Low-Stress Hyperbranched Polymer/Silica Nanostructures Produced by UV Curing, Sol/Gel Processing and Nanoimprint Lithography

Nanocomposite materials based on a HBP and silica are produced using either a dual-cure sol/gel and photopolymerization process or by mixing silica nanoparticles with the HBP. In both cases the conversion of the HBP is independent of composition and obeys a time-intensity superposition with power-law dependence on UV intensity. Optimization of the dual-cure process leads to transparent sol/gel composites with ultrafine structures. These materials systematically outperform the particulate composites, including an increase of the glass transition temperature of 63 degrees C and a process-induced internal stress as low as 2.5MPa. Nano-sized gratings are produced from the sol/gel composites by low-pressure UV nanoimprint lithography.