Effect end group chemistry on surface molecular motion of monodisperse polystyrene films

The surface molecular motion of monodisperse polystyrene PS) with various c hain end groups was investigated on the basis of temperature-dependent scan ning viscoelasticity microscope (TDSVM). The surface glass transition tempe ratures, T(g)(s)s for the proton-terminated PS (PS-H) films with number-ave rage molecular weight, M-n of 4.9k - 1,450k measured by TDSVM measurement w ere smaller than those for the bulk one, with corresponding M(n)s, and the T(g)(s)s for M-n smaller than ca. 50k were lower than room temperature (293 K). In the case of M-n = ca. 50k, the T(g)(s)s for the alpha,omega -diamin o-terminated PS (alpha,omega -PS(NH2)(2)) and alpha,omega -dicarboxy-termin ated PS (alpha,omega -PS(COOH)(2)) films were higher than that of the PS-H film. On the other hand, the (TgS)-S-s for the alpha,omega -perfluoroalkyls ilyl-terminated PS (alpha,omega -PS(SiC2C6F)(2)) film with the same M-n was much lower than those for the PS films with all other chain ends. The chan ge of T-g(s) for the PS film with various chain end groups can be explained in terms of the depth distribution of chain end groups at the surface regi on.