Nanostructured ultra thin films by covalent molecular assembly in supercritical carbon dioxide

Abstract

With the objective of developing environmentally benign processing techniques for fabricating robust, nano-structured, functional film structures, this Ph.D thesis is focused on formation of ultrathin films by covalent molecular assembly using supercritical carbon dioxide (SCCO2) as the processing solvent. A comparative analysis of molecular assembly of oligoimide with covalent bonding using conventional and supercritical solvents has been performed. The effect of the nature of the reactive substrate surface (anhydride-terminated versus amine-terminated) on the molecular assembly process and the properties of the resulting film when supercritical carbon dioxide is deployed as the solvent vehicle have been investigated. Formation of mono and bimetallic nanoparticles in immobilized dendrimers and the application of the composite films in tribology are demonstrated. Apart from showing the feasibility of layer-wise molecular assembly with interlayer covalent bonding, this work demonstrates a promising alternative to conventional molecular assembly employing organic solvents.