Study On The Synthesis, Performance And Application Of Hyperbranched Conjugated Polymers Without Transition Metal Catalysis

The unique properties of hyperbranched conjugated polymers,such as the good solubility,adjustable electrical properties and product processability,have stimulated the research interests in view of their widespread applications ranging from organic electroluminescence,ion detection,biological identification.The pioneer metal-catalyzed polymerization methods,including the Suzuki coupling polymerization,click polymerization,and Sonogashira coupling polymerization have been proposed for the synthesis of hyperbranched conjugated polymers.These methods,however,requires harsh conditions and harmful transition-metal catalysts and solvents.Although some transition-metal-free catalysed methods have been attempted to develop the linear conjugated polymers,their usage are still rarely explored in the preparation of hyperbranched conjugated polymers.Thus the ideal synthetic approaches of hyperbranched conjugated polymers,involving only the facile procedures with eco-benign synthetic conditions,should be further explored.This thesis project aims to 1)design the hyperbranched conjugated polymers,which contain carboxylic ester groups appended to repeating 1,3-butadiene units and 2)to investigate the performance and application of the polymers.(1)In this work,we synthesized a series hyperbranched conjugated polymers based on our reported polymerization method.The polycondensation was carried out under refluxing in ethanol for 72 h with 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)as the catalyst.P1 and P2 were synthesized by the simple AB2 protocol and P4,P5,P6,P7 and P8 were synthesized by the A3 type monomer[1,1':3',1"-terphenyl]-4,4",5'-tricarbaldehyde copolymerization with five kinds of B2 type monomer,respectively.(2)The structures of polymers were determined by 1H NMR and FT-IR.The results indicated successful synthesis of the target polymers containing 1,3-butadiene units.Molecular weight test and thermogravimetric analysis confirmed the relatively good molecular weight and thermal stability of the polymers.The test of photophysical properties indicated the polymers have impressive fluorescence cmission and UV absorption spectra in THF,which demonstrates the potential of further exploration.(3)Based on the signal amplification properties of coniugated polumers for fluorescence sensing,we investigate the ion sensing property of the as-developed polymers.The results indicate the good selectivity of polymers toward the sensing of Fe3+and are non-affection by other ions in THF.At low concentration,the photoluminescent spectra of the hyperbranched conjugated polymers decreases with the concentration of quencher linearly.The results show the potential use of several hyperbranched conjugated polymers as fluorescence sensors.(4)To further expand the sensing application of metal ions in the aqueous solution,we hydrolysised neutral carboxylic-estercontaining polymer P1 and successful synthesis of the target water-soluble hyperbranched conjugated polymer P3 with the side chain contains carboxylic acid groups.The results show that P3 can be used as fluorescence sensors to achieve high selective and sensitive detection of Fe3+ in aqueous solution,thus exhibit the optential use in environmental or biological system.