Supramolecular main-chain liquid crystalline polymers and networks with competitive hydrogen bonding

Abstract

A series of supramolecular polymers and networks with variable liquid crystalline characteristics have been created. These species are formed though the benzoic acid/pyridine associations of a flexible bisacid and a mixture of a rigid bispyridyl and a non-mesogenic tetrapyridyl. The networked systems displayed liquid crystalline characteristics up to and including 22.5% netpoint inclusion. Above this concentration, only crystalline and melting behaviours were observed. This observed phenomenon would seem to be linked to the statistical correlation of hydrogen bond acceptors and donors. There was also no observed phase segregation of the species after multiple heat/cool cycles and extended periods of time in the isotropic state. This would indicate that the thermodynamically more stable mesogenic phase cannot out-compete the non-liquid crystalline network. Computational analysis indicates no significant difference in hydrogen bond strength between the two different hydrogen bond acceptors.

Keywords:

• liquid crystals
• networks
• supramolecular
• hydrogen bond

Acknowledgements

The authors would like to thank the Petroleum Research Foundation (54134-B7), the National Science Foundation (Award Number 0804428) and The Office of Research and Sponsored Programs at the University of Wisconsin- Eau Claire for their financial support of this work. The authors would also like to personally thank David Schiraldi and Clinton J. Cook for their assistance in this endeavour.