Interfacial Chemistry of Titanium Films Deposited on PMDA-ODA Polyimide

Abstract

Titanium was evaporated onto PMDA-ODA polyimide surfaces at room temperature up to total thicknesses of about five monolayers. The polyimide backbone is ruptured at both the oxygen ether linkage in the ODA and at the nitrogen imide linkage. The first fraction of a monolayer reacts with oxygen atoms in both the carbonyl and ether functionalities, and forms a mixed oxide with titanium predominantly in the Ti⁺³ oxidation state. Near one monolayer coverage, a carbide or mixed oxy-carbide species forms. Above one monolayer, nitrogen is strongly attacked and ~50% of the nitrogen reacts with titanium. The deposited titanium begins to take on metallic character only after the coverage has reached several monolayers. Heating at 575 K causes additional reaction. Scanning tunelling microscopy images obtained in air following heating show that the composite surface is substantially roughened.

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