The use of ultra wide pore silica as a catalyst for the hydrogenation of po
lystyrene to give poly(cyclohexylethylene) (PCHE) has facilitated the devel
opment of a dramatically improved process with much milder conditions. The
large pores allow rapid diffusion into and out of-the catalyst, so that the
interior surfaces are also available for reaction. The mild conditions giv
e rise to high-quality PCHE, whose structure is shown in the Figure.