Raman spectroscopic study of the formation of polyacetylene within zeolite channels

Abstract

Raman spectroscopy has been employed to study the polymerisation of acetylene on various zeolite substrates. Sodium mordenite (NaM) was determined to be an inefficient catalyst. The majority of the acetylene in this system was found to be in the form of monomers which were bound in a ‘side-on’ fashion to cation sites within the main mordenite channel. In contrast, caesium mordenite (CsM) samples facilitated the growth of trans-polyacetylene to a far greater degree. Furthermore, the use of elevated pressures of acetylene was also found to be beneficial to polymer formation. Finally, pretreatment of CsM with CCl₄ enhanced the rate of polymer growth substantially. An explanation of these effects is given.