Process for preparing high polymeric substance having saccharide side chains

A process for preparing a high polymeric substance having saccharide side chains represented by the formula:

• ##STR18## wherein R represents a hydrogen atom or a methyl group and R' represents a residue of a saccharide selected from the group consisting of glucose, fructose, maltose, mannose, lactose and cellobiose, which is acyl-bonded at its 1-position, and n is an integer of 10 to 1000, which comprises:
• reacting methacrylic acid or acrylic acid with a compound selected from the group consisting of
• 3. 4,6-tri-O-acetyl-glucose 1,2-ethylorthoacetate,
• 3,4,6-tri-O-acetyl-fructose 1,2-ethylorthoacetate,
• 3,6,2',3',4',6'-hexa-O-acetyl-maltose 1,2-ethylorthoacetate,
• 3,4,6-tri-O-acetyl-mannose 1,2-ethylorthoacetate,
• 3,6,2',3',4',6'-hexa-O-acetyl-lactose 1,2-ethylorthoacetate
• and 3,6,2',3',4',6'-hexa-O-acetyl-cellobiose 1,2-ethylorthoacetate to obtain a monomeric compound,
• polymerizing said monomeric compound in an inert solvent in the presence of an initiator for radial polymerization at a temperature of 10.degree. to 200.degree. C., and
• de-acetylating the thus polymerized substance by using a de-acetylating agent at a temperature not more than room temperature.