Buffer effects on aqueous swelling kinetics of polyelectrolyte gels

Abstract

Electrolytes are often added to a gel‐swelling medium under the assumption that the important conditions which characterize swelling rates are the solution pH and ionic strength, with little emphasis on the nature of the electrolyte. Previous research by Siegel et al. has indicated that the presence of the un‐ionized acidic form of an electrolyte buffer is a primary rate determinant for swelling of a polybase gel. A systematic swelling study on two separate gels, 2‐hydroxyethyl methacrylate copolymerized with methacrylic acid (HEMA/MAA) and N,N‐dimethylaminoethyl methacrylate (HEMA/DMA), has been performed to investigate the influence of the concentration of the un‐ionized buffer by three principal factors: (1) total buffer concentration, (2) solution pH, and (3) buffer pKa. Swelling and deswelling kinetics were obtained. In the presence of an electrolyte buffer, a dramatic swelling rate increase is observed for the HEMA gels, with substantial gains in rate obtained as total buffer concentration rises. Results also emphasize that to enhance swelling kinetics, the pH must be such that the buffer is essentially un‐ionized.

Partitioning of hexavalent chromium in temperature-sensitive, polyelectrolyte hydrogels

“…Similar effects of salt chemistry on gel swelling have been reported earlier (23,24) Partitioning of CrCVD Anions Figure 3 presents experimental data for the partition coefficients of Cr(VI) into NIPA/MAPTAC gels of 0-3% CM in aqueous potassium dichromate solutions at 22°C. Data also appear in Table 2.…”

Development of a Model for Analyzing the Swelling Rate of Ionic Gels on the Basis of the Diffusion of Mobile Ions: Application to the pH-Sensitive Swelling of a Polyelectrolyte Complex Gel Prepared from Xanthan and Chitosan

“…2(a) and 2(b) were used in the calculation as the boundary conditions for Eq. (15) and as the function f for Eq. (16), respectively.…”

pH sensitivity and ion sensitivity of hydrogels based on complex-forming chitosan/silk fibroin interpenetrating polymer network

“…[5][6][7][8][9] In recent Contract grant sponsor: National Natural Science Foundayears, it was found that some of the polymer comtion of China.…”