Study On The Synthesis And Properties Of Helical Polyacetylenes Bearing Fluorene Side Groups

Helical polymers not only show unique electronic, magnetic and optical properties but also possess significant potential applications in many field due to the molecular recognition ability, catalytic ability for asymmetric synthesis, and optical resolution ability. Substitute polyacetylenes as a kind of important helical polymer have attract many interests in recent years due to their special properties, such as semiconductor, nonlinear optical, etc.Fluorene is a new type of promising luminescence materials in the area of organic light-emitting. Fluorene and its derivatives have high thermal stability and chemical stability due to the rigid planar biphenyl unit in their molecular structure, and they can emit different wavelengths of light by copolymerization, blending or other methods. Therefore, they have potential applications in the field of flat panel displays, chemical sensors, nonlinear optics and solar cells, et al. It is foreseeable that polyacetylene which contain fluorene illuminophore in the side chain will integrate these features and develop a new kind of functional materials.We synthesized a new type of mono-substituted polyacetylene monomers which polymerized under the chloronorbornadiene rhodium (Ⅱ) dimmer [(nbd)RhCl]2 catalyst, and obtained a new type of mono-substituted helical polyacetylene homopolymers, poly 4-(2-fluorene-based)-3-oxo acid amide [P1], poly 4-(2-fluorene-based)-3-oxo acid propargyl ester [P2], poly N-propinyl-L-alanine-4-(2-fluorene-based)-3-oxo butylamide [P3] and poly 4-(2-fluorene-based)-3-oxo acid-L-alanine-propargyl ester [P4], and also obtained polyacetylene copolymers with different molar ratio of monomers M2 and M3, poly {4-(2-fluorene-based)-3-oxo acid propargyl ester)-(N-propinyl-L-alanine based-4-(2-fluorene-based)-3-oxo butylamide, M2:M3=3:7, molar ratio} [P5] and poly{4-(2-fluorene-based)-3-oxo acid propargyl ester)-(N-propinyl-L-alanine based-4-(2-fluorene-based)-3-oxo butylamide, M2:M3=7:3, molar ratio} [P6], and their properties were also investigated. The structures and properties of these polyacetylenes were investigated by 1HNMR, FT-IR, UV-vis, CD, TGA, DSC, FL and other methods. The results showed that those polymers have good luminescent properties and thermal stability, and also have stable helical structure, is a new type of optical activity polyacetylene, and will have its potential applications in many areas.The substituted polyacetylenes synthesized in this thesis were characterized by UV-vis and fluorescence spectroscopy, in spite of the differences in their molecular structures, the dilute solutions (1×10-5mol/L) of these substituted polyacetylenes exhibit the same absorptions and the same blue emissions; then we investigated the effects of concentration on FL spectra of polymers, and found that the light-emitting wavelength undergo red shift, emitting color and fluorescence intensity changed as the concentration increased.CD test indicated that polyacetylenes synthesized in this thesis have helical structure, solvents-mixed and temperature-changed CD test indicated that polyacetylenes synthesized in this thesis have stable helical structure, because they still have helical structure even under the conditions of polar solvents (CH3OH) content of 90% and higher temperature (60℃), which are quite different from the helical conformation of polyacetylenes disappeared with the increase of solvent polarity and temperature that reported in previous articles.In the end we summarize the work simply, and make an outlook about the application of the mono-substituted helical polyacetylenes we prepared and the research work we will do in the future.