INFUSION OF POLYMER INTO A POROUS-GLASS BEAD AS STUDIED BY SPACE-RESOLVED JAMIN INTERFEROMETRY

Jamin interferometry was applied to a porous glass bead in order to ob serve transient infusion of solvated polymer into the medium after the polymer was added to the surrounding solvent. Analysis of the fringe pattern along the equator of the bead image allowed us to obtain the c oncentration profile of the polymer at different times during the infu sion. It was found that there are some polymer chains that quickly ent er the pores and spread throughout the medium. Afterward, the concentr ation profile slowly approached an equilibrium uniform distribution. W hen the polymer chain's dimension was smaller than the pore size, the approach was limited by intrapore diffusion of the chains. In contrast , the entrance of polymer chains into the pores near the bead surface was rate-limiting for polymer chains with a dimension larger than the pore size. The rate of entrance increased at higher concentrations. Un like studies of transport through a porous membrane, space-resolved in terferometry of the porous glass has the advantage of being able to di stinguish the entrance from the intrapore diffusion.