Supramolecular Thermotropic Liquid Crystalline Materials with Nematic Mesophase Based on Methylated Hyperbranched Polyethylenimine and Mesogenic Carboxylic Acid a Yu Chen, 1,2 Zhong Shen, 2 Lionel Gehringer, 2 Holger Frey,* 2 Salah-Eddine Stiriba* 3 1 Department of Chemistry, Tianjin University, 300072 Tianjin, P.R. China 2 Institut fu ¨r Organische Chemie, Johannes Gutenberg-Universita ¨t, Duesbergweg 10-14, 55099 Mainz, Germany Fax: (þ49) 6131 3924078; E-mail: hfrey@mail.uni-mainz.de 3 Instituto de Ciencia Molecular (ICMOL), Universidad de Valencia, Vicent Andre ´s Estelle ´s s/n, Burjassot, 46100 Valencia, Spain Fax: (þ34) 96 3543949; E-mail: salah.stiriba@uv.es Received: September 7, 2005; Revised: October 31, 2005; Accepted: November 2, 2005; DOI: 10.1002/marc.200500628 Keywords: dendrimers; hyperbranched; mesogen carboxylic acid; nematic phase; polyethylenimine; SAXS; self-assembly; supramolecular liquid crystal Introduction The construction of supramolecular liquid crystalline (LC) materials from polymeric backbones by self-assembly is a topic of great interest in supramolecular chemistry. [1] This is due to the intriguing properties displayed by these Summary: Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen- based carboxylic acid, 5-( p-cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phases were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X-ray diffractometry. Schematic illustration of the supramolecular assembly of CBPA with PEIMe backbone. Macromol. Rapid Commun. 2006, 27, 69–75 ß 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Communication DOI: 10.1002/marc.200500628 69 a : Supporting information for this article is available at the bottom of the article’s abstract page, which can be accessed from the journal’s homepage at http://www.mrc-journal.de, or from the author.