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The characterization of diacetylene acid Langmuir film and Langmuir-Blodgett film

Shih, Raymond Chuan-Cheng
http://rave.ohiolink.edu/etdc/view?acc_num=case1061473845

Abstract Details

1994, Doctor of Philosophy, Case Western Reserve University, Chemical Engineering.
The Langmuir-Blodgett (LB) process is a unique method of producing uniform, highly ordered monomolecular thin films by transferring the Langmuir monolayer film from an air-liquid interface. This study focused on the characterization of the 10,12-pentacosadiynoic acid (12-8 diacetylene acid) monomolecular films before and after the deposition process. 12-8 diacetylene acid LB film has its special physical and chemical properties, such as sensitivity to light (polymerizes when close packed) and its non-linear optical property. Various methods of characterization were employed so as to follow structure changes between Langmuir films and LB films. A Brewster angle microscope was used to study the Langmuir film of 12-8 diacetylene acid during the compression process on the liquid interface. The different morphologies appearing on various liquid subphases explained the different results from the LB deposition. This study provides evidence and explanation, for the first time, why 12-8 diacetylene acid can only be homogeneous and stable on a liquid subphase with Cadmium ions present. Atomic force microscopy and X-Ray diffraction methods were used to study the Langmuir-Blodgett films on solid substrates. By depositing a two-monolayer film step on the solid substrates, local film thickness can be observed and compared with the X-Ray diffraction results; they were found to be consistent. Molecular-scale images were acquired from the AFM, a highly ordered structure can be clearly observed in the 12-8 diacetylene acid film with an anisotropic oblique unit structure on the surface. The unit cell lattice parameters were consistent throughout all the samples. The polymerized 12-8 diacetylene acid film also appeared to be oriented on the surface along the deposition direction, but the film is very rough, RMS increases to as much as 40 A from several angstroms. Liquid crystal material alignment on such polymerized film was tested, homeotropical alignment was observed. Linear polymerization of 12-8 diacetylene acid monomer film can be obtained by exposing the monolayer samples to a polarized UV light source. X-Ray scattering techniques were used on the monomer, isotropically polymerized, and linearly polymerized diacetylene films along different direction. By comparing the difference of the scattering patterns, we can prove that the film has organized by this technique with the π-conjugate bonds ribbon aligned perpendicular to the polarization axis
J. Mann (Advisor)
215 p.
Engineering, Chemical
Diacetylene acid; Langmuir film; Langmuir-Blodgett process

Recommended Citations

Citations

  • Shih, R. C.-C. (1994). The characterization of diacetylene acid Langmuir film and Langmuir-Blodgett film [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1061473845

    APA Style (7th edition)

  • Shih, Raymond. The characterization of diacetylene acid Langmuir film and Langmuir-Blodgett film. 1994. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1061473845.

    MLA Style (8th edition)

  • Shih, Raymond. "The characterization of diacetylene acid Langmuir film and Langmuir-Blodgett film." Doctoral dissertation, Case Western Reserve University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061473845

    Chicago Manual of Style (17th edition)

case1061473845
539
© 1994, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.