Micelle-provided microenvironment facilitating the formation of single-handed helical polymer-based nanoparticles

Abstract

Microenvironments have been found to play critical roles that cannot be realized in bulk reaction systems. Optically active particles, particularly those constructed by chiral helical polymers, have attracted much interest. However, most of the optically active polymer particles were derived from chiral monomers. In the present study, achiral substituted acetylene monomer underwent polymerizations in micelles (emulsion polymerizations) and in solution (solution polymerizations) in the presence of rhodium catalyst and chiral additive. The emulsion polymerizations provided optically active polymer nanoparticles consisting of helical polymers forming predominantly one-handed screw sense, while the corresponding solution polymerizations provided helical polymers containing both right-and left-handed helices in identical content (racemic helical polymers). The exciting finding of helix-sense-preferring effect in emulsion polymerizations is due to the specific spatial microenvironment offered by the micelles. To further improve the thermal stability of the induced macromolecular helicity, core/shell structured particles were prepared by successive emulsion polymerization route, in which the shells provided protection for the cores. Scheme 1. A schematic showing polymerization of achiral monomer (M) in the presence of chiral additive (CA): (A) emulsion polymerization (HSSEP); (B) solution polymerization; Route (A) also includes the preparation of optically active core/shell nanoparticles.

Optically Active Helical Polyacetylene Self-Assembled into Chiral Micelles Used As Nanoreactor for Helix-Sense-Selective Polymerization

“…As a control, we also performed HSSP of achiral monomer M by using achiral emulsifier Triton X-100 and (R)-(+)-phenethylamine according to our previous work. 43 The detailed processes are presented in the SI. Figure S12 illustrates the TEM image of the prepared polyM nanoparticles.…”

Chiroptical Elastomer Film Constructed by Chiral Helical Substituted Polyacetylene and Polydimethylsiloxane: Multiple Stimuli Responsivity and Chiral Amplification

“…In view of the temperature sensitivity of helical substituted polyacetylenes, , we next studied the optical activity of the chiral copolymer S -P­(SA 7 -VA 3 ) in the solution state, which was taken as a control sample. From Figure S7, the CD signals gradually became weaker with increasing temperature.…”

Preparation and Applications of Chiral Polymeric Particles

“…Following the same concept, R/S-phenylethylamine (R/S-PEA) were separately used to perform HSSEP. [49] When achiral monomers underwent emulsion polymerization with R-PEA or S-PEA as chiral additives, HSSEP was carried out smoothly and provided CPPs. Unfortunately, when the polymerization was carried out in solution, the resulting polymers failed to show optical activity.…”