Photodegradation of polyimides. 6. Effect of donor-acceptor groups on the photooxidative stability of polyimides and model compounds

Creed, David; Hoyle, Charles E.; Subramanian, P.; Nagarajan, R.; Pandey, Chandra; Anzures, Edgardo T.; Cane, Kevin M.; Cassidy, Patrick E.

doi:10.1021/ma00081a031

Cited by 17 publications

(9 citation statements)

References 1 publication

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“…The transient absorption spectra in the presence of N -methylphthalimide (10 mM) during the nanosecond/picosecond two-color two-laser flash photolysis are shown in Figure . In the presence of N -methylphthalimide, the absorption band of the N -methylphthalimide radical anion, at ∼420 nm, was observed after the second laser excitation …”

Section: Resultsmentioning

confidence: 99%

Intermolecular Electron Transfer from Excited Benzophenone Ketyl Radical

et al. 2006

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The electron transfer from the benzophenone ketyl radical in the excited state (BPH(.-)(D(1))) to several quenchers (Qs) was investigated using nanosecond/picosecond two-color two-laser flash photolysis and nanosecond/nanosecond two-color two-laser flash photolysis. The electron transfer from BPH(.-)(D(1)) to Qs was confirmed by the transient absorption and fluorescence quenching measurements. The intermolecular electron-transfer rate constants were determined using the Stern-Volmer analysis. The driving force dependence of the electron-transfer rate was revealed.

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Section: Resultsmentioning

confidence: 99%

Intermolecular Electron Transfer from Excited Benzophenone Ketyl Radical

et al. 2006

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“…The fluorine atom has a high electronegativity, whereas the CF combination has a high binding energy and a low polarizability. Thus, fluorine‐containing polyimides have high potential as materials in electronic applications 10, 11. Furthermore, the fractional free volume (FFV), which is the standard of the space between polymers segments, increases with the introduction of substituents that have a high volume among atoms, such as fluorine atoms.…”

Section: Introductionmentioning

confidence: 99%

Relationship between the gas transport properties and the refractive index in high‐free‐volume fluorine‐containing polyimide membranes

Sato

Ose

Miyata

et al. 2011

J of Applied Polymer Sci

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The refractive index and gas transport properties (i.e., permeability, diffusivity, and solubility) in the 2,2 0bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA)-based polyimides were systematically investigated in terms of their polymer fractional free volumes (FFVs). The permeability and diffusion coefficients of the 6FDA-based polyimide membranes to hydrogen, oxygen, nitrogen, methane, and carbon dioxide were correlated with their FFVs, which were estimated with van Krevelen's group contribution method. Linear correlations were also observed between the gas transport properties and the refractive index of these polyimides. We described FFV as a function of the refractive index based on the Lorentz-Lorenz equation. Linear correlations were observed between their refractive-index-based FFVs and the gas permeability, diffusivity, and solubility coefficients of these 6FDA-based polyimides membranes. However, the FFVs of the 6FDA-based polyimides calculated from refractive index were 1.16-1.37 times larger than their FFV values. This FFV was dependent on the free-volume space and optical factors, such as the refractive index and molar refraction, which affected the electronic structure and the interactions between the gas molecules and the polymer segments.

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“…In 1990s, a series of pioneering work on the investigation of photo-degradation of PI films, especially the fluorinated PI films, were carried out in Hoyle’s group via spectral, viscometric, chromatographic, and weight loss methodologies [ 10 , 11 , 12 , 13 , 14 , 15 ]. The experimental results based on the systematic analysis for the photodegradation behaviors of various PI films demonstrated that the photodegradation behavior of PI films is closely related to the electronic properties of the substituents in their molecular structure.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Ultraviolet Light Resistance of Colorless and Transparent Semi-Alicyclic Polyimide Nanocomposite Films via the Incorporation of Hindered Amine Light Stabilizers for Potential Applications in Flexible Optoelectronics

Wei

He²,

Yuan³

et al. 2022

Polymers

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Optically transparent polymer films with excellent thermal and ultraviolet (UV) resistance have been highly desired in advanced optoelectronic fields, such as flexible substrates for photovoltaic devices. Colorless and transparent polyimide (CPI) films simultaneously possess the good thermal stability and optical transparency. However, conventional CPI films usually suffered from the UV exposure and have to face the deterioration of optical properties during the long-term service in UV environments. In the current work, the commercially available hindered amine light stabilizers (HALS) were tried to be incorporated into the semi-alicyclic CPI matrix with the aim of enhancing the UV exposure stability. For this target, a CPI-0 film was first prepared from hydrogenated pyromellitic dianhydride (HPMDA) and 2,2′-dimethylbenzidine (DMBZ) via a one-step polycondensation procedure. Then, the commercially available HALS were incorporated into the CPI-0 (HPMDA-DMBZ) film matrix to afford four series of CPI/HALS composite films. Experimental results indicated that the Tinuvin® 791 HALS showed the best miscibility with the CPI-0 film matrix and the derived CPI-D series of composite films exhibited the best optical transmittances. The CPI-D nanocomposite films showed apparently enhanced UV exposure stability via incorporation of the 791 additives. For the pristine CPI-0 film, after the UV exposure for 6 h, the optical properties, including the transmittance at the wavelength of 350 nm (T350), lightness (L*), yellow indices (b*), and haze obviously deteriorated with the T350 values from 55.7% to 17.5%, the L* values from 95.12 to 91.38, the b* values from 3.38 to 21.95, and the haze values from 1.46% to 9.33%. However, for the CPI-D-10 film (791: CPI-0 = 1.0 wt%, weight percent), the optical parameters were highly maintained with the T350 values from 61.4% to 53.8%, the L* values from 95.46 to 95.36, the b* values from 1.84 to 1.51, and the haze values from 0.69% to 3.34% under the same UV aging conditions.

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Photodegradation of polyimides. 6. Effect of donor-acceptor groups on the photooxidative stability of polyimides and model compounds

Cited by 17 publications

References 1 publication

Intermolecular Electron Transfer from Excited Benzophenone Ketyl Radical

Intermolecular Electron Transfer from Excited Benzophenone Ketyl Radical

Relationship between the gas transport properties and the refractive index in high‐free‐volume fluorine‐containing polyimide membranes

Enhancement of Ultraviolet Light Resistance of Colorless and Transparent Semi-Alicyclic Polyimide Nanocomposite Films via the Incorporation of Hindered Amine Light Stabilizers for Potential Applications in Flexible Optoelectronics

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