Influence of gel preparation concentration on statistical mechanics of poly(dialkylaminoethyl methacrylate) gels on the basis of scaling concept: Toward tunable elasticity and thermomechanical parameters

Abstract

ABSTRACTIn order to evaluate the scaling parameters of weakly cationic crosslinked network structures, poly(dialkylaminoethyl methacrylate)‐based hydrogels were synthesized via free‐radical crosslinking in aqueous solution varying systematically concentration of pregel solution. Based on the gel‐preparation concentration, variation in structural properties, effective crosslinking density, average molecular weight of polymer chains, and thermodynamic parameters from combined swelling and elasticity results were discussed using thescalingtheory to predict various exponent identities. The concentration dependence of compressive elastic modulus as‐prepared state was described by a power‐law relationshipwith the exponent ofm= 3.55 indicating the importance of the trapped entanglements. Two structural characteristics, the network chain lengthNand the average molecular weight of polymer chains have inverse dependence on the gel‐preparation concentration in the matrix, while the compressive moduli and effective crosslinking density show completely direct dependence. Experimentally determinedNvalues of PDMAEMA hydrogels first decrease with increasingup to 0.2972 and the dependence ofNon the gel‐preparation concentration gives the relationwith a scaling parametern= −1.80, which coincides with the prediction of scaling theory. Acceptable agreement was found between the estimate of crosslink density fluctuations deduced from mechanical measurements and the results derived from independent swelling observations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 48350.