Inhomogeneous swelling

Mallam, S Horkay, F Hecht, A-M Geissler, E, Scattering and Swelling Properties of Inhomogeneous Polyacrylamide Gels, Macromolecules 22, 3356, 1989. 

A. Meissner, P. Bloch, E. Humpfer, M. Spraul and O. W. Sorensen, Reduction of inhomogeneous line broadening in two-dimensional high-resolution MAS NMR spectra of molecules attached to swelled resins in solid-phase synthesis, J. Am. Chem. Soc., 1997, 119, 1787-1788. 

Solutions with overlap (semi-dilute) possess a homogeneous structure on the large scale ( R). However, in between nearest neighbour contacts, the solution is dilute, and therefore inhomogeneous. The repulsive interactions acting on the homogeneous stmcture do dent of the polymer size not combine to swell the structure. On the contrary, compensations occur and on average the interactions screen... 

Attempts to determine the extent of cross-linking in wool fibers, whether untreated or reduced and alkylated, by measurement of swelling in aqueous LiBr or similar solvents (Haly, 1963a Atkinson and Speakman, 1960 Speakman and Stone, 1962, 1963) give results of doubtful significance because of the inhomogeneity of the wool fiber. 

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