Optically active composite nanoparticles with chemical bonds between core and shell

Abstract

A facile methodology was developed to prepare a novel type of core/shell nanoparticles (NPs) with optical activity and with chemical bonds between the cores and shells. The cores were prepared via catalytic emulsion copolymerization of substituted acetylene comonomers in which one monomer contains azo groups in side chains. For preparing the core/shell NPs, the azo groups in the seed particles (i.e., cores) subsequently act as initiators for vinyl monomer to undergo free radical polymerizations, yielding the shells. This situation resulted in chemical bonds between cores and shells. Both the seed emulsion and core/shell nanoparticle emulsion exhibited optical activity, derived from the polyacetylenes adopting helical conformation of predominant handedness. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Particles of polyacetylene and its derivatives: preparation and applications

“…However, the exact process for it is yet unknown clearly at present. This finding may motivate more investigations on chiral polymers, 70 hopefully in turn deepening our understanding about "chirality" and chiral macromolecules, widely occurring features in Nature. Apart from the well-established emulsion polymerizations in aqueous media, emulsion polymerizations can also be carried out in organic solvents, forming the so-called oil-in-oil polymer 80 emulsions.…”

“…46 The purpose 65 for preparing such hollow particles is to increase the specific surface area, allowing them to be potentially applicable in drug release, as nanoreactors for asymmetric catalysis, etc. Following the methodology created in the aforementioned studies, Deng group further prepared more versatile nanoparticles by starting 70 from chiral and achiral substituted acetylenes. The nanoparticles include core/shell particles in which the cores and shells are linked by chemical bonds 70 and core/shell nanoparticles in which the shells consisted of vinyl copolymers.…”

“…Certainly, these practices will in turn provide new insights into the homochiral feature of Nature. 70 Studies of acetylenic polymers are motivated primarily by the typical conjugated chain structures and the envisioned applications. Most recently, the findings of the polyacetylenes being able to form chirally helical structures further stimulate more interest in them.…”

“…Also remarkably, synergic effects between the helical polymer backbones and the pendant proline moieties occurred in the asymmetric catalysis. This mimics the bioenzymes to some degree, which are well recognized for their 70 asymmetric catalysis ability. The study of Zhang et al offers new possibilities for designing and preparing polymer-based organocatalysts, which show desirable advantages especially in easy recycling, when compared to the small-molecule organocatalysts.…”

“…[40][41][42] The preparation of polyacetylene particles (both in emulsions and dispersions) demonstrates the following importance: (1) In academic research: For vinyl monomers, they currently can undergo emulsion, dispersion and suspension polymerizations in aqueous media with much ease. So similar studies dealing with 70 acetylenes shall be of significance in academic research, and will enrich the basic knowledge on polymers. (2) In applications: The practices dealing with aqueous and nonaqueous acetylenic polymer particles shall provide advanced materials and feasible processing routes for polyacetylenes.…”