Fig. 4.

Light-enabled reversible self-assembly of Au NPs intimately and permanently capped with photoresponsive polymer chains. Chemical structures of (A) coumarin and (B) MAMC (i.e., Fig. 1, Center Right). (C) Schematic illustration of photodimerization (photo–cross-linking) and photocleavage behaviors of PMAMC chains situated on the surface of Au NPs when subjected to 365- and 254-nm UV light irradiation, respectively. (D) Stepwise representation of light-enabled self-assembly and disassembly of PMAMC-capped Au NPs upon 365- and 254-nm UV light irradiation, respectively. The thicker green ring in D represents the complete photo–cross-linking of PMAMC chains, whereas the thinner green ring depicts the incomplete photocleavage (SI Appendix and SI Appendix, Figs. S36 and S37).