Jiang Lichao, Li Feiyang, Li Yunting, Pi Menghan, Xie Jiacen, Zhang Jie, Guo Hui, Ran Rong, Cui Wei
College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, China.
School of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai, 519082, China.
Adv Mater. 2025 Jun 20:e2508162. doi: 10.1002/adma.202508162.
Conventional hydrogel preparation typically involves the use of solvents (mostly water), which increases the free volume between polymer chains and weakens their interactions, resulting in mechanically weak hydrogels with limited viscoelasticity. Here, a solvent-free synthesis strategy is presented to produce tough, swelling-resistant physical hydrogels with ultra-wide frequency viscoelasticity (loss factor tanδ > 0.3 at 10-10 Hz). This is achieved through the bulk copolymerization of highly miscible hydrophilic and hydrophobic monomers, forming water-free copolymers that develop into phase-separated hydrogels with dense chain entanglements upon equilibration in water. The resulting hydrogel exhibits significant mechanical enhancements over counterparts prepared through classical micellar copolymerization, with stiffness, strength, and fracture toughness increased by up to 81, 46, and 41 times, respectively. As a proof-of-concept demonstration, the tough hydrogel with excellent swelling resistance is applied as a sound-absorbing coating for underwater vehicles, minimizing acoustic interference during marine research through its strong viscoelasticity and near-perfect acoustic impedance matching with water. Unlike conventional solvent-assisted polymerization methods used for hydrogel preparation, bulk copolymerization offers advantages such as ultra-high monomer concentration, pure products, and straightforward process, providing new insights for developing simple yet tough hydrogels that are not only promising for underwater applications but also conducive to theoretical studies.
传统水凝胶制备通常涉及使用溶剂（大多为水），这会增加聚合物链之间的自由体积并削弱它们的相互作用，从而产生机械性能较弱、粘弹性有限的水凝胶。在此，我们提出一种无溶剂合成策略，以制备具有超宽频率粘弹性（在10-10 Hz时损耗因子tanδ>0.3）的坚韧、抗溶胀物理水凝胶。这是通过高度互溶的亲水和疏水单体的本体共聚来实现的，形成无水共聚物，该共聚物在水中平衡时会发展成具有密集链缠结的相分离水凝胶。所得水凝胶相对于通过经典胶束共聚制备的同类产品表现出显著的机械性能增强，其刚度、强度和断裂韧性分别提高了81倍、46倍和41倍。作为概念验证演示，这种具有优异抗溶胀性能的坚韧水凝胶被用作水下航行器的吸声涂层，通过其强大的粘弹性以及与水近乎完美的声阻抗匹配，在海洋研究期间将声学干扰降至最低。与用于水凝胶制备的传统溶剂辅助聚合方法不同，本体共聚具有诸如超高单体浓度、纯产品和工艺简单等优点，为开发简单而坚韧的水凝胶提供了新的见解，这些水凝胶不仅在水下应用中具有前景，而且有利于理论研究。
