Aggregation behavior of X-shaped branched block copolymers at the air/water interface: effect of block sequence and temperature

The aggregation behaviors of X-shaped block copolymers, Tetronic 1107 and Tetronic 90R4 with a sequential and reverse architecture, at the air/water interface were studied. The effects of block sequence, concentration, and temperature were investigated by equilibrium surface tension, surface dilational viscoelasticity, and surface tension relaxation measurements. The conformations of Tetronic 1107 and Tetronic 90R4 are different at the air/water interface. The possible adsorption model of Tetronic 1107 is brush and that of Tetronic 90R4 is invert umbrella. With the increase of temperature, the dilational modulus of Tetronic 1107 solutions decreases, while that of Tetronic 90R4 solutions increases. The mechanisms of the temperature which effects on the conformational transition of Tetronic 1107 and Tetronic 90R4 were discussed in detail. Furthermore, the thermodynamic parameters for the micellization of Tetronic 1107 and Tetronic 90R4 were compared at different temperatures.