Poly(N-isopropylacrylamide) (PNIPAM) was coated on gold nanorods (NRs) without forming aggregates. The PNIPAM-coated NRs (PNIPAM-NRs) formed aggregates at higher temperature than the lower critical solution temperature (LCST) of the PNIPAM layers. The aggregation showed reversible spectroscopic responses under repeated temperature cycles. When a PNIPAM-NR solution was irradiated with near-infrared (near-IR) light, the temperature increased and aggregates formed showing broad and weak surface plasmon bands. The spectroscopic responses in near-IR work as a negative feedback for heating a photoirradiated nanorod solution. The feedback offers spontaneous temperature control of the photoirradiated solution at the LCST of PNIPAM.
2013 The Chemical Society of Japan