title: Relaxation behavior of poly(methyl methacrylate) at a water interface.
abstract: The relaxation behavior of poly(methyl methacrylate) (PMMA), spin-coated on a silicon wafer, at the water interface was examined by lateral force microscopy as a function of temperature and scanning rate. Even in water, the lateral force peak which was assigned to the segmental motion of PMMA plasticized by water molecules was clearly observed in the temperature domain. The apparent activation energy for the plasticized alpha(a)-relaxation process was much smaller than those for the original alpha(a)-relaxation processes at the intact surface and in the bulk. The depth profile of the glass transition temperature (T(g)) of the PMMA film in water was obtained, showing that T(g) decreases with proximity to the water phase. The T(g) depression observed here was best explained in terms of the water content of the film, rather than a confinement effect.
authors.affiliation: Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Fujii
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nagamura
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D044366:Transition Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D019904:Polymethyl Methacrylate