Preparation of RF-(VM-SiO2)n-RF/AM-Cellu Nanocomposites, and Use Thereof for the Modification of Glass and Filter Paper Surfaces: Creation of a Glass Thermoresponsive Switching Behavior and an Efficient Separation Paper Membrane.

Fluoroalkyl end-capped vinyltrimethoxysilane oligomeric silica/alkyl-modified cellulose (AM-Cellu) nanocomposites [RF-(CH2-CHSiO2)n-RF/AM-Cellu; n = 2, 3; RF = CF(CF3)OC3F7] were prepared by the sol-gel reactions of the corresponding oligomer [RF-(CH2-CHSi(OMe)3)n-RF] in the presence of AM-Cellu. The nanocomposites thus obtained were applied to the surface modification of glass to exhibit a highly oleophobic/superhydrophilic characteristic on the modified surface at 20 °C. Interestingly, a temperature dependence of contact angle values of dodecane and water was observed on the modified surface at 20~70 °C, and the dodecane contact angle values were found to decrease with increasing the temperatures from 20 to 70 °C to provide from highly oleophobic to superoleophilic characteristics on the surface. On the other hand, the increase of the water contact angle values was observed with the increase in the temperatures under similar conditions to supply superhydrophilic to superhydrophobic characteristics on the modified surface. The corresponding nanocomposites were also applied to the surface modification of the filter paper under similar conditions to afford a superoleophilic/superhydrophobic characteristic on the surface. It was demonstrated that the modified filter paper is effective for the separation membrane for W/O emulsion to isolate the transparent colorless oil.