Polymer Distribution in Silica Aerogels Impregnated With Siloxanes by (1)HNuclear Magnetic Resonance Imaging

摘要

Polymer-modified aerogel samples were prepared by vacuum impregnation of silicaaerogels with dimethylsiloxane-vinylmethylsiloxane copolymers. The specimens were characterized by 1H nuclear magnetic resonance (n.m.r.) relaxation measurements. The effects of the polymer molecular weight, irradiation and aerogel density upon the spin-lattice (T(1)) and spin-spin (T(2)) relaxation times were studied. Significant reduction was observed in the T(2) values owing to increases in both aerogel and crosslink densities. 1H n.m.r. images reveal a high degree of heterogeneity in the samples. Distributions maps of the polymer-silica interactions and crosslink density are obtained.