A colorless semi-aromatic polyimide derived from a sterically hindered bromine-substituted dianhydride exhibiting dual fluorescence and phosphorescence emission

Abstract

A colorless and thermally stable polyimide film exhibiting dual fluorescence and phosphorescence emission promising for solar spectral down-converters.

Photoluminescence Properties of Novel Fluorescent Polyimide Based on Excited State Intramolecular Proton Transfer at The End Groups

“…6FDA dianhydride have been widely used for PI synthesis because it endows the PIs with low dielectric constant, good solubility in polar solvents, and high gas permeability. In particular, 6FDA-based PIs exhibit high optical transparency because of its low electron affinity (E A ) which reduces intra-and interchain charge transfer (CT) transition [6]. Figure 2 displays the UV/Vis absorption spectra of 6FDA-based PI films, in which the absorbance was normalized by the film thickness.…”

“…Since the electron transition of 6FDA/DCHM PI by UV light is assigned to non-fluorescent n−π* transition [6], the obvious green fluorescence should be emitted from the 3HPA end group. The excitation and emission peaks of the 6FDA/DCHM/3HPA PIs with different r ratios are similar to those of 3HPA model compound as reported previously [1].…”

“…Polyimides (PIs) are a group of condensation polymers which have high thermal stability, good mechanical strength, excellent chemical stability, low dielectric constant, and low thermal expansion [1][2][3][4][5][6][7][8]. Thus, PIs have been widely used as insulating interlayer films in microelectronic industry and thermal controlling films in aerospace industry.…”

Synthesis and properties of novel colorless and thermostable polyimides containing cross‐linkable bulky tetrafluorostyrol pendant group and organosoluble triphenylmethane backbone structure

“…Fourier transform infrared (FTIR) spectra of the monomers were measured on a Nicolet Impact 380 FTIR spectrometer by KBr pressed disc method, while FTIR spectra of the polymers were measured on a FTIR-650 liquid FTIR spectrometer of Tianjin Gangdong Technology Development Co. Nuclear magnetic resonance (NMR) spectra were performed on a Bruker 400 AVANCE III spectrometer operating at 400 MHz for 1 H NMR, 376 MHz for 19 F NMR and 101 MHz for 13 C NMR using dimethyl sulfoxide-d 6 (DMSO-d 6 ) as solvent. The chemical shifts relative to tetramethylsilane for 1 H NMR and 13 C NMR, and CFCl 3 for 19 F NMR as internal reference are reported on the ppm scale. MALDI-TOF-MS spectrometry adopted a Brook Dalton Autoflex tof/tofIII type matrix-assisted laser desorption-tandem time-of-flight mass spectrometer.…”

“…Common methods include the introduction of alicyclic structures, fluorine atoms, bulky substituents, twisted asymmetric structures and flexible links, and so forth, which could depress the close packing of polymer chains and disrupt the conjugation between the molecular chains to reduce the formation of CTC, and thereby increasing the light transmittance of the film. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] However, the molecular structure designs that are in favor of optical transparency usually impair the thermal performance of the materials to some extent. For example, Zhou et al synthesized a novel monomer trans-1,4-bis (2,3-dicarboxyphenoxy) cyclohexane dianhydride with alicyclic structure, which reacted with a variety of diamines to prepare a series of PIs.…”