Deposition of polyimide precursor by resonant infrared laser ablation |
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Authors: | NL Dygert AP Gies KE Schriver RF Haglund Jr |
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Institution: | (1) Interdisciplinary Program in Materials Science, Vanderbilt University, Nashville, TN 37235, USA;(2) Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA;(3) Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA;(4) W.M. Keck Foundation Free Electron Laser Center, Vanderbilt University, Nashville, TN 37235, USA |
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Abstract: | We report the successful deposition of a polyimide precursor using resonant infrared laser ablation (RIR-LA). A solution of
poly(amic acid) (PAA) dissolved in N-methyl-2-pyrrolidinone (NMP), the melt processable precursor to polyimide, was frozen
in liquid nitrogen for use as an ablation target in a high-vacuum chamber. Fourier transform infrared spectroscopy was used
to determine that the local chemical structure remained unaltered. Gel permeation chromatography demonstrated that the transferred
PAA retained its molecular weight, showing that RIR-LA is able to transfer the polymer intact, with no detectable chain fragmentation.
These results are in stark contrast to UV-processing which degrades the polymer. After deposition the PAA may be removed with
a suitable solvent; however, once the material has undergone cyclodehydration it forms an impenetrable three-dimensional network
associated with thermosetting polymers. The transfer of uncured PAA precursor supports the hypothesis that RIR-LA is intrinsically
a low temperature process, because the PAA is transferred without reaching the curing temperature. The RIR-LA also effectively
removes the solvent NMP from the PAA, during both the ablation and deposition phases; this is a necessary step in generating
PI films.
PACS 41.60.Cr; 78.30.Jw; 81.15.Fg |
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Keywords: | |
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