Sl. Delassus et al., INCORPORATION OF BENZOCYCLOBUTENE INTO POLYSTYRENE ALLOWING POSTPOLYMERIZER CHAIN EXTENSION BRANCHING, Macromolecules, 27(6), 1994, pp. 1307-1312
The introduction of long-chain branching in polystyrene has the potent
ial to improve some of the properties of the polymer. However, our att
empts to make branched polystyrene in continuous free-radical bulk sty
rene polymerization processes has led to gel formation and eventual re
actor fouling. This paper describes a new approach for introducing lon
g-chain branching into polystyrene which would eliminate the reactor f
ouling problem. The approach is to place latent functionality on the p
olymer during polymerization which subsequently reacts to form branche
s upon thermolysis at temperatures > 200-degrees-C. This study focuses
on the benzocyclobutene (BCB) moiety as the latent functionality. BCB
is incorporated into the polymer chain by initiation with BCB functio
nal peroxides, resulting in chain extension/branching upon heating at
240-degrees-C.