Rigid, Helical Arm Stars through Living Nickel Polymerization of Carbodiimides

Synthesis of optically active star polymers consisting of helical poly(phenylacetylene) chains by the living polymerization of phenylacetylenes and their chiroptical properties

Star polymers consisting of three helical poly(phenylacetylene) chains with a precisely controlled molecular weight (molar mass dispersity < 1.03) were successfully synthesized by the living polymerization of phenylacetylene derivatives with a Rh-based multicomponent catalyst system comprising trifunctional initiators, which have three phenylboronates centered on a benzene ring, the Rh complex [Rh(nbd)Cl]2, diphenylacetylene, triphenylphosphine, and a base. The analysis of chiroptical properties of the optically active star polymers obtained by the living polymerization of optically active phenylacetylene derivatives revealed that the star polymers exhibited chiral amplification properties owing to their unique topology compared with the corresponding linear polymers.

Optically active polymer particles with programmable surface microstructures constructed using chiral helical polyacetylene

Micro/nanoparticles with surface microstructures have attracted tremendous attention due to their fascinating structures and properties. Herein, we present the first strategy for producing optically active polymer particles with varying surface microstructures via a template surface modification process in which achiral particles act as the template and helical substituted polyacetylene acts as the chiral component. To prepare the designed chiral-functionalized particles, template particles were first reacted with propargylamine to produce alkynylated template particles. The alkynylated templates further participated in the polymerization of chiral alkyne monomers through a surface grafting precipitation polymerization approach, resulting in achiral particles with surface microstructures covalently bonded with a chiral helical polymer. SEM images ascertain the production of chiral-functionalized particles showing various shapes (jar-like, golf ball-like, and raspberry-like particles). Furthermore, CD and UV-vis absorption spectra demonstrate that the grafted polyacetylene chains adopt a predominantly single-handed helical conformation, thereby affording composite particles with optical activity. Using the established protocol, numerous advanced chiral-functionalized micro/nanostructures are expected to be designed and constructed.

Supramolecular Helical Miktoarm Star Polymers

We report a hydrogen-bonded supramolecular miktoarm star polymer containing three distinct helical arms. Our design involves two helical poly(methacrylamide) arms connected by a barbituric acid (Ba) at the center, prepared through the reversible addition-fragmentation chain-transfer polymerization with a bifunctional agent. Together with a telechelic helical poly(isocyanide) end-functionalized with a Hamilton Wedge (HW) that is complementary to Ba, the two components assemble into an AB₂-type star copolymer. The assembly is driven by the hydrogen bonding between HW and Ba, which is quantified by ¹H NMR titration and isothermal titration calorimetry. Gel-permeation chromatography provides evidence for the formation of the desired miktoarm star architecture. This strategy of site-specific functionalization on helical polymers provides a modular approach to preparing nonlinear supramolecular ensembles with topologically diverse building blocks.

Nonspherical chiral helical polymer particles with programmable morphology prepared by electrospraying

Chirality and chiral materials demonstrate ever-growing importance. As a new type of chiral material, chiral polymer particles hold huge potential in both scientific research and practical applications. Meanwhile, nonspherical polymer particles (NPPs) have witnessed substantial progress in recent years because of their unique structures and especially the properties distinguishable from the corresponding spherical particles. We hypothesize that combining chirality with NPPs will open up an unprecedented category of advanced materials. The present contribution reports the first protocol for preparing electrosprayed nonspherical chiral particles constructed from chiral helical polymers, using helical substituted polyacetylenes as the model. SEM images demonstrate the successful fabrication of nonspherical chiral particles with tunable morphologies (bowl-, golf- and apple-like particles). Circular dichroism (CD) measurement proves the remarkable optical activity of the particles, which is observed in the predominantly one-handed helical polymer chains. The present work establishes a novel, versatile, and powerful platform for preparing nonspherical chiral polymer particles with controllable morphology.

The secondary structures of PEG-functionalized random copolymers derived from (R)- and (S)- families of alkyne polycarbodiimides

Macromolecular micelles: a hydrophobic polyamidine backbone surrounded by hydrophilic PEG chains.

Facile synthesis of optically active helical poly(phenyl isocyanide) brushes on a silicon surface and their chiral resolution ability

Optically active helical poly(phenyl isocyanide) brushes grafted on a silicon surface were prepared and their chiral resolution ability was investigated.

Gradient helical copolymers: synthesis, chiroptical properties, thermotropic liquid crystallinity, and self-assembly in selective organic solvents

A series of novel gradient copolymers R-(−)-poly(StN-grad-C8) were synthesized through atom transfer radical copolymerization of an achiral styrenic monomer, N,N-dimethyl-4-ethenylbenzamide (M-StN), and a chiral bulky vinylterphenyl monomer, (−)-2,5-bis{4′-[(R)-sec-octyloxycarbonyl]phenyl}styrene (R-(−)-M-C8).