Utilization of a Kinetic Principle of the Sequence-Controlled Anionic Copolymerization of Isocyanates toward Polyisocyanate Copolymers Encoded with Multiple Monomer Sequences

Abstract

Furfuryl isocyanate (FIC), allyl isocyanate (AIC), and n-hexyl isocyanate (HIC) that have different β-carbon substituents were employed as monomers in living anionic homo- and copolymerization. The rate constants of the self- and cross-propagation reactions were determined, and their comparison showed the electrophilicity order of isocyanate as FIC > AIC > HIC. The kinetic analysis revealed that the anionic copolymerization of FIC:HIC, AIC:HIC, and FIC:AIC generated three different sequence-controlled polyisocyanate copolymers, poly­(furfuryl isocyanate-block-n-hexyl isocyanate) (P­(FIC-b-HIC)), poly­(allyl isocyanate-tapered block-n-hexyl isocyanate) (P­(AIC-tb-HIC)), and poly­(furfuryl isocyanate-gradient-allyl isocyanate) (P­(FIC-grad-HIC)), respectively. The homogeneous sequential anionic copolymerization of the binary isocyanate mixtures generated the polyisocyanate copolymers having repeated monomer sequences. A series connection of P­(FIC-b-HIC), P­(AIC-tb-HIC), and P­(FIC-grad-HIC) segments in the copolymer was attempted by heterogeneous sequential anionic copolymerization of the binary isocyanate mixtures. The variation of the comonomer addition order allowed the resulting polyisocyanate copolymers to be encoded by the three combined monomer sequences.

Alternating Copolymerization Realized with Alternating Transformation of Anion-Migrated Ring-Opening Polymerization and Anionic Polymerization Mechanisms

“…Generally, terpolymers exhibit better properties than homo- or copolymers because multiple functional groups are integrated. However, how to precisely control the sequence distribution has been a bottleneck for terpolymerization . In this work, the features of the alternating copolymerization of CPVB with DPE derivatives were well investigated.…”

“…However, how to precisely control the sequence distribution has been a bottleneck for terpolymerization. 44 In this work, the features of the alternating copolymerization of CPVB with DPE derivatives were well investigated. An alternating sequence structure was achieved because of the alternating transformation of the AMROP and AP mechanisms during copolymerization, but the reactivity of the DPE derivatives exhibited no effects.…”

Simple and Precision Approach to Polythioimidocarbonates and Hybrid Block Copolymer Derivatives

“…Sequence-controlled copolymerization represents an attractive area of research for the fabrication of soft materials with diverse, tailored, and advanced structures, compositions, and properties. − In this context, epoxides have been widely explored as a class of versatile building materials in copolymerizations. − A large variety of (bio)­degradable and/or functional polyethers, , polyesters, and poly­(thio)­carbonates have been produced by direct (alternating) copolymerization of epoxides and heterologous compounds such as lactones, , cyclic anhydrides, − coumarin derivatives, − and carbon dioxide − and its sulfur analogues. − Isocyanates, the most commonly found substituted heteroallenes, are also shown to undergo copolymerization with epoxides in a few recent reports. So far, the monomer scope has been limited to electron-deficient p -tosyl isocyanate and aryl isocyanates, − and copolymerization of the latter remains uncontrolled with small-molecule byproducts (oxazolidinones) and heterogeneous backbone composition formed (with isocyanurate linkages). − …”

Living Initiator-Transfer Anionic Polymerization of Isocyanates by Sodium Diphenylamide

“…Besides, the method had a limitation in the compositional control of polymer due to the typical reaction kinetics that is barely dependent on the monomer structure . Afterward, our group has developed several advanced techniques for living anionic polymerization of isocyanates. − These successfully allowed access to model polyisocyanates with quantitative yields, predictable MWs, and low dispersities and complex polymers with tailored macromolecular architectures in composition, ,,− chirality, − functionality, − and topology. ,, Such profound control over the structure of the polyisocyanates led us to the conclusion that the living anionic polymerization of isocyanates is the most promising method to create synthetic macromolecules possessing unique three-dimensional structures and functions, as shown in proteins.…”