Thermal Structuring of Surface‐Attached Polymer Networks by C,H Insertion Reactions

• Published in: Macromolecular materials and engineering Vol. 307; no. 11
• Main Authors: Bleiziffer, Alexander, Kost, Jonas, Rühe, Jürgen
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.11.2022
• Subjects: Control surfaces; Copolymers; Crosslinking; C–H insertion; diazo compounds; Insertion; Material properties; percolation; Photolithography; Polymer films; polymer networks; Polymers; Substrates; surface modification; thermal crosslinking; thermal patterning; thermal structuring
• ISSN: 1438-7492; 1439-2054
• DOI: 10.1002/mame.202200345

Photolithography is an important process in semiconductor technology with the aim to create structured surfaces, but often requires specific substrate materials that have to be pretreated. Using a novel, fast, and simple process based on thermal activation, the authors are able to produce spatially controlled surface‐bound polymer networks on a variety of different common materials. In this process, which is similar to branding livestock or wood with a hot branding iron, a hot stamp is brought into direct contact with a diazo group‐containing copolymer applied to a substrate to map the profile of the stamp into the polymer film. Crosslinking and covalent surface attachment to the substrate are achieved as a result of thermal activation of the diazo groups, leading to carbene formation, which induces C,H‐insertion crosslinking (CHic). After dissolving the uncrosslinked material, the shape of the stamp is transferred into the polymer film. The polymer systems used here allow activation of the diazo function at mild temperatures, so that relatively fast processing allows the performance of step‐and‐repeat processes. By recoating and then repeating the process on already structured surfaces, the physical and chemical material properties of structures can be tailored, and structure‐on‐structure features become easily possible. Through local thermal activation, diazo group‐containing polymer films can be crosslinked selectively   and simultaneously attached to a variety of materials by C,H insertion reactions, generating thermally patterned surfaces. The generation of various geometries, microstructures, and the adjustment of the physical and chemical surface properties by step‐and‐repeat processes are described.