Synthesis and viscosity of hydrophobically modified polymers containing dendritic segments

The cycloterpolymerizations of a newly synthesized dendritic quadruple-tailed hydrophobic diallylammonium chloride with the hydrophilic monomer N,N-diallyl-N-carboethoxymethylammonium chloride and sulfur dioxide afforded a series of water-soluble cationic polyelectrolytes (CPEs) containing various proportions (0-1 mol %) of the hydrophobe. At a shear rate of 0.36 s^-1 at 30°C, salt-free water solutions of the CPEs (4 g/dL) containing 0, 0.35, 0.53, 0.65, and 0.93 mol % of the hydrophobe had apparent viscosity values of 140, 1200, 180,000, 308,000, and 858,000 cps, respectively. The study clearly demonstrated an increase in the viscosity values with increasing incorporation of the hydrophobes. The CPEs on acidic hydrolysis of the pendant ester groups gave corresponding pH-responsive cationic acid salts, which upon treatment with NaOH, were converted to the polybetaines (PBs), anionic polyelectrolytes (APEs), and PB/APEs containing various proportions of PB and APE fractions in the polymer chain. The effects of charge type and charge density on the polymer chain were investigated. Polymer surfactant interactions were investigated with the cationic surfactant cetyltrimethyl-ammonium bromide; a considerable increase in the viscosity values of the CPE was observed in the presence of the surfactant. The superior viscosity behavior for the polymers containing the quadruple-tailed hydrophobe was attributed to the blocky nature of the comonomer.