Optically active hollow nanoparticles constructed by chirally helical substituted polyacetylene

Abstract

Numerous vinyl polymer-based hollow particles have been intensively explored, however it still remains a big academic challenge to prepare their counterparts derived from acetylenics. Excitingly, we achieved the first hollow nanoparticles constructed by helical substituted polyacetylene through the seed emulsion polymerization approach. Alkynylated SiO₂ nanoparticles served as seed emulsion, in which a substituted acetylene monomer (chiral M1 or achiral M2) and a cross-linker underwent emulsion copolymerization by using (nbd)Rh⁺B⁻(C₆H₅)₄ as a catalyst. The emulsion polymerizations led to core/shell structured nanoparticles. After etching the SiO₂ cores, the core/shell nanoparticles were transformed into hollow architectures. Both the core/shell and hollow particles were confirmed by TEM. CD and UV-vis absorption spectra demonstrated the helical conformations of the substituted polyacetylenes forming the core/shell and hollow nanoparticles. Thermogravimetric analysis showed the high stability of the hollow nanoparticles. The present study establishes a novel class of hollow particles, in particular the ones showing optical activity. The preparation strategy provides a versatile platform for developing analogous hollow particles derived from acetylenics.