Water-tolerant catalyst systems for the bulk cationic polymerization of para-methylstyrene and indene

Water-tolerant catalyst systems have been investigated for the cationic oligomerization of technical-grade p-methylstyrene and indene, for the production of industrially relevant aromatic resins. Systems based on 1-p-tolylethanol and 1-indanol (ROH) as initiators, in association with Cu(OTf)2, Bi(OTf)3 (OTf = triflate) and B(C6F5)3 as co-initiators/catalysts, show interesting productivities at 60 °C under air, with as low as 0.2–1.0 mol% catalyst loading. Most of the reactions are not controlled in terms of molecular weights of the products, except for indene oligomerization by the borane catalyst where experimental Mn values match well the theoretical values, as determined by the amount of added initiator over a 5-fold range (with 2–10 mol% vs. monomer). The ROH/tris(pentafluorophenyl)borane system offers the best compromise in terms of productivity and control over the molecular weights of the oligomers, which can be manipulated by the amount of initiator and reaction temperature.

As low as 0.2–1.0 mol% of Cu(OTf)2, Bi(OTf)3 or B(C6F5)3, in association with alcohols, are effective catalysts for the cationic oligomerization of technical-grade p-methylstyrene and indene. The ROH/B(C6F5)3 system offers the best compromise in terms of productivity and control over the molecular weights, which can be manipulated in the case of indene by the amount of initiator and reaction temperature.Figure optionsDownload as PowerPoint slide