M. Marcos, R. Alcalá, J. Barberá
Jul 29, 2008
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Journal
Chemistry of Materials
Abstract
The synthesis and characterization of ionic liquid crystal dendrimers and hyperbranched polymers based on the ammonium salts of commercially available dendrimers poly(propylene imine) [PPI-(NH2) n ] (with n = 16), and poly(amidoamine) [PAMAM-(NH2) n ] (with n = 16), and random hyperbranched poly(ethyleneimine) (PEI) and the prepared fully methylated PEI (namely PEIMe) with 5-(4-cyanophenylazophenyloxy)pentanoic acid (CAzPA) are reported. The occurrence of proton transfer from the carboxylic acid to the amine groups was confirmed by IR and NMR measurements. 5-(4-Cyanophenylazophenyloxy)pentanoic acid does not show mesogenic properties. However, all synthesized ionic complexes displayed a nematic mesophase. The liquid crystalline behavior was investigated by means of differential scanning calorimetry, polarizing light optical microscopy, and X-ray diffractometry. Themogravimetry analysis was carried out in order to determine the stability of the complexes, all of which have their mesophase−isotropic liquid ...