Intermolecular interactions between sol–gel-derived random-structure oligomeric silsesquioxanes and a diazonaphthoquinone derivative

Abstract

Oligomeric silsesquioxanes (Oligo-SQs) with random structures featuring phenyl (Ph) groups or both Ph and methyl (Me) groups as their substituents were synthesized by the sol–gel method. The ratio of Ph and Me groups controlled the molecular weights and branching in the Oligo-SQs. Branching increased as the molecular weight increased (when the alkaline dissolution rates of all Oligo-SQs adjusted to ∼40 nm s−1). A diazonaphthoquinone (DNQ) derivative was added to the Oligo-SQs to impart positive photosensitivity. A Ph content ratio of over 50 mol% was found to be necessary for the Oligo-SQs to exhibit DNQ compatibility and good patterning performance. Infrared absorption spectroscopy analysis and density functional theory calculations indicated the formation of novel aromatic siloxane DNQ aggregates upon hydrogen bonding between hydroxyl group domains in the Oligo-SQ (formed by hydroxyl groups bonded to Si on adjacent Ph moieties) and the DNQ derivative, which adopts only one of its possible resonance structures.