Dilute gelling systems: copolymers of styrene and glycol dimethacrylates

Gelation properties of the copolymers of styrene with various proportions of ¹⁴C labelled ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol (MW = 400) dimethacrylate have been studied. The thermal copolymerizations were carried out in 15% (v/v) solution in toluene. The rates of polymerization were found to increase with larger proportions of dimethacrylate cross-linking agents. The conversion at the gel point was surprisingly constant over a wide range of crosslinker concentration. The fraction of crosslinker saturated at both ends was found to increase in the order ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol 400 dimethacrylate. The proportion of completely reacted crosslinker increased only slowly with conversion. At very high concentrations of crosslinker, the onset of inhomogeneity was observed as described previously by Storey³ and Dusek¹⁸.