Organocatalytic Ring‐Opening Polymerization of ϵ‐Caprolactone with Phosphoramidimidates (PADIs) as a Bifunctional Brønsted Acid Catalyst

Abstract

In this study, an organocatalytic ring‐opening polymerization (ROP) of ϵ‐caprolactone (ϵ‐CL) has been developed by employing PADIs as a novel and efficient acid/base bifunctional organocatalyst, which could afford metal‐free poly(ϵ‐caprolactone) with predictable molecular weight and narrow dispersity at a low catalyst loading under mild conditions. NMR and kinetic studies indicate that the ring‐opening polymerizations of lactones catalyzed by PADIs proceed in a living and well controlled manner. Moreover, this organic Brønsted acid catalytic system could allow the synthesis of PCL with molecular weight above 60 kg/mol, as well as well‐defined star polymers.

Amino acids as bio-organocatalysts in ring-opening copolymerization for eco-friendly synthesis of biobased oligomers from vegetable oils

“…21,22 Many vegetable oils are mixtures composed of unsaturated triglycerides, which can be chemically converted into epoxide derivatives using various synthetic routes; such vegetable oil epoxidation is an appealing process as the epoxidized vegetable oils can be employed as biobased building blocks for the preparation of polyhydroxyalkanoates [23][24][25] and non-isocyanate polyurethanes (NIPUs). [26][27][28][29][30] Several synthetic routes, such as step-growth polymerization 31 or ring-opening polymerization (ROP) of lactones, 32,33 have been reported for the preparation of polyesters using cyclic monomers (lactides and lactones) as building blocks. However, the lack of commercially available cyclic esters substantially restricts the development of innovative biodegradable polyester designs with better characteristics via ROP.…”

“…Several synthetic routes, such as step-growth polymerization 31 or ring-opening polymerization (ROP) of lactones, 32,33 have been reported for the preparation of polyesters using cyclic monomers (lactides and lactones) as building blocks. However, the lack of commercially available cyclic esters substantially restricts the development of innovative biodegradable polyester designs with better characteristics via ROP.…”

Ring‐Opening Polymerization of ϵ‐Caprolactone by Benzoic Acid in the Presence of Benzyl Alcohol as Initiator

“…Pioneered in 2001 by Hedrick and Waymouth using 4‐dimethylaminopyridine (DMAP) as the organocatalyst for the living ROP of lactide, significant advances in the organo‐catalyzed ROP have been obtained [12] . A variety of small organic molecules for ROP of ϵ‐CL have been developed, including DMAP derivatives, [13–15] N‐heterocyclic carbenes (NHCs), [16] phosphines, [17] Brønsted/Lewis bases and acids, [18–20] ionic liquids etc [21] . Among the organocatalysts, Brønsted acids represent a very effective class of catalyst for the polymerization due to the advantages such as controlled molecular weights, narrow distribution etc.…”