Abstract
A series of narrow distribution omega-functionalized linear
polyisoprenes were prepared by converting the tertiary amine group of
polyisoprene - obtained by anionic polymerization of isoprene with
3-(dimethylamino)propyl lithium - to the highly polar sulfo-zwitternon
group by treatment with cyclopropane sultone. The dilute solution
properties of these polymers were mainly examined in cyclohexane and
cyclohexane/1-heptanol mixtures. In cyclohexane the sulfo-zwitterion
polymers were highly aggregated. The degree of association generally
decreases with increasing base chain length, due to excluded volume
repulsions of the polymeric tails, except at very low molecular weights
(2 400-4 800) where the different microstructure of these polymers may
play a role. Depending on the molecular weight of the linear precursor,
the aggregates may resemble star polymers or may exhibit a more extended
core morphology. These findings, regarding the shape of the aggregates,
are also supported by melt viscosity measurements and x-ray scattering
studies.