Electrophoretic deposition of polyimides

Figure 3. Reaction cycle for electrophoretic deposition of a polyimide.

Contamination of the polyimide with metal ions is a serious concern with respect to the thermal and electrical properties of the finished films. Also, the ability to obtain uniform film thicknesses over irregular surfaces is one of the key advantages of electrophoretic deposition. It was these considerations that provided the impetus for the work reported in this paper. 

General. Commercially available polyimides were used (see Table I). Solvents were reagent grade or better and were used as received. 1-Methylpiperazine (Aldrich Chemical Co.) was > 99.9% pure. Lactic acid (Aldrich) was reduced to 50% by weight in water and refluxed for an hour to hydrolyze esters. IR spectra were recorded on a Perkin-Elmer Model 1430 spectrometer. Thermogravimetric analysis was done on a P-E System 4/TGS-2 instrument. Size exclusion chromatography was done on a Perkin-Elmer Series 3B equipped with the LC-75 spectrophotometric detector. The column set used consisted of P-E 0258-2134, 2133, and 2131 columns (pore sizes 103, 104, and 106 A, respectively). For electrophoretic deposition experiments, a TCR Power Supply (Electronic Measurement Systems Inc.) was used. Temperatures are reported in °C throughout. 

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