Photodegradable Polycaprolactone-Urethane Enabling Dual-Tone Micropatterning for Sustainable Microfabrication

Abstract

Micropatterning underpins applications in bioelectronics, photonics, and lab-on-a-chip systems; however, current dual-tone photoresists are predominantly nondegradable, limiting their sustainability and biocompatibility. Here, we present photodegradable poly(caprolactone-urethane) (PCLU) photoresists incorporating o-nitrobenzyl (oNB) moieties as a novel dual-tone system. By tuning the composition of the polycaprolactone (PCL) units, oNB diol units, and diisocyanate linkages, the resulting polymers exhibit dose-dependent solubility under 365 nm irradiation, enabling both positive- and negative-tone micropatterning from a single formulation. Mechanistic analyses, combining spectroscopic and physicochemical characterizations, reveal that the dual-tone response arises from the interplay between polymer chain scission and secondary photochemical reactions. Preliminary cytotoxicity assessments indicate favorable cytocompatibility, suggesting that PCLU photoresists could serve as a versatile platform for the development of more sustainable microfabrication in electronics, photonics, and biomedical applications.