T. Kajiyama et al., STUDY OF THE SURFACE GLASS-TRANSITION BEHAVIOR OF AMORPHOUS POLYMER FILM BY SCANNING-FORCE MICROSCOPY AND SURFACE SPECTROSCOPY, Polymer, 39(19), 1998, pp. 4665-4673
The surface molecular motion of amorphous polymeric solids has been di
rectly measured by lateral force microscopic (LFM), scanning viscoelas
ticity microscopic (SVM) and differential X-ray photoelectron spectros
copic (D-XPS) measurements. SVM and LFM measurements revealed that the
molecular motion on the surface of the monodisperse PS film with Mn l
ess than ca. 30 k was fairly active compared with that in the bulk, ma
inly due to the surface segregation of chain end groups. The chain end
group segregation at the air/PS interface was verified by dynamic sec
ondary ion mass spectroscopic depth profiling of the proton and deuter
ium ion for end-labelled PS film. These results suggest that surface T
-g is depressed because of an increase in free volume near the surface
region, induced by the preferential surface localization of chain end
groups. D-XPS was utilized for the characterization of surface molecu
lar motion of symmetric poly(styrene-block-methyl methacrylate) dibloc
k copolymer [P(St-b-MMA)] films. It was confirmed by D-XPS that the su
rface molecular motion of the PS component in [P(St-b-MMA)] diblock co
polymer films was gradually activated with decreasing depth from the a
ir/polymer interface. (C) 1998 Elsevier Science Ltd. All rights reserv
ed.