Surface segregation behavior in miscible polymer blend thin film of poly(4-trimethylsilylstyrene)(PT)/polyisoprene (PI) was investigated as a function of temperatures on the basis of contact angle and neutron reflectivity measurements. For all temperatures employed, PT, which is a lower surface free energy component, is segregated at the surface of the blend film due to the requirement for minimizing the total free energy of the system. A concentration profile near the blend film surface is in good agreement with the mean-field prediction at 373 K and 393 K, being much lower than the lower critical solution temperature (LCST) for the blend in bulk. It was confirmed that decay length, ζ, and surface excess amount. z*. increase with increasing temperature. On the other hand, a concentration fluctuation in the internal region becomes remarkable at 453 K, even below the LCST in bulk. Thus, it is concluded that a concentration fluctuation in PT/PI blend thin film below the LCST is induced by the surface segregation of PT component in blend thin film.
All Science Journal Classification (ASJC) codes
- Polymers and Plastics
- Materials Chemistry