title: Distribution of glass transition temperatures Tg in polystyrene thin films as revealed by low-energy muon spin relaxation: A comparison with neutron reflectivity results.
abstract: In a previous paper [Phys. Rev. E 83, 021801 (2011)] we performed neutron reflectivity (NR) measurements on a five-layer polystyrene (PS) thin film consisting of alternatively stacked deuterated polystyrene (dPS) and hydrogenated polystyrene (hPS) layers (dPS/hPS/dPS/hPS/dPS, ∼100 nm thick) on a Si substrate to reveal the distribution of Tg along the depth direction. Information on the Tg distribution is very useful to understand the interesting but unusual properties of polymer thin films. However, one problem that we have to clarify is if there are effects of deuterium labeling on Tg or not. To tackle the problem we performed low-energy muon spin relaxation (μSR) measurements on the above-mentioned deuterium-labeled five-layer PS thin film as well as dPS and hPS single-layer thin films ∼100 nm thick as a function of muon implantation energy. It was found that the deuterium labeling had no significant effects on the Tg distribution, guaranteeing that we can safely discuss the unusual thin film properties based on the Tg distribution revealed by NR on the deuterium-labeled thin films. In addition, the μSR result suggested that the higher Tg near the Si substrate is due to the strong orientation of phenyl rings.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan.
authors.forename: Toshiji
authors.initials: T
authors.lastname: Kanaya
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ogawa
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Kishimoto
authors.affiliation: Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka-fu 590-0494, Japan.
authors.forename: Rintaro
authors.initials: R
authors.lastname: Inoue
authors.affiliation: Laboratory for Muon-Spin Spectroscopy, Swiss Muon Source SµS, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Suter
authors.affiliation: Laboratory for Muon-Spin Spectroscopy, Swiss Muon Source SµS, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Prokscha