Segment self‐orientational behavior in shape memory polymer thin films probed by Raman spectroscopy

Abstract

Understanding the relationship between the phase separation and domain orientation of segmented block copolymer within thin-film samples is crucial for a complete picture of their physical properties, and hence for the worldwide development of smart materials, and in particular, shape memory textile technology (Hu et al.1–3). We report here on the efficacy of polarized Raman spectroscopy (RS) as a probe of phase separation and average molecular orientation, presenting results for segmented block copolymer thin films with various hard segment contents. A comparison is made with the results of differential scanning calorimetry (DSC). We show in many cases phase separation and domain orientation can be more directly characterized by polarized RS, and that it offers more information on the degree of molecular orientation than conventional thermal measurements. Raman scattering of phase separation in block copolymers has not yet been exploited to provide complementary microscopic information where other techniques are not applicable. The fact that Raman spectrum can be collected in situ, with diffraction limited resolution and chemical specificity makes the technique widely applicable as a noninvasive probe. This study provides clear evidence on the unique molecular ordering in segmented blocked copolymers used in shape memory thin films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007