Poly(aminophosphazene)s and Protophosphatranes Mimic Classical Strong Anionic Base Catalysts in the Anionic Ring-Opening Polymerization of Lactams

Abstract

Linear very high molecular weight polyamides, such as nylons 6, 7 and 66, have been prepared via the rapid ring-opening polymerization (ROP) of their respective lactams catalyzed by super nonionic poly(aminophosphazene) and protophosphatrane bases. The super nonionic poly(aminophosphazene) bases appear to mimic catalysis by conventional anionic catalysts, but with the added advantage of the toleration of some degree of moisture. Multinuclear liquid and solid-state NMR experiments were used to probe the structure and proton transfer chemistry of P4-t-Bu, one of the most effective lactam ROP poly(aminophosphazene) bases. 31P magic-angle spinning (MAS) results showed the room-temperature structure of P4-t-Bu to be asymmetric and nonprotonated. Variable-temperature 31P MAS NMR experiments on mixtures of P4-t-Bu and ε-caprolactam demonstrated the proton transfer chemistry relevant for ROP at elevated temperature. This was confirmed by 13C MAS NMR observation of the ε-caprolactam anion in a cross-polarization experiment.

Synthesis, characterization, and photoresponsive behavior of new azobenzene‐containing polyethers

“…t ‐Bu‐P 4 is an extremely strong neutral nitrogenated base; however, because of its high volume, it also has a weak nucleophilic character. As a consequence of these features, this compound, together with other similar ones of the same family, has been widely used both in organic synthesis35–37 and in the polymerization of different monomers 38–40. The use of t ‐Bu‐P 4 also exhibits several advantages: it is commercially available as hexane solution and can be easily handled and measured out; moreover, it is relatively stable to temperature and air and it does not require strictly careful working conditions, differently from other bases.…”

Organophosphate-catalyzed bulk ring-opening polymerization as an environmentally benign route leading to block copolyesters, end-functionalized polyesters, and polyester-based polyurethane

“…In order to avoid metal contamination without any special purification steps, the organocatalytic approach has emerged as a powerful metal-free polymerization process in recent years. 7 Considerable effort has been directed toward the evaluation of various types of both organic acids/bases for the ROP of cyclic esters, 7-37 cyclic carbonates, [38][39][40][41][42][43] epoxides, [44][45][46][47] lactams, 48 cyclic (carbo)siloxanes, 49 cyclic phosphates, [50][51][52][53][54] etc. Regarding the ROP of cyclic esters, organic Brønsted acids, e.g., methane sulfonic acid (MSA) and triflimide, were found to be suited for the polymerization of lactones, [8][9][10][11][12][13][14][15][16][17][18][19] whereas organic bases, e.g., 1,8-diazadicyclo [5.4.0]undec-7-ene (DBU) and 4-dimethylaminopyridine (DMAP), were effective for the ROP of the lactide (LA).…”

Synthesis of Poly[(ethylene carbonate)‐co‐(ethylene oxide)] Copolymer by Phosphazene‐Catalyzed ROP

“…[20][21][22][23][24] Recently, such catalysts have been used in ring-opening polymerizations of ε -lactams, [ 25 ] cyclopropane-1,1-dicarboxylates, [ 26 ] and β -lactones. [ 27 , 28 ] In the present work, we report the ring-opening polymerization of 1,3-dioxolan-2-one with 1-tert -butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)-phosphoranylidenamino]-2 Λ 5, Λ 5-catenadiphosphazene ( t-BuP 4 ) as the catalyst.…”