Synthesis and optical characterization of polyimide-copolysiloxane
Loading...
Date
2019-07
Authors
Chan Pei Wen
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Hyperbranched polyimide (PI) derived from monomer TTA/ODPA and hyperbranched polyimide-co-polysiloxane (PIS) derived from TTA/ODPA/APTMS were successfully synthesized and underwent various characterization to investigate the role of siloxane segment and effect of siloxane content on PI system. These characterization included structural, chemical stability, thermal and optical characterization. The method used to incorporate Si-O-Si segmentsinto the PI backboneschain was through conventional copolymerization method. All synthesized PI films shows yellowish-brownish coloration. The FTIR results showed that the PI and PIS films were fully imidized and the presence of Si-O-Si segments on the PI chain has been successfully proven. The PI and PIS films showed high chemical stablity in acidic, polar, non-polar, protic and aprotic solvents. TGA studies revealed that the Si-O-Si segment reduced the thermal stability of PIS system due to earlier degradation of weak Si-O-Si segment. DSC results showed that no phase transition was observed for all PI films due to insensitiveness of DSC method and the Tg of PI series has exceeded the examined temperature range. DMA results showed that the presence Si-O-Si segment in the PIS reduced the glass transition temperature (Tg) and increased loss modulus (E”) due to flexible Si-O-Si segment able to dissipate high deformation energy. DMA results also revealed that microphase separation was observed in PIS system with higher siloxane content with the presence of two Tg in tan 𝛿 curve. For optical characterization, the presence of Si-O-Si segment increased the transmittance and decreased the refractive index of PI films. In conclusion, the incorporation of siloxane segment into hyperbranched PI backbone chain has improved the processing properties, and enhanced the optical properties without greatly sacrificed its initial properties such as superior thermal stability and chemical resistance.