Polymers from sugars and CS2: ring opening copolymerisation of a d-xylose anhydrosugar oxetane

Abstract

A D-xylose anhydro sugar derivative (1) has been applied in the ring-opening copolymerisation (ROCOP) with CS₂ to form a polythiocarbonate (poly(CS₂-co-1)) with high head-head/tail-tail regioselectivity towards alternating thiono- and trithiocarbonate linkages (up to 95%). Through variation of the reaction parameters (e.g. temperature and CS₂ stoichiometry), some control over the regioselectivity (head-head/tail-tail linkages 57–95%) and the nature of the polymer linkages is possible. Conditions can also be tailored to enable the facile isolation of a polymerisable cyclic xanthate, 2. Kinetic experiments suggest that across the range of temperatures studied, the formation of poly(CS₂-co-1) proceeds at least partially by direct copolymerisation of 1 and CS₂, without necessarily going through the ring-opening polymerisation (ROP) of 2. Poly(CS₂-co-1) exhibits partial chemical recyclability into cyclic monomer 2 (up to 45% after 20 h at 110 °C with [poly(CS₂-co-1)]₀ = 1.34 mol L^−L). Finally, rapid degradation (<1 h) of poly(CS₂-co-1) is possible under UV radiation (λ = 365 nm) and is accelerated in the presence of tris(trimethylsilyl)silane (TTMSS).