Hydrogenated Polystyrene Preparation and Properties

Corporate Research and Development, The Dow Chemical Company, Midland, Ml, USA 

The synthesis and characterization of the hydrogenation product of polystyrene (PS), poly(cyclohexylethylene) (PCHE), have been the subject of persistent research efforts. The earliest published report on this material dates to 1929, with new work appearing steadily up to the present. The primary motivation for saturating the phenyl rings in polystyrene is the potential to improve the stability of polystyrene with respect to oxidative and radiation-induced degradation. It has now also been established that the hydrogenation of polystyrene leads to a substantial increase in the glass transition temperature (Tg). 

An improved understanding of the relationship between repeat unit structure and physical properties has also provided motivation the hydrogenation process allows for the direct study of the influence of the new cyclohexyl side substituent in comparison with the phenyl group present in the starting material. At the time of this writing, PCHE is not an item of commerce. A variety of applications have been proposed, however, that would take advantage of the properties of this material. 

Two distinct synthetic strategies have successfully been employed to prepare high molecular weight PCHE. The most extensively utilized route, the hydrogenation 

Modern Styrenic Polymers Polystyrene and Styrenk Copolymers. Edited by J. Scheirs and D. B. Priddy r 2003 John Wiley Sons Ltd 

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In heterogeneous catalysts, the tailored and pillared cavity is an essential property as it enables the movement of reactants to inner catalytic sites. The mass transfer of reactants and products inside the pores is mainly influenced by the interaction of the internal walls of the channel with organic molecules, and can consequently be controlled by the difference in polarities. To ensure such properties, anchored ruthenium hybrid zirconium phosphate-phosphonates coated with hydrophobic linear double-stranded polystyrene over the inner surface of the Zr layers were prepared by the first complexation of Ru and then molding of inorganic backbone method, and used as the catalyst in the ATH of o-, m- and p-substituted acetophenones (Fig. 42) [121]. This catalyst showed good catalytic activity and enantioselectivity (73.6-95.6 % ees) in the aqueous reduction with FA-TEA as the hydrogen donor, and could retain its catalytic properties after five runs in the case of acetophenone. 

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