Photo-induced crosslinking and thermal de-crosslinking in polynorbornenes bearing pendant anthracene groups

• Published in: European polymer journal Vol. 52; pp. 98 - 104
• Main Authors: Radl, Simone Viola, Roth, Meinhart, Gassner, Martina, Wolfberger, Archim, Lang, Andreas, Hirschmann, Benjamin, Trimmel, Gregor, Kern, Wolfgang, Griesser, Thomas
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2014; Elsevier
• Subjects: Anthracene; Applied sciences; Exact sciences and technology; Organic polymers; Photochemistry; Photolithography; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Ring opening metathesis polymerization; Anthracene; Photolithography; Ring opening metathesis polymerization; Photochemistry; Ring opening polymerization; Photochemical crosslinking; Norbornene derivative copolymer; Complex catalyst polymerization; Experimental study; Negative resist; Complex catalyst copolymerization; Anthracene derivatives; Functional polymer; Metathesis polymerization; Preparation; Diester; Unsaturated copolymer; Light sensitive copolymer; Norbornene derivative polymer; Unsaturated polymer; Chemical reactivity; Ring opening copolymerization; Photoresist
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2013.10.024

[Display omitted] •Polynorbornenes bearing anthracene groups were synthesized by ROMP.•The anthracene groups undergo a reversible cycloaddition upon UV-irradiation.•The photoreaction has been studied by UV–Vis spectroscopy.•This photodimerization reaction also leads to a crosslinking of the macromolecules.•The reversibility depends on the mobility of the anthracene groups in the polymer. Functional polynorbornenes bearing anthracene molecules in their side chain were synthesized by ring opening methathesis polymerization (ROMP). The pendant anthracene molecules undergo a [4π+4π] cycloaddition upon irradiation with UV-light, which was studied by means of UV–Vis spectroscopy in thin films of these polymers. This photodimerization reaction also leads to a crosslinking of the macromolecules due to the photodimer formation, resulting in a decrease in solubility of the UV illuminated areas. A thermally induced de-crosslinking could be obtained, revealing the reversibility of this photoreaction. The influence of the flexibility of the macromolecules, i.e. the mobility of the anthracene groups in the polymeric material, on the conversion rate, reversibility and the crosslinking behavior was studied by means of spectroscopy and sol–gel analysis. Furthermore, photo-patterned films were obtained by structured illumination and subsequent development with dichloromethane revealing a negative resist behavior.