Utilizing the sensitization effect for direct laser writing in a novel photoresist based on the chitin monomer N-acetyl-D-glucosamine

TL;DR

This paper introduces a novel bio-based photoresist derived from chitin's monomer, N-acetyl-D-glucosamine, utilizing a dual photoinitiator system that enhances laser writing capabilities through a sensitization effect.

Contribution

It develops a new bio-sourced resist from an animal-derived monomer and demonstrates a dual photoinitiator system that improves direct laser writing efficiency.

Findings

The bio-based resist is successfully synthesized from N-acetyl-D-glucosamine.

Using two photoinitiators enhances polymerization via a sensitization effect.

The approach enables the use of photoinitiators with low two-photon absorption for laser writing.

Abstract

The great flexibility of direct laser writing arises from the possibility to fabricate precise three-dimensional structures on very small scales as well as the broad range of applicable materials. However, there is still a vast number of promising materials which are currently inaccessible requiring the continuous development of novel photoresists. Here, a new bio-sourced resist is reported which relies on the monomeric unit of chitin, N-acetyl-D-glucosamine, expanding the existing plant-based biopolymer resists by a bio-based monomer from the animal kingdom. In addition it is shown that combined use of two photoinitiators is advantageous over the use of a single one. In our approach, the first photoinitator is a good two-photon absorber at the applied wavelength, while the second photoinitiator exhibits poor two-photon absorbtion abilities, but is better suited for crosslinking of the monomer. The first photoinitiator absorbs the light acting as a sensitizer and transfers the energy to the second initiator, which subsequently forms a radical and initializes the polymerization. This sensitization effect enables a new route to utilize reactive photointiators with a small two-photon absorption cross-section for direct laser writing without changing their chemical structure.