Organocatalytic ring-opening polymerization of l-lactide in bulk: A long standing challenge

Abstract

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Solvent‐free ring‐opening polymerization of lactones with hydrogen‐bonding bisurea catalyst

“…In coordination with the appropriate tertiary amines as HBAs, HBDs can synergistically catalyze ROP through the mechanism that HBD activates the carbonyl of monomers and HBA activates initiators or the propagating chain end. Moreover, conducting ROP under solvent‐free conditions is an attractive strategy for the industrial‐scale polymerizations as well as the laboratory‐scale preparation of highly pure polyesters …”

“…Moreover, conducting ROP under solvent-free conditions is an attractive strategy for the industrial-scale polymerizations as well as the laboratory-scale preparation of highly pure polyesters. 30,[34][35][36][37][38] Based on the previous work, the multi(thio)urea catalysts studied by Kiesewetter are connected by flexible groups, and the activation mechanism is activated-urea or dual-urea activation that all between intramolecular hydrogen bonding. 27,28,39 We put forward an assumption that the catalytic performances of HBD with essential rigid groups enhance the activity by intermolecular hydrogen bonding.…”

Food Sweetener Saccharin in Binary Organocatalyst for Bulk Ring‐Opening Polymerization of Lactide

“…The strategic evolution of organocatalytic ring-opening polymerization of cyclic esters in the last seventeen years [6,18] received tremendous success in new catalyst design and novel polymerization discovery. In the current endeavor of translational development toward industrially viable organopolymerizations, [21,39] major challenges to as well as ideal attributes of an organocatalyst for ROPs should be bulk polymerization by readily available catalyst viable at elevated temperatures without transesterification and safe remained in the polymeric materials. To meet these ends, we proposed pyridinium saccharinate binary organocatalyst that would follow Feijen's five-point principles [23] for industrially feasible ROP of lactide.…”

“…Catalysis in sustainable polymers [15] dictates ROPs of LA by variety of catalytic modes that employed transition metal complexes, [16] enzymes, [17] and organic small molecules. [6,18] Our interest in organocatalyzed ROPs [19] of biobased heterocyclic monomers [20] promoted us to consider the challenges of organocatalysts in ROPs [21] towards potential commercial developments. A prominent industrialized process of ROP of LA catalyzed/ initiated by SnOct 2 [22] enjoyed some features of metal complex catalysts for PLA production that were later clarified by Feijen as industrially attractive in five aspects.…”

Extending the Scope of Benign and Thermally Stable Organocatalysts: Application of Dibenzoylmethane for the Bulk Copolymerization of l‐Lactide and ɛ‐Caprolactone

“…In contrast, attempt at copolymerizing LA and CL by BPA has led to the incorporation of a limited fraction of LA (8 mol %) into the final copolymer, suggesting a r CL higher than r LA in these peculiar conditions. Importantly, it has to be noticed that one other major drawback of the organocatalysts used in the ROP of l ‐LA is their poor thermostability …”