Freely-shapable fabrication of aerogel patterns and 3D architectures by freeze-assisted transfer printing

Herein, we propose a freeze-assisted transfer printing strategy to realize freely-shapable fabrication of graphene aerogels. The competition of interfacial adhesion between the stamp and substrate was evaluated, providing the basis for controllable positioning and shaping of patterned aerogel arrays. Taking advantage of the diverse geometry building blocks, large area or complex 3D aerogel architectures can be prepared efficiently. This strategy is compatible with various concentrations of graphene inks and has no viscosity dependence, so aerogel patterns of different densities can be printed in a single pass. A gradient graphene aerogel was prepared by multilayer printing, satisfying the sensitive pressure sensing under both small deformation and large strain conditions. In addition, we have demonstrated that the strategy is applicable to abundant colloidal systems including composite nanomaterials and biopolymers. Therefore, heterogeneous aerogel structures can be realized through the principle of laminated printing using multiple materials. A bilayer aerogel with an auxetic pattern was designed, which showed magnetically controlled stretchability and stable conductivity. This demonstrates the potential application of our approach in functional device integration.