TY - JOUR
T1 - Micelle properties of a dimethylamino- and a trimethylammonium-tipped oxyethylene-oxybutylene diblock copolymer in water
AU - Siddiq, Mohammad
AU - Harrison, Wayne
AU - Tattershall, Carin E.
AU - Budd, Peter M.
PY - 2003/9/15
Y1 - 2003/9/15
N2 - Micelle properties in aqueous solution at temperatures in the range 20-50°C of Me2N(CH2)2OE49B 9 and I-Me3N+(CH2) 2OE49B9, where E represents an oxyethylene unit and B an oxybutylene unit, have been investigated by dynamic and static light scattering, and the results compared with results for EmB n copolymers. For micelles of the dimethylamino-tipped copolymer in aqueous solution, the hydrodynamic radius, rh, was large relative to the thermodynamic radius, rt, suggesting a "soft" micelle. For the trimethylammonium-tipped copolymer, rh decreased and r t increased with increase in temperature, and values of association number, Nw, were low, but increased with increase in temperature, indicating a change from soft micelles at low temperature to small, less swollen micelles at high temperature. High values of thermodynamic volume per molecule, vt/Nw, for the polymer with the charged tip could be attributed to intramicellar charge effects. Addition of salt, to screen the charges, led to a decrease in vt/Nw and an increase in rh, rt and Nw.
AB - Micelle properties in aqueous solution at temperatures in the range 20-50°C of Me2N(CH2)2OE49B 9 and I-Me3N+(CH2) 2OE49B9, where E represents an oxyethylene unit and B an oxybutylene unit, have been investigated by dynamic and static light scattering, and the results compared with results for EmB n copolymers. For micelles of the dimethylamino-tipped copolymer in aqueous solution, the hydrodynamic radius, rh, was large relative to the thermodynamic radius, rt, suggesting a "soft" micelle. For the trimethylammonium-tipped copolymer, rh decreased and r t increased with increase in temperature, and values of association number, Nw, were low, but increased with increase in temperature, indicating a change from soft micelles at low temperature to small, less swollen micelles at high temperature. High values of thermodynamic volume per molecule, vt/Nw, for the polymer with the charged tip could be attributed to intramicellar charge effects. Addition of salt, to screen the charges, led to a decrease in vt/Nw and an increase in rh, rt and Nw.
U2 - 10.1039/b306624j
DO - 10.1039/b306624j
M3 - Article
SN - 1463-9076
VL - 5
SP - 3968
EP - 3972
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 18
ER -