Li Li, Wu Baohu, Sun Shengtong, Wu Peiyi
State Key Laboratory of Advanced Fiber Materials, College of Chemistry and Chemical Engineering & Center for Advanced Low-Dimension Materials, Donghua University, Shanghai 201620, China.
Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) Forschungszentrum Jülich, Garching 85748, Germany.
Natl Sci Rev. 2025 Feb 27;12(4):nwaf072. doi: 10.1093/nsr/nwaf072. eCollection 2025 Apr.
Thermal-stiffening hydrogels exhibit a dramatic soft-to-stiff transition upon heating, making them ideal candidates for temperature-triggered self-protection and shape memory applications. However, their practical use is still hampered by a slow recovery process (generally >30 min) during cooling, attributed to sluggish mass diffusion and delayed phase dissolution. Herein, we present a high-entropy phase separation design to significantly accelerate the recovery dynamics of these materials. We demonstrate this concept using a thermal-stiffening poly(calcium acrylate)-based copolymer hydrogel by incorporating hydrophilic units. Mechanistically, the hydrophilic units disrupt the dense packing of thermal-stiffening clusters, creating a high-entropy topological structure with a low energy barrier for rapid mass diffusion. This approach retains the impressive thermal-stiffening response with a 760-fold increase in storage modulus, while dramatically reducing the characteristic recovery time to merely 28 s. We anticipate this high-entropy strategy to be broadly applicable in designing modulus-adaptive materials with fast switching dynamics.
热致硬化水凝胶在加热时会表现出从柔软到坚硬的显著转变，使其成为温度触发的自我保护和形状记忆应用的理想候选材料。然而，它们的实际应用仍然受到冷却过程中缓慢恢复过程（通常>30分钟）的阻碍，这归因于缓慢的质量扩散和延迟的相溶解。在此，我们提出了一种高熵相分离设计，以显著加速这些材料的恢复动力学。我们通过引入亲水性单元，使用基于热致硬化聚丙烯酸钙的共聚物水凝胶来证明这一概念。从机理上讲，亲水性单元破坏了热致硬化簇的紧密堆积，创造了一种具有低能量势垒的高熵拓扑结构，有利于快速质量扩散。这种方法保留了令人印象深刻的热致硬化响应，储能模量提高了760倍，同时将特征恢复时间显著缩短至仅28秒。我们预计这种高熵策略将广泛应用于设计具有快速切换动力学的模量自适应材料。
