Intramolecular Cyclization of Reactive Mesogens for Applications in Optical Films and Coatings
Zusammenfassung der Projektergebnisse
In this project we developed further understanding about the thermotropic and lyotropic liquid crystalline properties of diallylammonium salts and about their photopolymerization reaction. We compared the polymerization process of diallylamines with the polymerization of acrylic acid. The polymerization is simply carried out by the addition of a photoinitiator and a low power UVA domestic sunlamp. We observed that the speed of the polymerization of diallylammonium salts is comparable to acrylic acid. Already 10 mol% of an acid significantly improves the speed of the photopolymerization of the diallylamines. The NMR data support the formation of five membered rings and thus the mechanism Polymer of 16 and M6 retain salt like structure. Furthermore we presented the synthesis of the bifunctional monomer 19 with an acrylate and a diallylamine moiety. We could demonstrate by FT-IR and UV-DSC, that a stepwise polymerization of this monomer is possible. The photopolymerization of the bifunctional monomer 25 on the other hand is a comparably slow process. We improved the synthesis towards fluorinated terphenyls. The formation of thermotropic liquid crystals with fluorinated terphenyls and cyano biphenyls as core is strongly hindered by the introduction of a diallylamine moiety and even more so in the case of diallylammonium salts. For this reason further investigations about the thermotropic properties of such materials were stopped and we focused our work on the lyotropic properties. Monomers with a diallylammonium salt and a long alkyl chain can easily be synthesized. Such amphiphiles e.g. 28a and 28b form on the addition of water lyotropic phases. The material properties can be varied by the choice of bridging group and the type of counterion employed. We have successfully polymerized different lyotropic phases and were also able to make cross-linked polymer networks by addition of a bisdiallylammonium salt. Such materials might find very interesting applications in the development of membranes.
Projektbezogene Publikationen (Auswahl)
- Chem. Commun., 2010, 46, 6452–6454
N. A. Bongartz, J. W. Goodby
- Intramolecular Cyclisation of Reactive Mesogens for Applications in Optical Films and Coatings, British Liquid Crystal Society (BLCS) 2010 Conference, 29. – 31.03.2010, Lawns Centre, University of Hull, Cottingham
N. A. Bongartz, J. W. Goodby
