Aqueous Emulsion Polymerization of Substituted Acetylenes: Effects of Organic Solvent and Analysis of Blue Shifts and Emulsion Polymerization Mechanism

Abstract

A series of optically active nanoparticles composed of helical substituted polyacetylene is prepared via emulsion polymerization. A specifi c organic solvent is required for solid substituted acetylene monomers to undergo emulsion polymerization. The effects of this organic solvent are investigated. Its amount is found to be decisive for obtaining stable polymer emulsions. The helical conformations of the substituted polyacetylenes in nanoparticle state are identifi ed with the help of CD and UV-vis spectra. A blue shift occurs in CD and UV-vis spectra of some of the polyacetylene emulsions. The underlying driving force for the blue shift is discussed, and an emulsion polymerization mechanism is proposed.

Particles of polyacetylene and its derivatives: preparation and applications

“…The authors presented a schematic for illustrating the distribution of AA and DMAP molecules on the copolymeric nanoparticles surfaces (Figure 3). 59 The particles were subjected to photonic analysis, 65 demonstrating the potential as three-dimensional photonic crystals. Accordingly, the obtained copolymer particles may be applied as biosensors due to both the photonic properties and the functional groups.…”

“…phenylacetylene, the cosurfactant is not necessary. 65 The investigated monomers include two chiral N-propargylsulfamides (monomers 1 and 2, a pair of In the emulsion polymerizations of monomers 1−4, the loading 15 of surfactant (SDS) should be high enough for forming stable emulsions. Take monomer 1 as example, the SDS/monomer ratio of 1/3−1/6 (mol/mol) led to the anticipated stable polymer emulsions.…”

“…60 To optimize the particles and to make them more beneficial for practical applications, Chen et al further prepared hollow twolayered particles, following a seed-emulsion technique developed based on the emulsion polymerization approach. 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.…”

“…Namely, "chirality" inversion occurred to the polymer particles. For a vivid comparison, the CD spectra of both the polymers obtained by solution polymerization and the polymer particles obtained by emulsion polymerization are 65 displayed in Figure 7. The phenomenon of "chirality inversion" is remarkably intriguing and indicates that in forming particles, the helicity of the polymer chains underwent inversion.…”

“…(In osmosis-driven 60 self-assembly, dialysis membranes or semipermeable membranes are applied toward a polymer solution, allowing for passive transport of the non-solvent of the polymer, by which decreasing the solubility of the polymer and finally leading to slow aggregation of it into spheric particles. 95 ) Under appropriate 65 conditions, hollow nanospheres were formed from THF/water solvent system. Figure 11.…”