| Recently, helical substituted polyacetylene with unique secondary structure and conjugated backbone have attracted ever-increasing attention of polymer scientists. Polyacetylene itself exhibits special properties, such as electroconductivity and Paramagnetism owing to its conjugated structure with Alternating single and double bonds. However polyacetylene material is hard to dissolve, manufacture and its stability is relatively low which limit its application. To overcome these drawbacks, researchers replaced the hydrogen atom on the polyacetylene backbone with some suitble side groups. Furthermore, they found some of the resulting polymer formed helical structure.(helical substituted polyacetylene) Helical substituted polyacetylene with functionalized side groups has showed a lot of interesting properties, such as optical activity, enantioselective separation, enantioselective recognition, asymmetric catalysis, macromolecular helicity memory etc.Fluorescence as a natural phenomenon has been studied for a long period of time. If we combine helical substituted polyacetylene with fluorescent technology in one entity, novel, fascinating, and significant materials shall in theory be developed. In this thesis, we prepared two kinds of substituted acetylene monomer. One of them is fluorescent, the other is both chiral and fluorescent. They both underwent precipitation polymerization process, providing spherical microparticles. Afterward, these two kinds of microparticles were subjected to different application experiments. The study of fluorescent microparticles revealed the mechanism of precipitation polymerization. Meanwhile, the chiral, fluorescent microparticles showed interesting ability in enantioselective recognition.The major contents are as follows:1. This thesis reports the first fluorescent microparticles (MPs, approximately 600 nm in diameter) constructed using helical substituted polyacetylene and prepared via a precipitation polymerization approach. The MPs judiciously combine this interesting helical conjugated polyacetylene, fluorescent material and polymeric particles in one entity. The monomer containing a dansyl group undergoes precipitation polymerization in butanone/n-heptane mixed solvent, with (nbd)Rl+B-(C6H5)4 as a catalyst. MPs with a regular morphology are formed in a high yield (>80\wt%). UV-vis spectroscopy demonstrates that the polymer chains making up the MPs adopt helical structures. The MPs show considerable fluorescence emission (λmax,500nm; excited at 340 nm). Based on SEM and fluorescence images, the formation mechanism of the MPs is proposed. This methodology opens up new ways to prepare functional microstructured materials derived from substituted polyacetylenes, and may also result in opportunities for new practical applications of polyacetylene and its derivatives.2. Microparticles simultaneously showing optical activity and fluorescence were prepared based on fluorescent, optically active helical polymers. Chiral and fluorescent substituted acetylene monomers (L-and D-CFM) were synthesized and then underwent precipitation polymerization in a solvent mixture of CHCl3/n-heptane in the presence of Rh catalyst at room temperature. CHCl3/n-heptane mixture at a suitable ratio provided spherical microparticles (L- and D-CFMPs) with uniform diameter of 910 nm in high yield (ca.90 wt%). The microparticles were comprised of polymer chains (number-average molecular weight,8700 g/mol) that were found to adopt chiral helical structures, accordingly to circular dichroism and UV-vis absorption spectroscopy. The fluorescence property was measured using fluorescent microscopy and spectroscopy. Remarkably, the novel microparticles exhibited enantioselective recognition ability towards alanine and phenylethylamine enantiomers. However, L- and D-CFMPs behaved differently in the enantioselective recognition processes. Possible mechanisms were proposed for the observed enantioselective recognition. |
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