Polymerization of Polar Monomers Mediated by Main-Group Lewis Acid–Base Pairs

Abstract

The development of new or more sustainable, active, efficient, controlled, and selective polymerization reactions or processes continues to be crucial for the synthesis of important polymers or materials with specific structures or functions. In this context, the newly emerged polymerization technique enabled by main-group Lewis pairs (LPs), termed as Lewis pair polymerization (LPP), exploits the synergy and cooperativity between the Lewis acid (LA) and Lewis base (LB) sites of LPs, which can be employed as frustrated Lewis pairs (FLPs), interacting LPs (ILPs), or classical Lewis adducts (CLAs), to effect cooperative monomer activation as well as chain initiation, propagation, termination, and transfer events. Through balancing the Lewis acidity, Lewis basicity, and steric effects of LPs, LPP has shown several unique advantages or intriguing opportunities compared to other polymerization techniques and demonstrated its broad polar monomer scope, high activity, control or livingness, and complete chemo-or regioselectivity, as well as its unique application in materials chemistry. These advances made in LPP are comprehensively reviewed, with the scope of monomers focusing on heteroatom-containing polar monomers, while the polymerizations mediated by main-group LAs and LBs separately that are most relevant to the LPP are also highlighted or updated. Examples of applying the principles of the LPP and LP chemistry as a new platform for advancing materials chemistry are highlighted, and currently unmet challenges in the field of the LPP, and thus the suggested corresponding future research directions, are also presented. CONTENTS 4.1.4. Vinyl Phosphonates 4.1.

Phosphazene/Lewis Acids as Highly Efficient Cooperative Catalyst for Synthesis of High‐Molecular‐Weight Polyesters by Ring‐Opening Alternating Copolymerization of Epoxide and Anhydride

“…Among these, Lewis pairs could be the most attractive one. Although the ROAC of anhydride and epoxide by Lewis pairs remains in its infancy, it is becoming a powerful polymerization technique and has shown unique advantages, benefitting from the cooperative monomer activation and chain initiation, propagation, termination, transfer processes . Moreover, carefully tuning the acidity–basicity and steric effects could result in a large number of Lewis pairs with distinctive catalytic properties.…”

An Investigation on the Production of Random Copolymer with Monothiocarbonate and Trithiocarbonate Units over Cyclic Thiocarbonate via Metal‐free Catalysis

“…Catalyst design is usually the core of meditating a polymerization process . Confined by the difficulty in intricate design and multiple synthesis steps of metal catalyst, modifying of the polymer by varying catalyst structure faces great troubles.…”

Lewis‐Pair‐Mediated Selective Dimerization and Polymerization of Lignocellulose‐Based β‐Angelica Lactone into Biofuel and Acrylic Bioplastic

“…At the outset, we investigated the polymerization of b-AL by different methodologies,i ncluding group transfer, [12] coordination-addition, [13] and radical polymerizations,b ut none of them were active (see Table S1 in the Supporting Information). As anewly emerged polymerization technique, Lewis pair polymerization (LPP), [14] catalyzed by frustrated Lewis pairs (FLPs) [15] or classical Lewis adducts (CLAs), has been shown to be an effective strategy for polymerizing polar vinyl monomers, [16] and for ring-opening polymerization of cyclic esters and epoxides, [17] thanks to synergistic/cooperative monomer activation and the ability to stabilize propagating active species.W eh ypothesized that successful polymerization of b-AL could be achieved if aL Pc atalytic system could be rationally designed by enhancing the activation of monomer and suppressing the chain-transfer events.G uided by this hypothesis,w ef irst chose 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (I i Pr, Scheme 1D), at ypical N-heterocyclic carbene which is both ag ood nucleophile and excellent base,a st he Lewis base (LB) to construct LPs in combination with different Lewis acids (LAs). Ac ontrol reaction run at room temperature (RT) using I i Pr alone yielded only dimer with al ow b-AL conversion of 41.0 %i n 24 hours (see Table S2, run 1).…”