Update and challenges in organo-mediated polymerization reactions

Abstract

International audienceOrganocatalysis has become a very powerful tool for precision macromolecular chemistry, as judged by the number of articles published in this field in the past decade. A variety of small organic molecules, including Bronsted/Lewis bases and acids, based on amines, phosphines or carbenes, but also on bi-component systems, have been employed as a means to catalyze the polymerization of miscellaneous monomers. Not only can organocatalysts be employed to promote the ring-opening polymerization of various heterocyclics (e.g. lactones, lactide, cyclic carbonates, epoxides, lactams, cyclocarbosiloxanes), but some of them also allow activating vinylic monomers such as (meth)acrylics, or triggering the step growth polymerization of monomers such as diisocyanates and diols for polyurethane synthesis. The reduced toxicity of organocatalysts in comparison to their metallic counterparts is also driving their development in some sensitive applications, such as biomedical or microelectronics. Overall, organocatalysts display specific monomer activation modes, thereby providing a unique opportunity to control the polymerization of various functional monomers, under mild conditions. This review article focuses on advances of the past 4 years (>150 publications) in polymerization reactions utilizing small organic molecules either as direct initiators or as true catalysts, with a special emphasis on monomer activation modes, as well as polymerization mechanism aspects

Bifunctional Squaramides as Organocatalysts for Lactide Polymerization: Catalytic Performance and Comparison with Monofunctional Analogues

“…Overall, the kinetic and characterization data on l ‐LA ROP catalysis by bifunctional aminosquaramides 1 – 3 (which include the comparison with the monofunctional analogues 4 and 5 ) hint clearly at a ROP process that occurs through a cooperative dual activation of the monomer and initiator/polymer chain‐end thanks to the HB donor ability of the squaramide moiety (for lactide activation) and the HB‐accepting character of the NMe 2 moiety (for initiator/polymer chain‐end activation). The proposed bifunctional activation mechanism, that is, activated monomer/activated chain‐end mechanism, is depicted in Scheme . Such a dual activation at a single molecular catalyst has been documented with other lactide ROP organocatalysts, most notably, amine‐functionalized thioureas and amidine‐type organics…”

Food Sweetener Saccharin in Binary Organocatalyst for Bulk Ring‐Opening Polymerization 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.…”

Organocatalysts for the Synthesis of Poly(ethylene terephthalate‐co‐isosorbide terephthalate): A Combined Experimental and DFT Study

“…Organocatalysis for polymerization reactions is a field that has gained a huge interest these last 15–20 years, notably in a sustainable chemistry background . Most of the studies were devoted to chain growth reactions, especially the ring‐opening polymerization of various types of heterocycles and the polymerization of acrylic and methacrylic monomers.…”