Ring-Opening Polymerization of Epoxides: Facile Pathway to Functional Polyethers via a Versatile Organoaluminum Initiator

Abstract

We report a new class of organoaluminum-based initiator for anionic ring-opening polymerization of epoxides that is simple to synthesize from readily available precursors. The resultant organometallic initiator was the triethyl­aluminum adduct of (2-dibenzyl­amino)­ethoxy­diethylaluminum (TAxEDA) [(AlEt3)·(O­(AlEt2)­CH2­CH2N­(Bn)2)], which was isolated by direct crystallization from the reaction medium and then compositionally and structurally characterized by NMR spectroscopy and XRD. We studied the reactivity and versatility of the new initiator through the polymerization of propylene oxide, butylene oxide, epichlorohydrin, and allyl glycidyl ether into homopolymer, statistical copolymer, and block copolymer architectures with heterobifunctional end-groups consisting of dibenzylamine and hydroxyl functionalities. The TAxEDA-initiated polymerizations were consistent with a controlled, living, anionic mechanism that was tolerant of chemical functionality and exhibited no chain transfer to monomer that limits the traditional anionic ring-opening polymerization of substituted epoxides.

Tunable temperature‐ and shear‐responsive hydrogels based on poly(alkyl glycidyl ether)s

“…Living anionic polymerization is an effective method for the ring‐opening polymerization of glycidyl ether derivatives to afford polymers of controlled molecular weight and dispersity. All poly(alkyl glycidyl ether)s in this investigation were synthesized via the initiation from an alcohol using potassium naphthalenide as the base.…”

“…The reaction continued for 24 h at 65 °C and was subsequently quenched with a degassed solution of 1% (v/v) AcOH in MeOH. In the polymerizations with AGE, reactions were performed at 30 °C to avoid allyl–vinyl isomerization as reported by Lynd and co‐workers . The reaction mixture was then precipitated into cold hexane.…”

Recent Developments on the Use of Group 13 Metal Complexes in Catalysis

“…Owing to their Lewis acidity, Al III ‐based species have long been used as catalysts in the ROP of epoxides for the production of valuable polyethers with various properties. Inspired by the Vanderberg's catalyst, an ill‐defined aluminoxane‐based catalyst industrially implemented for the production of elastomeric polyethers, a novel family of discrete dinuclear mono‐ μ ‐oxo aluminum complexes ( 29 , Scheme ) was recently developed for the highly regioselective ROP of a broad array of functionalized epoxides . Though proceeding with a moderate activity, the polymerization catalysis is well‐controlled and leads to narrowly disperse polyethers with controllable and precise chain lengths (best run in neat PO: PO/ 29 =433, 90 % conv.…”

Ring‐Opening Copolymerization of Maleic Anhydride with Functional Epoxides: Poly(propylene fumarate) Analogues Capable of Post‐Polymerization Modification

“…[25] In this study,b oth Megastokes 673azide dye and aG RGDS peptide were attached to the propargyl functionalized chain end after scaffold crosslinking to demonstrate the feasibility of using the reactive handles and click-type reactions for post-printing bioconjugate addition. [39,40] By using af unctional monomer approach, the stoichiometry of the respective epoxide can be controlled and multifunctional polymer chains are possible. Thefunctionalization of MA significantly alters the reactivity of the alkene group, [38] which will decrease or sacrifice the ability of PPF to undergo photo-crosslinking reactions.…”

“…Alternatively,epoxides can be modified easily to incorporate ap endent functional group into the chain. [39,40] By using af unctional monomer approach, the stoichiometry of the respective epoxide can be controlled and multifunctional polymer chains are possible. [41][42][43] Herein, we utilize ROCOP of MA and functional epoxides to produce aseries of chloro-, propargyl-, and o-nitrophenyl-functionalized PPF analogues that can undergo post-polymerization and post-print type reactions for the rapid attachment of bioactive conjugates.…”