Relatively homogeneous network structures of temperature-responsive gels synthesized atom transfer radical polymerization.

The network structures of poly(-isopropylacrylamide) (PNIPAAm) gels prepared by atom transfer radical polymerization (ATRP) were compared with those prepared by free radical polymerization (FRP), as a conventional radical polymerization. Temperature-responsive shrinkage was observed in the PNIPAAm gels prepared by ATRP and FRP (ATRP and FRP gels), which depended on the cross-linker content. From the light-scattered intensities, 〈〉, measured at the different sample positions, we used the partial heterodyne method to determine the dynamic fluctuation, 〈〉, spatial component, 〈〉, and correlation length, , of the ATRP and FRP gels, as a function of the cross-linker content and temperature.