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.