Graft copolymers of methyl methacrylate and α-methylstyrene sulphonate: Preparation and use as stabilisers in aqueous electrolyte solutions

Abstract

Graft copolymers of methyl methacrylate and α-methylstyrene were synthesised and then sulphonated to produce graft copolymers comprising a water insoluble, poly-(methyl methacrylate) backbone and water soluble, poly(α-methylstyrene sulphonate) side chains. Adsorption of the copolymers on polystyrene latex from aqueous solutions containing added sodium chloride was studied. The extent of adsorption was found to increase with increasing ionic strength. Latices stabilised by polyelectrolyte copolymers in which the poly(α-methylstyrene sulphonate) chains had degrees of polymerisation (DP's) ⪢ 14 were found to be stable in saturated solutions of sodium chloride (ca. 6.0 mol dm −3) and calcium chloride (ca. 6.6 mol dm −35) over the temperature range 5–95°C. However. when the DP = 8.0, flocculation of stabilised latices was observed at 20°C in the presence of 1.6 mol dm −3 sodium chloride.