Bilayer hydrogels with intelligent functions have been considered as the ideal candidates for mimicking soft tissues and robots to adapt their shapes or motions in response to external stimuli. However, conventional fabrication strategies often require multiple complicated steps to create an anisotropic bilayer structure with poor structural defect tolerance due to chemo-mechanical mismatch between two layers. Herein, we report a new working principle and fabrication strategy to construct a family of bilayer hydrogels with a seamless interface and programmable layer thicknesses by controlling spontaneous macrophase separation. The macrophase separation mainly stems from different heat-induced reversible phase transitions of both polymer layers, allowing the decoupling of two gelation processes for the first polymer layer via a typical sol-to-gel transition and the second layer via a spontaneous hydrophilic-to-hydrophobic separation. This work demonstrates a new working principle for seamless integration of thermal-responsive polymers with macrophase separation to create hydrogels with multi-scale hierarchical structures.

具有智能功能的双层水凝胶被认为是模拟软组织和机器人以适应其形状或运动以响应外部刺激的理想候选者。然而，传统的制造策略通常需要多个复杂的步骤来创建各向异性双层结构，由于两层之间的化学机械不匹配，结构缺陷耐受性差。在此，我们报告了一种新的工作原理和制造策略，通过控制自发的巨相分离来构建具有无缝界面和可编程层厚度的双层水凝胶家族。宏观相分离主要源于两个聚合物层的不同热诱导可逆相变，通过典型的溶胶-凝胶转变，允许第一层聚合物层和第二层通过自发的亲水-疏水分离分离两个凝胶化过程。这项工作展示了一种新的工作原理，可以将热响应聚合物与宏观相分离无缝集成，从而创建具有多尺度层次结构的水凝胶。