SCALING APPROACH TO DIFFERENTIAL SWELLING OF POLYMER-SOLUTIONS AND GELS

The failure of the classical theories for swollen polymer networks was clearly demonstrated by recent differential swelling experiments of G ee, Eichinger and McKenna. We introduce a weaker form of the additivit y assumption based on the separation of the gel into ''solid''-like an d ''liquid''-like components. Using simple scaling arguments and the a ssumption that the effective solvent quality for a crosslinked polymer system is worse than for its uncrosslinked counterpart, we predict a similar anomaly of the swelling activity parameter (dilation modulus) in osmotic deswelling experiments in the semi-dilute range of concentr ation. The relevance to Eichinger's and McKenna's experiments on conce ntrated systems is discussed.