Water-swellable, bead copolymer

A water-swellable, cross-linked bead copolymer prepared by the method comprising:

• a. dissolving a monomer mixture consisting essentially of
• 1. an ethylenically-unsaturated radical-polymerizable comonomer having a glycidyl group,
• 2. a cross-linking comonomer having at least two radical-polymerizable .alpha., .beta.-carbon double bonds, but otherwise free of the functional groups found in monomer (1),
• 3. a radical-polymerizable water-soluble mono-unsaturated comonomer,
• comonomers (1), (2), and (3) constituting from about 50 to 100 mol percent of the monomer mixture with the balance, if any, being
• 4. a water-insoluble radical-polymerizable mono-unsaturated compound,
• comonomer (1) comprising at least 2 mol percent, comonomer (2) comprising 0.2 to 5 mol percent, and comonomer (3) comprising at least 10 mol percent of the monomer mixture, in from 20 to 200 percent, by weight of the monomer mixture, of a non-aqueous solvent for said monomer mixture;
• b. combining the solution with a free radical-forming initiator soluble in said solution;
• c. suspending the resulting solution, in the form of droplets, in a continuous phase of a non-polar organic liquid which is immiscible with said non-aqueous solvent and is not a solvent for said monomer or said initiator;
• d. polymerizing said monomer mixture at a temperature at which said initiator forms free radicals, whereby said bead copolymer is formed;
• and
• e. separating said bead copolymer from said continuous phase of organic liquid.