Xerogels of poly(methacrylic acid) (MAXG) with different primary structural parameters (PSP) [number average molar mass between the network crosslinks (Mc), the crosslink degree (?c), and the distance between the macromolecular chains (d)] are successfully synthesized by crosslinking free-radical polymerization. The isothermal swelling curves of synthesized MAXG are measured in distilled water in the temperature range of 2540 degrees C. The swelling conversion curves of all the MAXG may be described with kinetics model of phase boundary controlled reaction, i.e., contracting area (R2). The values of swelling kinetics parameters (Ea and lnA) linearly increase with the increase in Mc. This work presented a novel and quantum model of the mechanism of xerogel's swelling activation process based on resonant coupling of vibration oscillation of water molecules and vibration modes of xerogel. A quantum nature of Ea of swelling process is proved and explained the effects of PSP on the values of swelling kinetics parameters. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013