Synthesis and characterization of novel fluorosilicone polyimides with high optical transparency

Abstract

To overcome insoluble and low transmittance of the traditional polyimides (PIs), two kinds of novel fluorosilicone PIs were prepared. First, 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene, compound 3a, and 4,4′-bis(4-amino-2-trifluoromethylphenoxy)diphenyl ether, compound (3b), with 2-chloro-5-nitrobenzotrifluoride and p-hydroquinone or 4,4′-dihydroxydiphenyl ether were prepared. Second, hydrosilylation of nadic anhydride (NA) with 1,1,3,3-tetramethyldisiloxane (TMDS) yielded 5,5′-(1,1,3,3-tetramethyl-1,3-disiloxanediyl) bisnorbornane-2,3-dicarboxylic anhydride, compound (4). Initially, the conditions of the synthesis reaction such as reaction temperature, catalyst dosage, molar ratio of TMDS/NA, and reaction time on yield of compound 4 by the single factor approach were studied. The optimal reaction conditions were reaction temperature: 90°C, catalyst dosage: 1 ml (Pt% = 0.37%), molar ratio of TMDS/NA: 1/1.8, and reaction time: 3 h. The yield was 74.6%. Finally, two kinds of new organosoluble, light-colored, and good thermal stable fluorosilicone PI compounds (5a-5b) were synthesized from compounds 3a-3b and 4 and 4,4′-hexafluoroisopropylidenediphthalic anhydride), prepared through a typical two-step polymerization method. The solubility of the novel fluorosilicone PI films of compounds 5a-5b and the traditional PI film (4,4′-diaminodiphenyl ether (ODA)-biphenyltetracarboxylic dianhydride, DIY) were contrasted. The result showed that the fluorosilicone PI films have good solubility. These PIs were soluble in amide polar solvents and even in less polar solvents. The glass transition temperatures of compounds 5a-5b were 229.1 and 186.7°C and the 5% and 10% weight-loss temperatures were 519.8°C and 539°C, respectively. These films had cutoff wavelengths of 331.8 and 318.6 nm. Due to these properties, these PIs could be used as aerospace, photoelectric, and microelectronic materials.