The Synthesis Of New Structural Polymer Materials By "Double Click Polymerization"

With the rapid growth of the economy,the demand for materials is also increasing.The development of high performance materials with new structure,especially for the development of light-emitting materials and heat-resistant materials is the goal of many researchers.Since the light-emitting materials and heat-resistant materials have great application prospects in the market,therefore the development of a simple,convenient post-processing method of synthesis has great necessity.Click chemistry is a chemical transformation with such advantageous characteristics as good tolerance of functional groups and solvents,moderate reaction temperature,simple product processing steps and so on.It has become an important synthetic method for the preparation of new structural materials.Based on the research outcome of our laboratory,this paper reported a new synthestic method-double click polymerization for the preparation of new structural polyfluorenes light emtting materials and heat-resistant materials.For the preparation of polyfluorenes,2,7-dicarboxaldehyde-9,9-dialkylfluorene had been used as double-terminal aldehyde monomer and 1,4-diethynylbenzene had been used as double-terminal alkyne monomer.Condensation 2,7-dicarbo xaldehyde-9,9-dialkylfluorene with p-toluenesulphonyl hydrazide for the first clikc reaction as "non-aldol" type reaction followed by treatment with an aqueous solution of sodium hydroxide leaded to the diazocom pounds.Finally,the 1,3-dipolar cycloaddition of diazo compounds onto acetylene would lead to three 3,5-disubstitued pyrazole-linked polyfluorenes.The three polymers had reasonable molecular weight and narrow molecular weight distribution,exhibited blue emission(maximum of emission around 450 nm) and good solubility in N,N-dimethylforma mide at room temperature.They also possessed good thermal stability and processability.We also prepared new structural heat-resistant materials by"double click polymerization".Terephthalaldehyde,4-(4-formylphenoxy)benzalde hyde and 4,4'-biphenyldicarboxaldehydes had been used as three kinds of double-terminal aldehyde monomers.After two click reactions,3,5-disubs tituted pyrazole-linked polymers in main chain were obtained,and they all had a higher molecular weight and narrow molecular weight distribution. The two polymers of them showed good sulublity in N,N-dimethylforma mide (DMF) and dimethylsulfoxide (DMSO),but the another one polymer using 4,4'-biphenyldicarboxaldehydes as double-terminal aldehyde monomers was difficult to dissolve in common organic solvent.These three polymers showed thermal stability and the Tg of the three polymers were greater than 120?.In the air,5% weight loss temperature was higher than 300?,in nitrogen 5% weight loss temperature was higher than 330?,and the char yield was greater than 45%.