Synthesis of thiol-terminated thermoresponsive polymers and their enhancement effect on optical limiting property of gold nanoparticles

Thermoresponsive thiol-terminated poly(N-isopropylacrylamide) (PNIPAM) and diblock poly(ethylene glycol)b-poly(N-isopropylacrylamide) (PEG-b-PNIPAM) were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization and aminolysis reaction. The lower critical solution temperature (LCST) of the polymers increases with the increase of PEG chain segment. Such polymers were used to modify gold nanoparticles (AuNPs) by Au-S bonds. The optical limiting property of the polymer-stabilized gold nanoparticles was investigated, and the results show that the thermoresponsive polymer-stabilized gold nanoparticles exhibit enhanced optical limiting effect relative to pristine AuNPs. The higher optical limiting energy threshold was observed for gold nanoparticles stabilized with polymers having higher LCST.