Synthesis And Properties Studies On Polyimides Containing Cyclohexanylmethyl And Fluorinated Structures

The traditional aromatic polyimides have excellent thermal stability,mechanical properties,chemical resistance and so on,therefore it was widely applied in aerospace,automotive electronics,petrochemical and other fields.With the rapid development of science and technology,polyimide material through technological breakthroughs and material innovation to promote microelectronic products tend to multi-function,high-performance,portability and flexibility in the field of modern information technology.In order to solve the problems of signal delay loss and power loss and heat generation in integrated circuits under high-density and high-precision environments and to meet the application requirements of flexible wearable devices,therefore,it is imminent to develop a new generation of high-performance low-dielectric,high-transparency and colorless functional material.Polyimides are regard as an important appilication materials,so it's a significance issue to how to exploit a new low-dielectric and high transparent polyimide materials,inhibiting the formation of CTC effect is a essential way.Therefore,we designed introducing a cyclohexylmethyl,and trifluoromethyl structure pulling into the polyimide backbone in order to improve its performance.My research mainly starts from the following two step:First,a readily available 4-trifluoromethylacetophenone as the starting materials,reacted with phenol,under the catalysis of 80%concentrated sulfuric acid to give a diphenol structure,then a classical substitution reaction under the catalysis of K₂CO₃gives a dinitro compound,after going reaction get versatile diamine monomer.Using new kind of fluorinated diamine were polymerized with four aromatic dianhydride ODPA,BPDA,BTDA and PMDA to form different degrees of fluorinated two series polyimides were named MPI₁-MPI₄ and PPI₁-PPI₄,respectively.At the same time,a comprehensive properties test of the two series were performed.In the solubility,the MPI series were significantly better than the PPI series.As for the optical performance and thermal performance,MPI series and PPI series in T₅₀₀ the transmittance is in the range of 69.3-85.4%and 61.1-80.5%,respectively.The glass transition temperature was in the range of 262-288°C and 284-369°C.Therefore,it indicated that the MPI series show a better optical performance and thermal performance.Secondly,diamine monomer was got by three-step reaction,which based on Cyclohexylcarbaldehyde as the beginning material.The novel diamine monomer were polymerized with four commercially dianhydride,ODPA,BTDA,BPDA,PMDA,to give the new PI,were named FCPI_a-d-d and CPI_a-d,respectively.The two series PIs were measured a totally properties test.By measured,it found that the solubility and opticl performance of FCPI were obviously better than the CPI series.In thermal and mechanical properties,the glass transition temperature of FCPI series and CPI series were 229-277?,and 230-300?,respectively.The thermal weight loss 5%of FCPI series and PI series were 470-482?and 471-483?in the nitrogen environment.The tensile strength of FPI series and CPI series were 90.2-101.8 MPa and 78.7-99.6MPa.It indicated that the introduction of Cyclohexylmethyl and trifluoromethyl structure polyimide better maintain good thermal and mechanical properties.