Patent ID: 7820764

Claim:
A process to control the molecular weight of styrene polymers in which α-methyl styrene dimer is used as a chain transfer agent, comprising the steps of: (a) providing an essentially solventless blend of: (i) monomers of styrene; (ii) a polymerization initiator; and (iii) α-methyl styrene dimer, (b) feeding the monomer/polymerization initiator blend into a reaction vessel; (c) reacting the monomer/polymerization initiator blend under conditions effective to polymerize at least about 80% of the monomers in a time of between about 1 minute and about 20 minutes; (d) adding bromine to react with the polymerized styrene under conditions effective to brominate the polymerized styrene to form brominated polymerized monomers, the brominated monomers of which having the following general structure where R is H and x is 3, where the brominated polymerized monomers have an assigned weight average molecular weight (MW) compared with a polystyrene standard as measured by gel permeation chromatography of from about 11,000 to about 60,000; and (e) removing the brominated polymerized monomers from the reaction vessel.