DILUTE-SOLUTION BEHAVIOR OF CARBOXYLATOBETAINE END-CAPPED POLYISOPRENES

The synthesis and characterization of polyisoprene bearing carboxylato betaines of various intercharge lengths, either at one or at both ends of the polymer chain, are described. Peculiar properties such as asso ciative behaviour may be expected due to their original functionalizat ion. These materials are prepared by anionic polymerization of isopren e and deactivation with dimethylaminopropyl chloride, followed by reac tion with bromoalkyl ethyl carboxylic esters and subsequent hydrolysis . Highly viscous solutions are obtained when the polymers are dissolve d in solvents of low polarity. Average aggregation numbers are calcula ted from the viscosity results, which depend on the molecular weight o f the aminated precursor polymer as well as the intercharge length of the zwitterionic groups. The effects of temperature and polar additive s are also considered.