Achieving Mechanical Evolution in Polymer Materials Through Phase Evolution Induced by Visible Light.

Abstract

Can artificial polymer materials exhibit the characteristic of "evolution" over time, similar to biological tissue? The limitations arise from their inherently static nature and the absence of dynamic structures. A strategy is proposed for designing polymer materials whose phases and mechanical properties can be continuously transformed and enhanced temporally. Specifically, the polymer phases experience a sequence of transitions involving generation, separation, and fusion. Each period enhances mechanical properties in distinct and significant ways, demonstrating a mechanical evolution. This evolution is initiated through in situ polymerization within the material and can be precisely controlled using visible light. Applied to a hydrogel system, this approach achieves a record-breaking increase in Young's modulus by over 2400-fold, from 18.5 kPa to 44.5 MPa. The findings highlight the potential for tailoring mechanical properties on demand and constructing metamaterials with multilevel moduli and composite architectures.