Mechanical and responsive properties of temperature-responsive gels prepared via atom transfer radical polymerization

Temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) gels were prepared via atom transfer radical polymerization (ATRP), and their mechanical and responsive properties were investigated from the viewpoint of their network homogeneity. When the PNIPAAm gels were prepared by ATRP and free radical polymerization (FRP) at a low temperature, no difference was observed in the mechanical properties. However, the PNIPAAm gels prepared via ATRP at room temperature showed a higher elastic modulus and greater temperature-responsive change than the gels prepared via FRP. The temperature-responsive shrinkage rate of the PNIPAAm gel prepared via ATRP was slower than that of the gel prepared via FRP. Dynamic light scattering (DLS) measurements revealed that these results can be attributed to the more homogeneous network structure in the PNIPAAm gel prepared via ATRP than in the gel prepared via FRP.