Absorption, Fluorescence, and Thermal Properties of Transparent Polyimides Based on Cyclobutanetetracarboxylic Dianhydride

Abstract

ABSTRACT:Ultraviolet/visible absorption spectra and fluorescence spectra of transparent polyimides derived from 1,2: 3,4-cyclobutanetetracarboxylic dianhydride (CBDA) with an aromatic diamine, 4,4'-diaminodiphenylmethane (DPM), a fluorinated diamine, 2,2-bis(4-diaminodiphenyl)hexafluoropropane (6FdA), and an alicyclic diamine, 4,4'-diaminodicyclohexylmethane (DCHM) were investigated, compared with their model compounds. Both monomer and excimer fluorescence were observed in concentrated CH2Cl2 solution of model compounds, suggesting head to tail intermolecular overlap structures at the excited state. All polyimide films derived from CBDA showed high transparency in the visible region, i.e., no absorption tail was found above 375 nm. Especially, PI(CBDA/DCHM) showed the highest transparent property with almost no absorption above 310nm. Absorption shoulders at 235nm of PI(CBDA/DPM) and PI(CBDA/6FdA) are due to the absorption of phenylene groups in the diamine moieties. The fluorescence spectra of all polyimide films studied showed the existence of ground-state complexes. Their excitation wavelength dependence would be due to the existence of various conformations of packing structure. The glass transition temperatures, T 8 , of these polyimides based on CBDA lie in the region of 277°C to 360°C. These polyimides have decomposition temperatures around 450°C under deaerated conditions.

Dielectric Spectroscopy of Polyimide Films Treated by Nanosecond High Voltage Pulsed Driven Electrical Discharges in Water

“…The strength of these CT complexes depends on the electron affinity of the anhydride moiety and the ionization potential of the diamine moiety. [26,27] The electron withdrawing ability of the 6F groups serve to increase the electron affinity of the dianhydride and lead to a stronger CT complexes. The occurrence of such a process is consistent with the observed increase of the CF 3 peak for 20 min of exposure [16] and a gradual increase of the relative permittivity at longer treatment times (Figure 1b).…”

Recent Trends on Transparent Colorless Polyimides with Balanced Thermal and Optical Properties: Design and Synthesis

“…They also reported the synthesis of CBDA‐based PIs with various aromatic amines (e.g., ODA, diaminodiphenylmethane, 2,2‐bis[4‐(4‐aminophenoxy)phenyl]‐propane, etc.) which exhibited high optical transparency (especially PI from CBDA‐ODA), favorable mechanical robustness, low CTE, high T g , and thermal stability, whereas their solubility in common organic solvents was limited when rigid diamines were adopted . Alkyl/phenyl/halogen substituted CBDAs were synthesized by the light‐induced dimerization of a substituted maleic anhydrides by Ishikawa et al .…”

“…which exhibited high optical transparency (especially PI from CBDA-ODA), favorable mechanical robustness, low CTE, high T g , and thermal stability, whereas their solubility in common organic solvents was limited when rigid diamines were adopted. [76][77][78][79]127] Alkyl/ phenyl/halogen substituted CBDAs were synthesized by the light-induced dimerization of a substituted maleic anhydrides by Ishikawa et al [132] Another relatively less explored cycloalicyclic dianhydride is 1,2,4-tricarboxyl-3-methylcarboxyl cyclopentane dianhydride (CPDA). It was obtained after the dehydration of the l,2,3,4-cyclopentanetetracarboxylic acid which again was synthesized by oxidizing a Diels-Alder adduct of cyclopentadiene and maleic anhydride with nitric acid, followed by neutralization with a base.…”

Optical properties of polyimides films treated by nanosecond pulsed electrical discharges in water

“…[10][11][12] On the other hand, fluorinated PIs have attracted much attention owing to the decrease in the degree of CT interaction caused by CF 3 -substituted diamines. [12][13][14] The introduction of hexafluoropropanedianhydride (6FDA) to the polyimide main chain derived from dianhydrides weakens the intermolecular CT owing to the bulky substituent group -C(CF 3 ) 2 -, which prevents the molecular packing of polyimide films. 14) In the case of cobalt-modified PIs, note that cobalt(II) chloride groups may also diffuse preferentially through amorphous regions, forming charge transfer complexes.…”