화학공학소재연구정보센터
Macromolecules, Vol.53, No.21, 9313-9324, 2020
Energy Dissipation and Mechanoresponsive Color Evaluation of a Poly(n-hexyl Methacrylate) Soft Material Enhanced by a Mechanochromic Cross-Linker with Dynamic Covalent Bonds
A rigid and brittle cross-linking structure was introduced into the flexible poly(n-hexyl methacrylate) (PHMA) network by the mechanochromic cross-linker difluorenylsuccinonitrile-containing methacrylate (DFMA), whose central C-C bond acted as a dynamic covalent bond and could generate pink radicals when fractured. PHMA with DFMA showed a remarkable hysteresis loop and mechanical enhancement. After deformation, the reassociation of dynamic covalent bonds and the reorganization of the network structure slowed down the recovery of the polymer to its initial state. The correlations between tension stimulation, energy dissipation, and mechanoresponsive color change were discussed. Under stress, the polymer changed from light gray to pink. The broad distribution of red channel intensity under large deformation detected on the surface confirmed that the rupture of dynamic covalent bonds occurred evenly throughout the polymer and suppressed stress concentration. The color showed a strong dependence on stress, which started to appear at around 1.5 to 2.0 MPa. The incorporation of DFMA promised mechanical enhancement and noncontact stress detection ability of the PHMA soft material.