Attempts to Optimizing the Synthesis of Hypercrosslinked Polystyrene. 1. Crosslinking with Monochlorodimethyl Ether

Abstract

This contribution was focused on the developing of an improved method for preparing hypercrosslinked polystyrene by bridging styrene-0.5% DVB copolymer with monochlorodimethyl ether (MCDE) up to 100, 150, 200 and 300% via Fidel–Crafts reaction. The modification comprises both the reduction in the consumption of the catalyst, SnCl₄, and the complete substitution of SnCl₄ with the more active and less expensive catalyst, FeCl₃. Reducing the SnCl₄ quantity from 1.0 to 0.1 mol per one mole of the ether leads to the formation of hypercrosslinked networks which exhibit a quite good swelling in non-solvents, rater low apparent density, and a noticeable pore volume, but, surprisingly, to a dramatic reduction in the measured inner surface area. The latter finding could be explained by the formation in the networks with very narrow pores which remain inaccessible to the testing argon atoms. The situation changes cardinally if the reaction mixture is additionally provided with oxalyl chloride (0.5 mol per mol of the ether) which reacts with methanol at the moment of its formation during the reaction of the ether with polystyrene. The latter reaction proceeds so violently that it is possible to reduce the amount of SnCl₄ by a factor of at least 13 or diminish the essential portion of FeCl₃ by a factor of 30, compared to the recommended previously 0.3 mol FeCl₃ per one mole of the MCDE.