The associative properties of Me2N (CH2)(2)OE58B7 and I-Me3N+(CH2)(2)OE58B7 in aqueous solution in the temperature range of 20-50 degrees C have been investigated by dynamic and static laser light scattering. Here E represents an oxyethylene unit and B an oxybutylene unit. The results obtained were compared with results for EmBn analog. Our result shows that for micelles of dimethylamino-tipped, the hydrodynamic radius, was large as compared with the thermodynamic radius r(t), suggesting a soft micelle. For the trimethylammonium-tipped copolymer, r(h) decreases and r(t) increase with the increase in temperature. Also the values of association number, N-w, were low but increase with increase in temperature, indicating a change from soft micelle at low temperature to small, less swollen micelles at high temperature. The high values of thermodynamic volume per molecule, r(t)/N-w, for a polymer with charged tip could be attributed to intermicellar charge effect. The effect of salt on various micellar parameters has also been discussed. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012