A new photoimaging system based on a trisdiazonium salt as a photocrosslinker for sulfonated polyelectrolytes

• Published in: European polymer journal 2009-06, Vol.45 (6), p.1785-1790
• Main Authors: Lomba, Miguel, Oriol, Luis, Sánchez, Carlos
• Format: Article
• Language: English
• Subjects: Applied sciences; Crosslinking and degradation; Diazo; Exact sciences and technology; Photocrosslinking; Photolithography; Physicochemistry of polymers; Polyelectrolyte complex; Polymers and radiations
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2009.02.018

A photocrosslinker based on a trisdiazonium salt has been synthesized from 4,4′,4″-triaminotriphenylamine. Polyelectrolyte complexes can be obtained by mixing the trisdiazonium crosslinker with poly(styrenesulfonate) (PSS). The polyelectrolyte complex precipitates when PSS is added in an ionic ratio of around 1:1 to a trisdiazonium salt solution. However, the addition of an excess of PSS to the mixture leads to redissolution of the precipitate. A mixture of PSS and the photocrosslinker (27 wt.%) can be processed from solution to give thin films by spin coating. When the films are irradiated with UV light, a change in the solubility of the material is observed, which is due to the decomposition of diazonium groups and the transformation of the ionic bond into a covalent one, which in turn transforms the polyelectrolyte complex into a covalent network. The process has been characterized by UV and IR spectroscopy. Photoimaging experiments have been performed on this material and polymeric relief structures have been obtained through a photolithographic process.