title: Detection of surface mobility of poly (2, 3, 4, 5, 6-pentafluorostyrene) films by in situ variable-temperature ToF-SIMS and contact angle measurements.
abstract: Poly (2, 3, 4, 5, 6-pentafluorostyrene) (5FPS) was prepared by bulk radical polymerization. The spin-cast films of this polymer were analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) at various temperatures ranging from room temperature to 120°C. Principal component analysis (PCA) of the ToF-SIMS data revealed a transition temperature (T(T)) at which the surface structure of 5FPS was rearranged. A comparison between the results of the PCA of ToF-SIMS spectra obtained on 5FPS and polystyrene (PS) indicate that the pendant groups of 5FPS and PS moved in exactly opposite directions as the temperature increased. More pendant groups of 5FPS and PS migrated from the bulk to the surface and verse versa, respectively, as the temperature increased. These results clearly support the view that the abrupt changes in the normalized principal component 1 value was caused by the surface reorientation of the polymers and not by a change in the ion fragmentation mechanism at temperatures above the T(T). Contact angle measurement, which is another extremely surface sensitive technique, was used to monitor the change in the surface tension as a function of temperature. A clear T(T) was determined by the contact angle measurements. The T(T) values determined by contact angle measurements and ToF-SIMS were very similar.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
authors.forename: Yi
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Nano and Advanced Materials Institute, Hong Kong Science Park, Shatin, New Territories, Hong Kong.
authors.forename: Yiu-Ting R
authors.initials: YT
authors.lastname: Lau
authors.affiliation: Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong; Materials Characterization and Preparation Facility, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
authors.forename: Lu-Tao
authors.initials: LT
authors.lastname: Weng
authors.affiliation: Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong; Advanced Engineering Materials Facility, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
authors.forename: Kai-Mo
authors.initials: KM
authors.lastname: Ng
authors.affiliation: Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong; Division of Environment, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong. Electronic address: kecmchan@ust.hk.
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Chan
keywords: Contact angles; Poly (2, 3, 4, 5, 6-pentafluorostyrene); Principal component analysis; Surface reorientation; Thin films; ToF-SIMS