Syndiotactic Polystyrene epsilon Cocrystals With n-Alkanes: Guest Uptake and Crystal Structure

s-PS epsilon-clathrates with different n-alkanes, ranging from n-hexane to n-dodecane, have been obtained for the first time and their structure has been investigated by means of X-ray diffraction, FT-IR spectroscopy, and molecular mechanics calculations. The diffraction data of all the s-PS/n-alkane epsilon-clathrates are in agreement with the orthorhombic unit cell with axes a = 1.62 nm, b = 2.20 nm, and c = 0.79 nm and the space group Pbcn, proposed for the nanoporous epsilon form, indicating that the crystal packing of the chains in the clathrate forms remains substantially unaltered independently of the length of the n-alkane. Molecular mechanic calculations provided conclusions that the n-alkanes' guest, independent of their length, are arranged in the channels in fully trans-planar conformation with their main molecular axis almost parallel to the axis of the cavity. The possibility of having n-alkane guest with a bent conformation in the channels was also ruled out. A detailed structural study was carried out for the cocrystalline form containing n-octane. Supplemental materials are available for this article. Go to the publisher's online edition of Soft Materials to view the free supplemental file.