Synthesis And Property Investigation Of Seleniumcontaining Polyimides With High Refractive Index

Optical materials have been proved as the important materials for widely applications.Higher requirement has been raised for these materials with the development of electronic and information technology.Normally,various parameters were important for such materials,such as refractive index,Abber number,dispersion,transmittance,mechanical property,hygroscopicity and thermostability.Among them,refractive index and Abber number were regarded as the most important factors.Traditional polymers exhibit relatively low refractive indices,often in the range of 1.30-1.70.Those with refractive index higher than 1.70 are called high refractive index polymers(HRIPs)and with the applications in optical and optoelectronic devices.HRIPs showed light weight,tenacity and high RI,which have been recognized as more and more advantages in optical devices.Thus,developing polymer resin with high RI materials have become hot point to research.At the same time,polyimides(PIs)show excellent performances in these fields of thermal,mechanical,optical and electricity,and are widely used as optical films,gas separation membranes,photoresist,polyelectrolyte and soft electronic devices,are called "golden films".Therefore,high performance PIs are regarded as good model material to design high refracetive index(RI)polymers.It showed that the introducing of sulfur into PIs could improve RI of PIs in range of 1.680-1.769 and maintaining excellent thermal stability,low dielectric constant,and outstanding mechanical properties.According to Lorentz-Lorenz equation,increasing of molar volume and molar refractivity would be useful to improve therefractive index.Selenium as the analog to sulfur showed much higher molar refraction even than that of sulfur,i.e.,[R] = 11.17 of selenide and [R] = 7.69 of sulfur.Thus,introducing selenium into PI would evidently enhance its RI value.Based on such consideration,here in,following works have been carried out:(1).Commercial 4,4?-oxydianiline(ODA)and pyromellitic dianhydride(PMDA)were used to synthesize polyimide(Kapton?)(PI-1-1)with the "two steps" mothed.Replaced PMDA with OPDA to obtain another basic polyimide(PI-1-2).Bis(4-aminophenyl)selenide(BAPSe)containing phenyl selenide moiety was synthesized,and then polymerized with PMDA and OPDA obtaining two selenium-containing PIs,respectively,named PI-1-3 and PI-1-4.In addition,alkane ring dianhydrides such as 1,2,4,5-cyclohexanetetracarboxylic dianhydride(HPMDA)and cyclobutane 1,2,3,4-tetracarboxylic dianhydride(CBDA)were also used for synthesizing polyimides.The results showed that these alkane ring containing polyimides exhibited low thermostability and degraded at around 200?.RI of four PIs such as PI-1-1,PI-1-2,PI-1-3 and PI-1-4 were tested,and showing RI value 1.706,1.705,1.728 and 1.808,which Abbe number showed 15.83,18.07,12.44 and 18.10,respectively.Obviously,from these results,it showed that introducing of selenium into polymer can enhance its RI value.(2).In order to increase the content of selenium,based of preamble which proved,introducing selenium to dianhydride would be expected.After consideration,novel 1,1?-Bis(4-(3,4-dicarboxylbenzoyloxy)phenyl)selenide dianhydride(BDPSD)was synthesized,and 1,1?-Bis(4-(3,4-dicarboxylbenzoyloxy)phenyl)ester dianhydride(BDPED)was also synthesized as contrast.Four PIs were designed and synthesized via amine-dianhydride polycondensation of one of two diamines,i.e.,ODA and BAPSe,with one of two dianhydrides,i.e.,BDPSD and BDPED,named PI-2-1,PI-2-2,PI-2-3 and PI-2-4.FT-IR was empolyed to explain extent of reaction,and RI of polymers are 1.763,1.953,1.903,1.968,which Abbe number showed 19.7,24.6,8.7 and 7.2,respectively.These PIs were measured on solubleness and optical property with phenomenon and UV-vis,further,proved experimental result by theoretical calculation.In the end,antireflection of four PIs was further researched.The reflectivity of textured silicon wafer declined from 22% to 11%.