Analysis of Rubbed Polyimide Films by Polarized Infrared Spectroscopy:   Effects of Immersion in Organic Solvents

Hasegawa, Ray; Mori, Yasushi; Sasaki, Hideyuki; Ishibashi, Mitsuru

doi:10.1143/jjap.35.3492

Cited by 17 publications

(9 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To study how rubbing affects the polymer surface structure, a number of techniques have been used with varying degrees of success. Ellipsometry [6] and infrared spectroscopy [7] can measure rubbing-induced anisotropy in the surface region of a polymer film, but are incapable of probing the real surface because of their lack of surface specificity. Atomic force microscopy [8] can provide images of rubbed polymer surfaces although the spatial resolution may be limited.…”

Section: Department Of Physics University Of California Berkeley Cmentioning

confidence: 99%

Sum-Frequency Vibrational Spectroscopic Study of a Rubbed Polymer Surface

et al. 1999

View full text Add to dashboard Cite

Sum-frequency vibrational spectroscopy has been used to probe the chain orientation of polyvinyl alcohol at the surface after rubbing. The distribution function of the chain orientation is determined quantitatively. The orientational order parameter of the chains deduced from the distribution matches well with that of a liquid crystal monolayer deposited on the polymer, proving that the polymer surface can align a liquid crystal film through orientational epitaxy. [S0031-9007(99)09202-9] PACS numbers: 68.35.Bs, 42.65.Ky, 78.30.Jw Among modern strategic materials, polymers have become increasingly important in our daily life. In many applications, polymer interfaces play a pivotal role. Often it is the orientation and conformation of molecular units at a polymer surface that determine the polymer interfacial properties. For example, surface molecular orientation directly affects adhesion of a polymer to metals or semiconductors, which is vital to modern electronic devices and systems [1]. Surface molecular conformation of a biopolymer, such as protein, DNA, and RNA, strongly influences binding of ligands to a substrate and hence the enzymatic function of the biopolymer [2]. A polymer surface with oriented polymer chains could serve as a template for growing highly ordered polymeric or organic crystals superb in mechanical, electrical, thermal, or optical properties [3]. As a more specific case, rubbed polymer films have long been used in the liquid crystal display industry as substrates for obtaining the desired liquid crystal (LC) bulk alignment. Rubbing presumably modifies the polymer surface structure, and then aligns the LC [4,5]. To study how rubbing affects the polymer surface structure, a number of techniques have been used with varying degrees of success. Ellipsometry [6] and infrared spectroscopy [7] can measure rubbing-induced anisotropy in the surface region of a polymer film, but are incapable of probing the real surface because of their lack of surface specificity. Atomic force microscopy [8] can provide images of rubbed polymer surfaces although the spatial resolution may be limited. Near-edge x-ray absorption fine structure spectroscopy [9] can probe a surface layer of 1 nm thick and yield information on the orientational order parameter of a rubbed polymer surface.Recently, sum-frequency generation (SFG) vibrational spectroscopy has been demonstrated to be an effective surface analytical probe [10]. As a second-order nonlinear optical process, it is forbidden in media with inversion symmetry, but allowed at interfaces where the inversion symmetry is necessarily broken. Therefore it is particularly sensitive to the interfacial structure between two centrosymmetric media. When used to probe surface molecular orientation, it can provide information not only on the average molecular orientation and order parameter but also on the orientational distribution. We report here application of this technique to the study of surface alignment of polymer chains by rubbing. We take polyvinyl alcohol (PVA, ͓-C...

show abstract

Section: Department Of Physics University Of California Berkeley Cmentioning

confidence: 99%

Sum-Frequency Vibrational Spectroscopic Study of a Rubbed Polymer Surface

et al. 1999

View full text Add to dashboard Cite

show abstract

“…The area of the peaks at 1723 and 1501 cm −1 in the difference spectrum can be used to estimate the degree of the orientation of the polymer chains 12. We used the two strong peaks in the difference spectrum to measure the degree of orientation, one at 1723 cm −1 which shows a positive value and one at 1501 cm −1 which shows a negative value by the following equations: Here, A ∥ is the absorbance when the polarization vector is parallel to the PUV irradiation direction or rubbing direction, and A ⟂ , the absorbance when the polarization vector is perpendicular to the PUV irradiation direction or rubbing direction.…”

Section: Resultsmentioning

confidence: 99%

Studies on the photodegradation of polarized UV‐exposed PMDA–ODA polyimide films

West

2002

J of Applied Polymer Sci

View full text Add to dashboard Cite

Polarized Fourier transform infrared (FTIR) and ultraviolet-visible (UV-VIS) spectroscopy were used to investigate the photodegradation direction of polarized UV (PUV)-irradiated polyimide (PI) films based on pyromellitic dianhydride (PMDA) and 4,4Ј-oxydianiline (ODA). PI films strongly absorb below 350 nm, resulting in a photochemical reaction of the PI. PUV irradiation of the PI film caused a decrease of all existing peaks and formation of new peaks at 3258, 1748, and 1710 cm Ϫ1 in the IR, due to degradation of the PI molecules. The preferential degradation of PI molecules parallel to the PUV irradiation direction results in the predominant orientation of the remaining PI molecules perpendicular to the PUV irradiation direction. But rubbing of the PI films induced orientation of the PI molecules parallel to the rubbing direction.

show abstract

“…This difference spectrum is positive at 1721cm-', and negative for the other peaks, clearly supporting perpendicular orientation of the PI chains after PUV irradiation. The area of 1721cm-' and 1503cm-' peaks in the difference spectrum can be used to estimate the degree of the orientation of the polymer chains [26]. We used the two strong peaks in the difference spectrum to measure the degree of orientation, one at 1721 cm-' which shows positive and one at 1503cm-' which shows negative value by the following equations.…”

Section: ( C ) Molecular Orientation Of the Puv Irradiated Pimentioning

confidence: 99%

Infrared Spectroscopic Studies of the Mechanism of Orientation of Polarized UV-exposed Polyimide Films for Liquid Crystal Alignment

West²

1998

Molecular Crystals and Liquid Crystals Science and Technology.

View full text Add to dashboard Cite

Polarized Fourier transform infrared (FTIR) and ultraviolet-visible (UV-VIS) spectroscopy were used to investigate the mechanism of liquid crystal alignment on polarized UV (PUV) irradiated polyimide (PI) films. PI films strongly absorb below 320nm resulting in photochemical reaction of the PI. PUV irradiation of the PI film caused decrease of all the peak intensities in the IR, except the newly formed 1396cm-I peak, due to degradation of the PI molecules. The preferential degradation of PI molecules parallel to PUV irradiation direction results in the predominant orientation of the remaining PI molecules perpendicular to the PUV irradiation direction. But the rubbing of the PI films induced reorientation of the PI molecules parallel to the rubbing direction.

show abstract

Analysis of Rubbed Polyimide Films by Polarized Infrared Spectroscopy: Effects of Immersion in Organic Solvents

Cited by 17 publications

References 13 publications

Sum-Frequency Vibrational Spectroscopic Study of a Rubbed Polymer Surface

Sum-Frequency Vibrational Spectroscopic Study of a Rubbed Polymer Surface

Studies on the photodegradation of polarized UV‐exposed PMDA–ODA polyimide films

Infrared Spectroscopic Studies of the Mechanism of Orientation of Polarized UV-exposed Polyimide Films for Liquid Crystal Alignment

Contact Info

Product

Resources

About