Vacuum ultraviolet (VUV) transmission spectra show a clear polarization effect in pi electronic transition in spin coated atactic polystyrene (aPS) films of thickness below 4Rg, where Rg (~20.4nm) is the radius of gyration of the polymer. This transition associated with pendant benzene rings in polystyrene. The polarization effect clearly indicates pendant benzene ring alignment on a macroscopic scale. Study of core electron (1s) transition through near edge x-ray absorption fine structure (NEXAFS) spectroscopy confirms the ordering and shows that the rings are oriented towards out-of-plane direction with a tilt angle ~63 degree with the sample plane, which is consistent with the observed in-plane (sample surface) VUV polarization. These results indicate the transition of a common polymer, like polystyrene, inherently disordered in the bulk, to an orientationally ordered phase under a certain degree of confinement.
@article{arxiv.0709.2528,
title = {Confinement Induced Polarization effects in Valence and Inner-shell Spectra of Atactic Polystyrene},
author = {Sudeshna Chattopadhyay and A. Datta and A. Giglia and N. Mahne and S. Nannarone},
journal= {arXiv preprint arXiv:0709.2528},
year = {2007}
}