Photopatterning Block Copolymer Enables Mechanical Enhancement.

Soft-hard integrated architectures provide a powerful route to mechanical enhancement, but current fabrication methods often suffer from interfacial failure and limited mechanical tunability. We propose a multiscale strategy by combining molecular photoisomerization, nanoscale phase separation, and macroscopic photopatterning in block copolymers. Molecular photoisomerization allows for reversible conformational changes from trans to cis and mechanical tuning from stiffness to soft elastics. Microphase-separated nanodomains permit switching of hard and soft microphases and alter the energy dissipation. Macroscale photopatterning enhances the toughness and guides the cracks. This establishes a multiscale coupling paradigm of molecular response-nanoscale dissipation-macroscopic geometry, addressing interfacial failure and broadening the tunable mechanical region. Using kirigami cutting and conductive layer coating, the system is integrated with complex surfaces to convert mechanical deformation into electrical signals, highlighting its potential in flexible sensing and electronics.