Synthesis Of Novel Hyperbranched Fluorinated Polyimides And The Preparation Of Copolymerization Polyimide/au Nps Nanocomposite Films

As a kind of advanced materials with many high comprehensive performances,polyimide has been widely applied in daily life and high technology,such as heat-resisting materials for aviation,flexible printed circuit board in micro-electronics,photoresist films,adhesives and separation membranes.However,polyimide is an insoluble and don't melt materials,which limits its widespread applications.Hyperbranched polyimides can be dissolved in common organic solvents easily,this is because its abundant branched structures has prevent the molecular chain entanglement and made it difficult to crystallize.Recently,nitro-phenol derivatives which exist in industrial and agriculture waste water have attracted great attentions,and in our country,nitro-phenol derivatives are one of the priorities water pollutions which must be controlled.In the process of catalytic reduction of nitro-phenol compounds,gold nanoparticles?AuNPs?showed high efficiency,environmental friendly and quickness,and is unanimously recognized the scientific workers.However,AuNPs as catalytic material,it was easy to reunite,not stable,difficult to recycle and reuse,and high cost,all these drawbacks make it very hard to produce in large-scale and common use.So by the method of immobilizing AuNPs on polymer,metal or inorganic templates,to prepare different gold nanocomposite materials,not only solved the AuNPs reunion in the catalytic process,and can reuse,recycle and reduce the costs.Linear copolymerization polyimide?co-PI?as matrix material,not only has wonderful solubility property,and the nanocomposite films can prevent AuNPs reunion.So,from the prospective of how to improve the PI processing performance,we have prepared a new kind of triamine monomer,which with a structure that have a long arm,flexibleetherandtrifluoromethylgroups.Firstly,theintermediate4-?2-trifluoromethyl-5-nitrophenoxy?-acetophenone?p,p-FNPAP?was obtained by the nucleophilicsubstitutionreacytionbetween4-hydroxyacetophenoneand2-Chloro-5-nitrobenzotrifluoride;secondly,under the effects of catalytic,three molecules of p,p-FNPAPcondensateintotheintermediateproductof1,3,5-tris?4-?2-trifluoromethyl-4-nitrophenoxy?phenyl?benze-ne?TTFNPOPB?by the reaction of benzene;finally,1,3,5-tris?4-?2-trifluoromethyl-4-aminophenoxy?phenyl?-ben-zene?TTFAPOPB?was obtained by the method of catalytic hydrogenation.The structure of all the intermediate products was characterized by FT-IR,¹H-NMR and elemental analysis.The fluorinated hyperbranched polyimide?FHBPI?with different end groups was prepared by poly-condensation between three different kinds of commercial dianhydride and the prepared triamine monomer.And then,FT-IR,XRD,TGA,DSC and DMA were used to characterize the comprehensive performance of the obtained polyimide films.The results show that the new FHBPI can be dissolved in common organic solvents well;and have good thermal stability no matter in nitrogen?N₂?or in air atmosphere,the temperature at 10%weight loss was between 520.3?and 555.0?under N₂ atmosphere.And the glass transition temperature(T_g1)of the FHBPI films were between 225.50?and 263?.The water contact angle of the films beyond 99°,and the water absorption lower than 0.72%,all of this indicated that the FHBPI films displayed good hydrophobic property.The maximum tensile strength and modulus of the films were achieved 84.22MPa and 1.53GPa.The cutoff wavelength of the films exceeds 425nm,and the transmittance at 800nm was higher than 94.48%,these explain that all the films not only have wonderful ultraviolet shielding performance,and good optical transparency.The dielectric constants of all the films were between 2.69 and 2.92,lower than 3.0,which illustrate favorable dielectric properties.Ternary copoplymerization polyimide?co-PI?was prepared by poly-condensation between BPADA,ODPA and ODA.Then,HAuCl₄ as the raw material for Au NPs,co-PI as the matrix,sodium borohydride as reducing agent,co-PI/AuNPs nanocomposite films was prepared by film casting technology.The XRD and SEM images show that AuNPs had been successfully reduced and well dispersed in co-PI matrix,and no obvious reunion phenomenon.TGA curves illustrate that the thermal decomposition temperature of the composite films is lower than pure co-PI film;however,from the DSC curves and tensile test results,we can see that the mechanical performance and T_g of composite films increased with the loading of AuNPs,and then decreased,the optical load is 0.450%.The transmittance of the composite films declined with the increasing AuNPs loading,but the ultraviolet absorption wavelength of all the films is more than 400nm.So,as UV shielding material,co-PI/AuNPs films have good application prospects in many aspects.Catalytic performance results explain that the Catalytic performance of co-PI/AuNPs films is very good,and is closely relative to the content and distribution state of AuNPs.