Copolymerization of 1,6-anhydroglucose and 1,6-anhydromaltose derivatives

The copolymerization of 1,6-anhydro-2,3,4-tri-O-(p-methyl-benzyl)-β-D -glucopyrnose TXGL, M₁] with 1,6-anhydro-2,3-di-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl-α-D -glucopyranosyl)-β-D -glucopyranose HBMA, M₂] has been studied as a method of producing dextrans of controlled composition with a linear backbone and randomly distributed single glucose units as side chains. Copolymers of intrinsic viscosities ranging from 0.51 to 0.05 dl/g are produced. The copolymerization appears to follow classical copolymerization theory but is affected adversely by the low reactivity of the maltose derivative. Reactivity ratios have been calculated for runs catalyzed by 10 mole-% and 20 mole-% phosphorus pentafluoride (PF₅): r₁ = 1.91 ± 0.35, r₂ = 0.28 ± 0.25 and r₁ = 2.21 ± 0.15, r₂ = 0.21 ± 0.10, respectively.