NMR characterization of styrene–divinylbenzene gel beads in swollen state using chloroform as probe

Abstract

AbstractStyrene—divinylbenzene copolymer gel beads in a swollen state were characterized with a proton nuclear magnetic resonance spectroscopy (1H‐NMR) using chloroform as a probe. The signal of chloroform was observed as doublet peaks and the peak at higher magnetic field was assigned to chloroform inside the gel beads and the other at lower magnetic field to one outside the gel beads. NMR parameters such as signal chemical shift, intensity, line width, and shape were investigated in relation to the characteristics of gel beads such as the swelling ratio, the diameter, pore size, and crosslinking density. The relative intensity of the signal due to chloroform inside the gel beads increased with the amount of diluent used in preparation of the beads. With the decrease of the diameter of the beads, two signals became closer, because the rate of exchange between the solvent molecules inside and outside increased. The pore size also influenced the shape of the doublet peaks. As the pore size increased, the two peaks overlapped due to the decrease of the portion of chloroform that interacts with the polymer matrix. The crosslinking density did not influence the peak shape although the dynamics of chloroform were affected by the crosslinking density. © 1995 John Wiley & Sons, Inc.