Polymer swelling 2: A restudy of poly(styrene‐co‐divinylbenzene) swelling in terms of the cross‐link density¹

A very convenient and reliable gravimetric method was developed for measuring swelling of poly(styrene‐co‐divinylbenzene) in particulate form. The method is based on the gravimetric procedure reported earlier 2 for monitoring liquid uptake by thin (<0.3 mm) microporous composite films, consisting of swellable particulate (80% by weight) enmeshed in poly(tetrafluoroethylene) microfibers (20%). The swellability S (in milliliter of liquid absorbed per gram of polymer in equilibrium with excess liquid) for six sty‐co‐DVB polymers with crosslink densities ranging from 0.01 to 0.12 was measured in 19 organic liquids. In each study of S as a function of the relationship was given by where is the average number of carbon atoms in the “backbone” of the polystyrene segments between cross‐link junction, C is the relative swelling power of the liquid, and is the critical cross‐link density above which S is equal to zero.