Hydrophilic gels of poly(trimethylolpropane trimethacrylate-co-acrylamide)

Abstract

Bulk polymerization of trimethylolpropane trimethacrylate (TRIM) and acrylamide resulted in blockpolymers. Ethyl acetate was used as the pore forming agent. The concentration of acrylamide was varied. Characterization of the polymers was done with mercury porosimetry, nitrogen adsorption-desorption technique, elemental analysis of nitrogen, solid state (CP-MAS-DD) 13C NMR, pycnometer, and by swelling experiments. The amount of detected nitrogen showed that 85% or more of the added amount of acrylamide had polymerized. The amount of unreacted double bonds decreased as the amount of acrylamide in the polymer increased. The gel, consisting of 27.5 mol % acrylamide, swelled to the same extent in hydrophilic as well as in organic solvents. The BET [1] surface area of poly(TRIM-co-acrylamide) gels increased slightly with the amount of acrylamide (up to 18 mol % acrylamide) in the gel. For polymers with a higher content of acrylamide, the inner surface decreased. The pore size distribution of small pores ( d ≤ 100 A ̊ ) showed a decrease in the number of pores when the amount of acrylamide in the gels increased. The differential pore volume of large pores ( d ≥ 100 A ̊ ) increased as the amount of acrylamide decreased. The elution volumes for proteins of different molecular weights were determined.