Macroporous-Enabled Highly Deformable Layered Hydrogels with Designed pH Response.

Environment-responsive hydrogel structures are of great interest in materials research and have a wide range of applications. By using a flow lithography technique, we report a one-step and high-throughput fabrication method for the synthesis of highly pH-responsive hydrogels with designed shape transformations. In this method, heterogeneous hydrogels with porous and nonporous layers are synthesized using a single UV exposure in a microfluidic channel. During the UV polymerization, the porous layers, which are formed by using polymerization-induced phase separation (PIPS), significantly increase the swelling capability and enhance the swelling rate of the hydrogels. Because the flow-lithography approach allows various patterns of porous/nonporous layers with great control and enables the simple integration of PIPS, resultant layered hydrogels show extraordinary deformations with desired pH response. More importantly, our fabrication approach can not only make 2D deformation of hydrogel structures such as bending but also can achieve 3D structural deformation such as helical and buckling structures, enabled by nonuniform UV polymerization we developed.