Patent ID: 7041730

Claim:
A substituted polysaccharide useful as a macroinitiator for preparing graft polysaccharide polymers by controlled graft polymerisation, in which at least one sugar unit of the polysaccharide is substituted by a group of the formula —W—(X) p -(L) q -(Y) r -Z in which W represents a group —O— or —NR 1 —, where R 1 represents a hydrogen atom or an optionally substituted alkyl group, preferably a hydrogen atom; p, q and r are each Independently 0 or 1; L represents an optionally substituted alkylene, cycloalkylene, arylene or heteroarylene group; X and Y each independently represent a group —CH 2 —, —CO—, —O—CO—, —CO—O—, —NH—CO—, —CO—NH—, —CH(OH)—CH 2 —, —CH 2 —CH(OH)—, —CH 2 —O—CO—, —CO—O—CH 2 —, —CH 2 —CO—O—, —O—CO—CH 2 —, —O—CO—NH—, —NH—CO—O—, —(CR 2 R 3 ) s —CO—, —CO—(CR 2 R 3 ) s —, —(CR 2 R 3 ) t —O—, —O—(CR 2 R 3 )t—, —(CR 2 R 3 ) u —SO—, —SO—(CR 2 R 3 ) u —, —(CR 2 R 3 ) v —SO2—, —SO 2 —(CR 2 R 3 ) v — or —NH—CO—NH, where s, t, u and v are each independently 0, 1, 2 or 3 and R 2 and R 3 each independently represent a hydrogen atom or an optionally substituted alkyl group; and Z comprises a halogen atom and represents a control agent site from which a polymer may propagate during a free radical polymerisation process, the substituted polysaccharide having the general formula wherein each SU represents a sugar unit in a polysaccharide backbone; a represents the number of unsubstituted sugar units as a percentage of the total number of sugar units and is in the range from 0 to 99.9%, b represents the number of substituted sugar units as a percentage of the total number of sugar units and is in the range from 0.1 to 100%, preferably 1 to 35%, more preferably 1 to 20%; m represents the degree of substitution per sugar unit and is from 1 to 3, in which the polysaccharide has a β-1,4-linked backbone.