Open AccessTemperature dependence of localised surface plasmon resonance effect on photoisomerisation of azobenzene units in Ag/poly(N‐isopropylacrylamide)‐block‐poly{6‐[4‐(4‐methylphenyl‐azo)phenoxy] hexylacrylate} composite particles
Author(s) -
Zhang Yujuan,
Wu Wenxuan,
Shen Guangyong,
Gao Jiangang,
Zhang Qijin
Publication year - 2014
Publication title -
micro and nano letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.25
H-Index - 31
ISSN - 1750-0443
DOI - 10.1049/mnl.2014.0169
Subject(s) - azobenzene , surface plasmon resonance , composite number , materials science , resonance (particle physics) , poly(n isopropylacrylamide) , surface plasmon , azo compound , block (permutation group theory) , photochemistry , plasmon , polymer chemistry , optoelectronics , chemistry , composite material , copolymer , nanoparticle , nanotechnology , polymer , physics , geometry , mathematics , particle physics
A series of Ag/poly(N‐isopropylacrylamide)‐block‐poly{6‐[4‐(4‐methylphenyl‐azo)phenoxy] hexylacrylate} (PNIPAM‐b‐PAzoM) composite particles (CPAs) with varying concentrations of Ag nanoparticles are prepared by self‐assembly of PNIPAM‐b‐PAzoM in a mixture of H 2 O and THF at first, and then by chemical reduction of AgNO 3 in the suspension of the self‐assembled particles. The distance between Ag nanoparticles and azobenzene units is determined by the concentration of Ag nanoparticles and temperature because hydrophilic poly(N‐isopropylacrylamide) (PNIPAM) chains are thermosensitive and adsorbed with Ag nanoparticles. Both trans‐ to ‐cis and cis‐ to ‐trans photoisomerisations of the CPAs are investigated at different temperatures and concentrations of Ag nanoparticles. Experimental results reveal that, at room temperature, both rates of the trans‐ to ‐cis and the cis‐ to ‐trans photoisomerisations are decreased by the localised surface plasmon resonance of Ag nanoparticles with experimental concentrations lower than 0.04 mmol/l. With the temperature increasing and gradually closing to the low critical solution temperature of PNIPAM chains the rate of the trans‐ to ‐cis photoisomerisation can be found to be enhanced gradually within the same concentration range of Ag nanoparticles. However, the rate of the cis‐ to ‐trans photoisomerisation is little affected. Detailed analysis shows that this effect is related to the overlap of azobenzene absorption and Ag nanoparticle absorption.