An imidazole-based organocatalyst designed for bulk polymerization of lactide isomers: inspiration from Nature

Abstract

The design of an imidazole-based salt by enzyme-mimicking allowed controlling the ring-opening polymerization of L- and D-LA monomers in bulk. Kinetic study supports a bifunctional activation process only slightly different from the one occurring in Nature.

Organocatalyzed ring‐opening polymerization of cyclic butylene terephthalate oligomers

“…As recently reviewed by Taton et al, a large variety of organic compounds have been employed to catalyze polymerization reactions, either in bulk or in solution. When conducted in bulk, these polymerizations were usually performed at relatively low temperatures (<150 °C) due to the low melting point of the monomers employed . Because of the high melting temperature of CBT, bulk polymerization of CBT has to be carried out at temperatures of 180 °C or higher .…”

“…At the high temperature employed for the ROP of CBT, one may assume that these interactions are disfavored, resulting in low monomer activation and thus in low monomer conversion. On the other hand, TBD and DBU have been reported to follow nucleophilic/basic pathways that can occur even at relatively high temperatures and lead either to monomer activated mechanism, chain‐end activated mechanism or a combination of both mechanisms …”

Low Temperature Ring‐Opening Polymerization of Diglycolide Using Organocatalysts with PEG as Macroinitiator

“…Therefore, it appeared interesting to test whether organocatalyzed ring‐opening polymerizations (ROP) provide an alternate route to PGA. Several groups of organic substances are known to show catalytic activity toward ring‐opening reactions of cyclic molecules, e.g., N ‐heterocyclic carbenes, guanidines, and amidines . 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU), 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN), and 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) as representatives of organocatalysts for ROP are considered as “super base” catalysts.…”

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

“…Although there are some reports about the bulk ROP of cyclic esters using organocatalysts, the advantages of bulk conditions have not been investigated in detail. [12][13][14]25,26,37,[60][61][62][63][64][65][66][67][68][69][70][71][72][73] We now describe the organophosphate-catalyzed bulk ROP of various cyclic esters, such as ε-CL,…”

“…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). 7,[20][21][22][23][24]26 In addition, the bifunctional catalytic system possessing two activation sites for the monomer and propagating chain end also turned out to be effective for the ROP of ε-caprolactone (ε-CL) and LA. [27][28][29][30][31][32][33][34][35][36][37] For example, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a bifunctional catalytic system promotes the ROP of the ε-CL, whereas DBU is ineffective, 20 and the MSA/DMAP bifunctional 4 catalytic system promotes the ROP of the LA, whereas MSA alone does not work.…”