Anomalous Diffusion in an Aqueous System of a Poly(ethylene oxide)−Poly(propylene oxide)−Poly(ethylene oxide) Triblock Copolymer during Gelation Studied by Pulsed Field Gradient NMR

摘要: The molecular motion of poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) block copolymer in water was investigated during the temperature-induced sol−gel transition with aid pulsed field gradient NMR. strong slowing down diffusive gel regime is accompanied by an increased nonexponentiality spin echo attenuation function. value stretched exponent, describing decay attenuation, decreases increasing temperature, and this trend suggests a broader distribution diffusion coefficients when approaching state. Ordinary behavior observed sol phase, whereas anomalous detected as evolves, mean square displacement 〈z2〉 shows power law dependence on time (〈z2〉 ∝ tα) α < 1. gelation process proceeds, around 0.5 zone, but wave vector can be traced at temperatures regime.