Synthetic Control of Helical Polyisocyanates by Living Anionic Polymerization toward Peptide Mimicry

Abstract

We include 208 references with this Perspective to describe various helical polymers, particularly polyisocyanates. Interest in polyisocyanates with helical properties is driven by various synthesis methods. Furthermore, the living characteristics of the polymerization of isocyanate have been studied with kinetics. The rigid-rod structures of polyisocyanates generate specific morphologies of block copolymers. There have also been chiral studies of polyisocyanates, which are synthesized with chiral monomers, initiators, and terminators. Hydrophilic polyisocyanates are presented through random copolymerization of allyl and alkyl isocyanates and the subsequent click reaction. Additionally, random, gradient, block, and multiblock polyisocyanates are explained by using furfuryl, allyl, and alkyl isocyanates with different reactivities. Recent works on alternating polyisocyanates are also presented. The perspective on the amphiphilic peptide-mimicking multiblock and alternating polyisocyanates is described as future work of sequence control of polyisocyanates with good water solubility and degradable properties.

Lyotropic Nematic Phases of Isotropic Nanoparticles via Semiflexible Polymer Ligands

“…[ 27 ] However, the maximum molecular weight is generally limited to < 20K due to competing depolymerization, a general problem for isocyanate polymerization reactions. [ 24 ] To address the problems listed above, a phosphonate functionalized initiator was designed, as to optimize the synthesis through reducing depolymerization and product loss through purification ( Scheme ).…”

“…Assuming a repeat unit length of 0.2 nm, [28] the contour lengths of the prepared PHIC samples are as follows in increasing order of molecular weight: 4.8, 11.0, and 36.0 nm. This places PHIC 24 and PHIC 55 below the persistence length of PHIC in DCM (l p = 20 nm) and PHIC 180 above the persistence length. The PHIC ligands were then attached to the benzyl alcohol stabilized ZrO 2 NPs through an exchange reaction followed by quantitative precipitation to remove unbound ligands.…”

“…[ 23 ] The similarity of the amide backbone of polyisocyanates to peptides has inspired investigations as more thermally stable alternatives to polypeptides. [ 24 ] The polymer persistence length, l p , is a measure of the bending stiffness that varies with the solvent. For chain lengths below l p , the polymer behaves as a rigid rod whereas for chain length well above l p , the polymer is in the continuously flexible “wormlike” state.…”

Investigation of eight-arm tapered star copolymers prepared by anionic copolymerization and coupling reaction

“…Compared with the "core-first" method depending on a multifunctional initiator, the "arm-first" route first synthesizes a linear polymer chain, which then reacts with coupling agents, leading to a high level of control over the structure of arm chains. As for the living anionic polymerization system, [38][39][40][41] the established strategies usually involve coupling reactions between living carbanionic polymer chains and electrophilic linking agents containing multifunctional chlorosilane or benzyl bromide moieties. 42,43 However, the coupling step is often time-consuming (up to several weeks) and prone to impurities.…”

Synthesis of Alternating Polyisocyanate Copolymers by Anionic Polymerization for Mimicking Amphiphilic Helical Peptides

“…[11] To achieve the amphiphilic helical conformation, an alternating sequence that can uniformly divide the interface along the polymer chain should be controlled with a helical polymer.Polyisocyanate composed of a 1-nylon backbone can adopt a helical conformation, which is well suited to mimic the structures and functions of natural peptides (Scheme 1). [12] Polyisocyanates can be polymerized either by living anionic [13] or living organotitanium(IV)-catalyzed polymerization. [14] Various polyisocyanate copolymers, such as block, [15] random, [16] and multiblock [17] have been reported, while alternating copolymerization between isocyanates has not yet been found.…”