Order to disorder transition at the polymer-air interface for hydrophobic octadecyl side chain copolymers. Gautam, Keshav S.; Dhinojwala, Ali. Department of Polymer Science, University of Akron, Akron, OH, USA. Mater. Res. Soc. Symp. Proc. (2001), 661(Filled and Nanocomposite Polymer Materials), KK6.3/1-KK6.3/6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:331849 AN 2001:621799 CAPLUS

Mol. orientation of octadecyl alkyl side chains at the poly(vinyl octadecyl carbamate-co-vinyl acetate) polymer-air interface has been studied using surface sensitive sum frequency generation (SFG) spectroscopy. At 28°C, below the side chain cryst. transition temp., the SFG spectra show strong Me vibrations indicating ordered alkyl side chains at the polymer-air interface. In the liq. state (98°C), the SFG spectra show higher contributions from the methylene vibrations indicating higher gauche defects at the interface. This surface order to disorder transition is gradual and spans over a broad temp. range (50-90°C), where the bulk is in the smectic liq. cryst. state.