Fourier Transform Infra Red Observation of the Orientation of Dipolar Urea Bonds in Polyurea during Corona Poling

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Abstract
Polyurea thin films were prepared using 4,4-diaminodiphenyl methane (MDA) and 4,4-diphenyl methane diisocyanate (MDI), by vapor deposition polymerization. Polyureas include urea bonds which contain NH and CO dipolar groups. The dipole orientation which was caused by corona poling was observed by Fourier Transform Infra-Red [FT-IR] reflectance. In diode corona poling, the dipoles are aligned best in the area directly below the needle electrode, with the degree of dipole orientation decreasing in proportion to increasing distance from this electrode. In triode corona poling, a grid electrode is set up between the needle electrode and planar electrode, and orientation is accomplished uniformly over the entire surface. Contrary to this assumption, however, we found, through FT-IR mapping analysis, that dipole orientation follows the form of a net mesh structured like a grid electrode.