Study On The Synthesis And Properties Of Water-soluble Fluorene And Thiophene Polymers

Water-soluble conjugated polymers are conjugated polymers with water-soluble ionic groups in side-chain,which have excellent photoelectric properties,good stability and unique solubility.Among them,water-soluble polyfluorene and thiophene are currently studied more.Polyfluorene has a strict planar unit,high fluorescence quantum efficiency,easy to chemical modification and other characteristics;polythiophene is an important conductive polymer,with good environmental stability,after doped has a high photoelectric properties.In this paper,fluorene and thiophene were used as main chain,and homopolymers and copolymers containing different water-soluble ionic groups were synthesized by introducing water-soluble ionic groups in the side chain of fluorene and thiophene.The main contents are as follows:1?Three different polymerization methods of water-soluble polymers,enzymatic polymerization,Yamamoto polymerization and Suzuki polymerization,were studied.A series of anionic water-soluble polymers were synthesized.It was found that enzyme polymerization can realize the polymerization of single monomer,which has the advantages of simple operation,short synthesis route,green environmental protection,and easy polymerization of thiophene with relatively low oxidation potential.However,the enzyme-catalyzed polymerization is more sensitive to impurities that are reducible,and even if a small amount is present,the polymerization can not occur,which is due to the depletion of the depleted impurities by consuming the key reactant H2O2 in the enzymatic reaction.Yamamoto polymerization can achieve a relatively high oxidation of fluorene monomeric,but its purity requirements of the monomer is very strict,and the use of Ni(0)catalyst is particularly easy to deactivate the catalyst partial inactivation can lead to polymer molecular weight is very small.Suzuki polymerization is an effective method for the synthesis of copolymers.Suzuki reaction is not sensitive to water,has strong substrate adaptability and functional group compatibility,so that the polymer has a lot of space in molecular design.Suzuki method can be used through direct or indirect way to get water-soluble ionic groups of polymers,is often used in the more mature polymerization method.2?Three kinds of cationic alcohol soluble fluorene-thiophene copolymers PFT-C3-3N,PFT-C6-3N and PFT-C8-N were synthesized by indirect synthesis.That is,fluorene and thiophene as the main chain,Suzuki polymerization obtained by containing brominated alkyl side chain neutral polymer,and then quaternized ammonium salt to get the side chain containing quaternary ammonium target products.The three polymers have different side chain lengths that are well soluble in polar solvents.The effects of solvent effect and branch length on the photophysical properties of PFT-C3-3N and PFT-C6-3N were studied.With the increase of the polarity of the solvent,the UV absorption spectra and fluorescence emission spectra of PFT-C3-3N and PFT-C6-3N in different solvents occurred 3~5 nm red shift.Compared with PFT-C3-3N and PFT-C6-3N,the UV absorption and fluorescence emission spectra of PFT-C6-3N increased obviously in the solution state and film state due to the increase of the side chain length.The introduction of ionic groups reduced the thermal stability of the polymer,but the thermal stability was good before 200 °C.Since the PFT-C3-3N and PFT-C6-3N conjugate backbone are the same,the HOMO and LUMO values are close.3?Two kinds of anionic and cationic mixed alcohol-soluble fluorene-thiophene copolymers were synthesized by indirect synthesis pathway.PFT-C3-2N,Na and PFT-C6-2N,Na.Specifically,a water-soluble thiophene unit having a sulfonic acid group and a fluorene unit having a brominated alkyl side chain are synthesized by Suzuki polymerization to obtain a polymer containing an ionic group and a reactive pendant group based on fluorene and thiophene,The quaternary ammonium salt is then introduced into the ionic group in the fluorene unit to give the polymer PFT-C3-2N,Na and PFT-C6-2N,Na containing the cation-cation mixture.Both polymers have different side chain lengths that are well soluble in polar solvents.The effects of solvent effect and branch length on the photophysical properties of PFT-C3-2N,Na and PFT-C6-2N,Na were studied.With the increase of the polarity of the solvent,the UV absorption spectra and fluorescence emission spectra of PFT-C3-2N,Na and PFT-C6-2N,Na in different solvents occurred 6~10 nm red shift.The spectra of PFT-C3-2N,Na and PFT-C6-2N,Na in the solution state and the film state are almost the same,and no significant change occurs due to the interaction between the cationic and cationic interactions contained in the polymer.The effect of the electrostatic interaction between the greater,so that the impact of branch length is not obvious.The thermal stability of PFT-C3-2N,Na and PFT-C6-2N,Na is good.Since the polymers PFT-C3-2N,Na and PFT-C6-2N,Na conjugate backbone are the same,HOMO and LUMO are close.The properties of the synthesized compounds were characterized by NMR,MS,IR,UV,fluorescence,thermogravimetric,film conductivity and electrochemical properties.