title: Application of direct covalent molecular assembly in the fabrication of polyimide ultrathin films.
abstract: Ultrathin films were fabricated using synthesized hydroxyl polyimide (HPI) in a layer-by-layer fashion on amine-terminated substrates of silicon, quartz, and gold. The interlayer linkages were established by using terephthaloyl chloride as a bridging agent to form ester groups between HPI layers. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy, atomic force microscopy, ellipsometry, and electrochemical impedance spectroscopy were employed to study the interfacial chemistry, stepwise growth, morphology, thickness, optical property, and insulation behavior of the assembled film. The films show excellent stability and strength, which can be attributed to the covalent interlayer linkage.
authors.affiliation: Centre for Nanoscale Engineering, Department of Chemical and Biomolecular Engineering, Blk E5, 4 Engineering Drive 4, National University of Singapore, Singapore 117576.
authors.forename: F
authors.initials: F
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Jia
authors.forename: M P
authors.initials: MP
authors.lastname: Srinivasan