Photocatalytic Surface Initiation for Area-Selective Chemical Vapor Deposition of Polymer Thin Film

Abstract

Nonlithographic patterning of polymer thin films enables various applications spanning from soft electronics to biomedical engineering. Developing area-selective deposition (ASD) for polymers could achieve self-aligned polymer growth, fostering the generation of complex nanostructures and device configurations with enhanced precision and versatility. However, due to the rapid radical propagation in chain reactions, achieving area-selective radical polymerization in all-dry processes still represents a huge challenge. Here, we report a photocatalytic surface-initiated chemical vapor deposition method. Localized radical generation on the TiO 2 surface enabled ASD of a poly(glycidyl methacrylate) (pGMA) thin film. Increasing hydroxyl groups and eliminating Ti(III) defects on the TiO 2 surface by the O 2 plasma pretreatment were found to be crucial to promote the photocatalytic initiation efficiency. Moreover, we obtained area selectivity of up to 92.2% on prepatterned TiO 2 /SiO 2 substrates with pGMA film thickness over 10 nm on TiO 2 . Our work offers placement control over chain-growth polymers, providing new opportunities for bottom-up nonlithographic nanofabrication.