| abstract |
A method of making a copolymer of meta- or para- isopropenyl-a,a-dimethylbenzylisocyanate and at least one other ethylenically unsaturated comonomer polymerizable therewith, comprising polymerizing the meta- or para- isopropenyl-a,a-dimethylbenzylisocyanate and at least one other ethylenically unsaturated comonomer in an aqueous emulsion in the presence of a free-radical polymerization initiator and a chain transfer agent to control molecular weight. n Also disclosed are methods of breaking the aqueous emulsion after polymerization is completed by either adding a salt, e.g., aluminum sulfate, or by freezing the emulsion followed by thawing to yield the copolymer as a mechanically separable solid phase of a two-phase liquid-solid mixture. |