Cationic polymerization of isobutyl vinyl ether using alcohols both as cationogen and catalyst‐modifying reagent: Effect of Lewis acids and alcohols on living nature

Direct synthesis of highly reactive polyisobutylenes via cationic polymerization of isobutylene co‐initiated with TiCl4 in nonpolar hydrocarbon media

“…Moreover, both the monomer conversion and [PIB] in polymerization system increased gradually from <6.2 to near 60% with increasing molar ratios of i AmOH/TiCl 4 or i PrOH/TiCl 4 from 0 to 0.4. These experimental results further prove the protic initiation from alcohol, i.e., i AmOH or i PrOH, which is similar to the report by Aoshima . As shown in Figure , the desired PIBs with lower molecular weight and narrower molecular weight distribution could be prepared at higher concentration of alcohol, which is attributed to the increase in the initiation from alcohol and concentration of initiating species.…”

“…It is worth mentioning that 100% of polymer yield could be obtained by using iAmOH/TiCl 4 ini-tiating system in the absence of TMPCl at [iAmOH] 5 28 mmolÁL 21 , suggesting that the protic initiation from iAmOH did occur under these conditions. This experimental result is similar to the report of living cationic polymerization of vinyl ether with methanol/metal chloride initiating systems by Aoshima, 83,84 but quite different from that in the FeCl 3 -coinitiated polymerizations in our previous works. 19,62 Polymerization temperature is a critical factor for initiation, propagation, and termination in the cationic polymerization of IB.…”

“…These experimental results further prove the protic initiation from alcohol, i.e., iAmOH or iPrOH, which is similar to the report by Aoshima. 83,84 As shown in Figure 12, the desired PIBs with lower molecular weight and narrower molecular weight distribution could be prepared at higher concentration of alcohol, which is attributed to the increase in the initiation from alcohol and concentration of initiating species. The M n of the resulting PIB was 1200 gÁmol 21 and M w /M n was 1.54 when iAmOH/ TiCl 4 5 0.4 (molar ratio).…”

In situ and readily prepared metal catalysts and initiators for living cationic polymerization of isobutyl vinyl ether: dual-purpose salphen as a ligand framework for ZrCl4and an initiating proton source

“…9 Among various combinations, alcohol or acetylacetone with an appropriate metal halide permitted in situ ligand exchange, generating a real catalytic species inducing living polymerization. 10,11 These results encouraged us to pursue the goal of designing metal complex catalysts for precise polymer synthesis using cationic polymerization. Despite the potency of metal complex catalysts, catalyst design using various ligands has been limited in cationic polymerization, 9,12,13 although ligand design or in situ complex formation was demonstrated to be effective for achieving the stereoselective cationic polymerization of alkyl vinyl ethers 14 or styrene derivatives.…”

“…In addition, our previous study showed that an alkoxy group on certain Lewis acid catalysts dissociates from the central metal to react with the propagating carbocation. 10 Hence, catalyst design to date in this field has focused on relatively simple compounds containing alkoxy or phenoxy groups. 10,11,14,20 To circumvent the abovementioned problems, the use of a Schiff base ligand would be effective because the chelating effect of the ligand is expected to suppress any ligand exchange reactions that might lead to the deactivation of the polymerization.…”