 2 kg load on diverse wall surfaces, with reversible and reusable operation. This bilayer adhesive strategy provides a generalized design principle to overcome the incompatibility between adhesion and toughness, offering strong potential for applications in soft robotics, wearable systems, and transfer printing.

干态胶粘剂（dry adhesives）具备可重复使用、无损剥离等优异特性，但其性能始终受限于粘附强度与断裂韧性之间的固有权衡。本研究提出一种自适应双层干态胶粘剂，其将薄而柔顺的弹性体聚二甲基硅氧烷（PDMS）表层与硬质形状记忆聚合物（SMP）背层相结合。SMP层可通过橡胶态-玻璃态转变实现形状调控，PDMS层则可抑制灾难性粘附失效并维持粘附性能。有限元分析（finite element analysis）结果表明，经形状调控的双层表面可在极低预载荷下实现大面积界面接触，性能优于传统弹性体胶粘剂。粘附性能测试进一步证实，与纯PDMS胶粘剂相比，该双层胶粘剂的粘附强度提升近10倍，同时相较纯SMP胶粘剂具备更优异的剥离韧性，从而缓解了二者间的固有权衡矛盾。此外，该双层结构的形状调控能力可使其在无需额外进行橡胶态-玻璃态转变的前提下，实现对曲面的稳定、可重复粘附。为验证实际应用潜力，我们制备了集成加热辅助功能的胶粘剂挂钩，该挂钩可在多种墙面支撑2千克载荷，且具备可逆可重复的使用性能。该双层胶粘剂设计策略为解决粘附性能与韧性间的兼容性难题提供了通用化设计思路，在软体机器人、可穿戴系统及转印技术等领域具备广阔应用前景。