Abstract
Poly(N-isopropylacrylamide) (PNIPAM) hydrogel nanospheres response to global temperature stimuli across the low critical solution temperature is studied as the water content in the polymer network is modified. The refractive index of gel nanoparticles was measured as a function of temperature using spectroscopic ellipsometry. The volume of the nanospheres reduces by 40% resulting in a modification of light scattering properties of the medium. A change in temperature from 33 to 34 °C results in a volume contraction of nanospheres which is accompanied by 8–10% enhancement in the refractive index of the gel network.