Kinetic Study of the Ring-Opening Metathesis Polymerization of Ionically Functionalized Cyclooctatetraenes

The ring-opening metathesis polymerizations of alkylammonium and sulfonate functionalized cyclooctatetraenes (RCOT, R = CH 2 CH 2 SO 3 TMA or CH 2 CH 2 NMe 3 OTf, OTf = CF 3 SO 3 -, TMA = Me 4 N + ) with the well-defined tungsten catalyst W CH( o -C 6 H 4 OMe)(NC 6 H 5 )[OCCH 3 (CF 3 ) 2 ] 2 (THF) (THF = tetrahydrofuran) were investigated. The polymerizations exhibited first-order decay in monomer concentration and slow initiation relative to propagation, and for COTCH 2 CH 2 SO 3 TMA where studies were possible, molecular weights largely independent of the extent of the reaction and initial reaction conditions. The central kinetic feature was the observation of a pseudo-first-order rate constant inversely proportional to the initial monomer concentration, suggesting some form of inhibition. Furthermore, the polymerization of COTCH 2 CH 2 NMe 3 OTf is inhibited by the addition of TBAOTf (TBA = Bu 4 N + ). The apparent inhibition is discussed in terms of the potential for ion pairing or anion coordination to the catalyst center.