ASSOCIATION BEHAVIOR OF LINEAR OMEGA-FUNCTIONALIZED POLYSTYRENES IN DILUTE-SOLUTIONS

Linear polystyrenes with dimethylamino end groups were prepared by ani onic polymerization, using 3-(dimethylamino)propyllithium as initiator and high vacuum techniques. The amino group was transformed to a sulf ozwitterionic moiety by reaction with 1,3-propanesultone. The dilute s olution properties were studied by means of membrane osmometry (MO), l ow-angle laser light scattering (LALLS) and viscometry in solvents wit h different polarity. The amine-capped polymers, studied by LALLS in t etrahydrofuran (THF), toluene and CCl4 show no evidence of association . In contrast, the zwitterionic samples exhibited a relatively strong association in CCl4 (relative permittivity epsilon = 2.24), weak in TH F (epsilon = 7.4), and intermediate in toluene (epsilon = 2.4). The as sociation numbers were lower than those found for linear polyisoprenes and polybutadienes with the same end groups. Viscosity measurements s upported the results drawn from LALLS. The results provide strong evid ence that the micelles behave hydrodynamically as star polymers. The a ssociation behavior is best described by the linear head packing model .