Process for controlling the molecular weight of polymers of bromostyrenes

1. A process to control the molecular weight of bromostyrene 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) ar-bromostyrene monomers having the following general structure

 where R is H and x is 3, where the polymers 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;

(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; and

(d) removing the polymerized bromostyrenes from the reaction vessel.

2. The process of claim 1 wherein the bromostyrene polymers retain at least 88% of their mass after 20 minutes and at least 85% of their mass after 30 minutes when a 10 mg specimen is held at 330° C. under a nitrogen atmosphere.

3. The process of claim 2 wherein the bromostyrene polymers have an assigned weight average molecular weight compared with a polystyrene standard as measured by gel permeation chromatography of from about 15,000 to about 20,000.

4. The process of claim 1 wherein the bromostyrene polymers further comprise residues of α-methyl styrene dimer.