A COMPARISON BETWEEN HYDROPHOBICALLY END-GAPPED POLY(ETHYLENE OXIDE) WITH ETHER AND URETHANE BONDS

Two models of HEUR (hydrophobically modified ethylene oxide urethane) associative polymers (AP) are compared. The two polymers are polyethyl eneoxides simply end-capped with dodecyl groups, one through an ether bond H25C12-O-(CH2CH2O)(304)-C12H25 (AP14, M-w = 13,700) and the other through an urethane bond H25C12-NHCOO-(CH2CH2O)(304)-CONH-C12H25 (AP1 4-NCO, M-w is about the same as for AP14). The results indicate that t his subtle difference in polymer architecture dramatically influences the initial association and the clouding of the polymer in water, so t hat AP14NCO starts to aggregate earlier but has a higher clouding temp erature. However, at more elevated polymer contents (above 2-3 wt%) th e differences in solution behavior and transport dynamics between the two polymers seems less significant. These conclusions are drawn throu gh fluorescence, dynamic light scattering, NMR self-diffusion, turbidi metry, and viscosity measurements. (C) 1997 Academic Press.