Studies in ring-opening polymerization—XII. The ring-opening polymerization of oxetane to living polymers using a porphinato-aluminium catalyst

Metalloporphyrins as Initiators for Living and Immortal Polymerizations

“…Amass et al . have reported that oxetane is polymerizable with a chloroaluminum porphyrin ( 1c ) alone as initiator at an elevated temperature such as 60 °C . We have confirmed that the initiation of polymerization takes place even at room temperature in the absence of 48 , whereas the subsequent propagation does not occur.…”

“…In addition to epoxides ( 11 ), heterocyclic monomers such as lactones with four-, six-, and seven-membered rings (β-, γ-, and ε-lactones) ( 13 − 15 ) − and lactide ( 16 ) are polymerized by aluminum porphyrin initiators to give narrow MWD polyesters (Table ). The living polymerizations of a cyclic carbonate ( 17 ), cyclic siloxanes ( 19 ), and a four-membered cyclic ether ( 12 , oxetane) with aluminum porphyrins ( 1 ) as initiators have been reported by Höcker, Yoshinaga, and Amass, respectively. In the presence of ammonium or phosphonium salts, 1c brings about the living alternating copolymerizations of epoxides with carbon dioxide or phthalic anhydride, affording polycarbonates or polyesters , with narrow MWD.…”

Controlled Coordinate Anionic Polymerization of Oxetane by Novel Initiating Systems: Onium Salts/Bulky Organoaluminum Diphenolates

“…As an extension of the above-mentioned “high-speed living anionic polymerization”, we have recently succeeded in the living coordinate anionic polymerization of oxetane by using the system consisting of chloroaluminum porphyrin and 1 . Oxetane has long been categorized in the monomer which is only cationically polymerizable, because of its high Lewis basicity and therefore low susceptibility to nucleophiles. , In the present paper, we report more simple and versatile initiating systems, consisting of quaternary onium halides and bulky organoaluminum diphenolates, for controlled coordinate anionic polymerization of oxetane, and also provide results of crystallographic and NMR studies on the initiating systems.…”

Immortal SET–LRP mediated by Cu(0) wire

“…As defined by its inventors,37, 38 “immortal polymerization is the polymerization that gives polymers with a narrow molecular weight distribution, even in the presence of a chain transfer reaction, because of its reversibility, which leads to the revival of the polymers once dead, that is, the immortal nature of the polymers.”37 Immortal polymerization was originally developed for the ionic ring‐opening polymerization (ROP) of epoxide/epsulfide,39–44 lactones,45–52 lactides,53–57 and cyclic carbonates58–61 in the presence of chain‐transfer agents, typically alcohols. In this case, to conduct a successful immortal ROP, a rapid and reversible exchange between metal alkoxide and alcohol is required.…”