Preparation And Properties Of Nanoparticles Constructed From Helical Substituted Polyacetylenes

Substituted polyacetylenes are one kind of unique polymers. Their main chains usually adopt helical architectures which always exhibit intriguing optical activity. Therefore, substituted polyacetylenes have been widely applied in significant areas such as asymmetric catalysis,enantioselective crystallization and chirally controlled release. On the other hand, polymer nanoparticles have attracted ever-increasing attention and found various applications in the last decades. They demonstrate some special characteristics like surface effect and small size effect which particles with other sizes do not possess. However, a majority of the polymeric nanoparticles created so far are derived from vinyl polymers.Researches on nanoparticles constructed by acetylenic polymers are hardly found in literature. Therefore, design and synthesis of novel acetylenic nanoparticles are of great significance in the field of chiral chemistry and material science, etc. In this dissertation, we prepared two types of acetylenic nanoparticles and the major research contents are shown as follows:1. Polymeric nanoparticles are constructed by aromatic acetylene derivatives(phenylacetylene and 1-naphthylacetylene) through suspension polymerization apporch. FTIR, NMR, SEM, UV-vis measurements are conducted to manifest the structure and morphology of nanoparticles.Two factors (stirring speed and stabilizer) influencing the formation of nanoparticles are systemically investigated. The results show that the stirring speed of 500 rpm and using polyvinyl pyrrolidone as stabilizer are the optimized conditions to prepare satisfactory nanoparticles.2. Hollow nanoparticles are constructed by substituted polyacetylene(chiral substituted acetylenic monomer or phenylacetylene) through the seed emulsion polymerization approach. Firstly, SiO2/substituted polyacetylene core/shell nanoparticles are prepared by using silica nanoparticles (mean diameter: 150 nm) as cores. Then, by removing the silica cores with hydrofluoric acid, we obtain the anticipated hollow nanoparticles. The morphology of nanoparticles is confirmed by TEM.CD and UV-vis absorption spectra demonstrate the substituted polyacetylene chains constituting the nanoparticles possess stable helical conformation with predominantly one-handed screw sense and accordingly the hollow nanoparticles possess considerable optical activity.