Infrared investigation of polyimide film structures

Laius, L. A.

doi:10.1016/0032-3950(74)90248-2

Cited by 5 publications

(2 citation statements)

References 5 publications

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“…This disordered interphase can be considerably thicker if strong chemical interaction occurs between coating and substrate. This has been observed for polyimides on reactive substrates such as copper where its precipitates diffuse as far as 500 A into the PMDA-ODA coating.39 Wavenumbers Figure 9. Reflection infrared spectra in the 1060-1160 cm-1 region obtained for films of various thicknesses on gold.…”

Section: Resultsmentioning

confidence: 68%

Characterization of PMDA-ODA Polyimide Films by External Reflectance Infrared Spectroscopy

Perez¹,

Ren²,

Farris³

et al. 1994

Macromolecules

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Reflectance infrared spectroscopy has been carried out for quantitative structural analysis of polyimide films thinner than lo00 A. Reflection spectra have been simulated for isotropic polyimide films of specific thickness on a metallic substrate. Structural analysis was based on a number of infrared active vibrations particularly sensitive to changes in chain conformation or packing. The structure of these films was compared with that obtained by annealing experiments on free standing films and crystalline powders.For adsorbed films with thicknesses C150 A, very low packing order was found. Frequency shifts in films of varying thicknesses were observed to be sensitive to changes in chain conjugation which are dependent on the coplanarity of rings along the backbone. Utilizing vibrations of known transition moment direction allowed one to characterize the degree of segmental orientation relative to the surface normal of variously prepared films. Spectroscopic data also revealed changes in orientation of the rigid planar structures in PMDA-ODA polyimide with respect to the surface normal upon variation of film thickness. The imide ring, preferentially aligned perpendicular to the surface normal in thin films, changes toward an isotropic orientation distribution. The chain orientation reached a constant value off = -0.28. These spectroscopic studies were corroborated by electron diffraction tilting experiments obtained from flat films lifted from their respective gold substrates.

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Section: Resultsmentioning

confidence: 68%

Characterization of PMDA-ODA Polyimide Films by External Reflectance Infrared Spectroscopy

Perez¹,

Ren²,

Farris³

et al. 1994

Macromolecules

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show abstract

“…Both the 1722 and 738 cm -1 bands show the perpendicular dichroism, and the transition moments are parallel (inplane) for the former and perpendicular (out-of-plane) for the latter to the phthalimide molecular plane. 18,28,[56][57][58][59][60][61] Figure 16c illustrates the changes in the infrared dichroic ratios measured at θ ) 60°upon stepwise annealing for the PI(BPDA/PDA) film (4.3 µm thick). When the phthalimide molecular plane is in 3-D random orientation, the dichroic ratio takes unity.…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Molecular Orientation of Polyimides Induced by Thermal Imidization. 2. In-Plane Orientation

et al. 1996

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The degree of in-plane molecular orientation of various polyimides (PIs) and their precursors, poly(amic acid)s (PAAs), were estimated by measuring the visible dichroic absorption at an incidence angle for a rod-like dye (perylenediimide, PEDI) dispersed in the matrices. The effects of PI chain structure, film thickness, heating rate, and residual solvent on a spontaneous in-plane orientation phenomenon were examined to fully understand the mechanism. All PAA films cast on a substrate showed the low degrees of in-plane orientation of the chain axis, nearly independent of the chain structure. Upon thermal imidization of the PAA films adhered on a substrate, a striking spontaneous in-plane orientation behavior was observed for some PI systems with rigid chains; in contrast to that, some flexible PI systems showed no spontaneous behavior. Cure of the PAA films adhered on a substrate induced the spontaneous orientation even if the films were considerably thick (∼50 μm); in contrast to that, the cure of the free-standing thick film did not. However, upon cure of the free-standing thin films (∼10 μm), the spontaneous orientation behavior was observed. For rigid PI systems in which interchain stacking preferentially occurs, thermal cure of the PAA films on a substrate forms liquid-crystal-like highly oriented regions, and simultaneously, apparent stretching (due to constraint of film contraction during imidization) promotes the molecular orientation further. The mechanism is closely associated with a “cooperative effect” in which the neighboring chains enhance the molecular orientation of each other during cure. In addition, structural changes (orientations of the chain axis and a molecular plane and molecular packing) upon stepwise annealing were followed. Polarized infrared absorption spectra measured at an incidence angle demonstrated that the phthalimide molecular plane in the PI film on a silicon wafer aligns somewhat parallel to the film plane, but no significant orientational and conformational changes occurred upon stepwise annealing.

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Determining the angles between moments of vibratory transitions and the axis of the elementary polyethylene terephthalate unit

Stas’kov¹,

Gusev²

1976

Polymer Science U.S.S.R.

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Infrared investigation of polyimide film structures

Cited by 5 publications

References 5 publications

Characterization of PMDA-ODA Polyimide Films by External Reflectance Infrared Spectroscopy

Characterization of PMDA-ODA Polyimide Films by External Reflectance Infrared Spectroscopy

Spontaneous Molecular Orientation of Polyimides Induced by Thermal Imidization. 2. In-Plane Orientation

Determining the angles between moments of vibratory transitions and the axis of the elementary polyethylene terephthalate unit

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