Design of Side Chain and Main Chain Liquid Crystalline Polymers Containing Supramolecular Quasi-Rigid-Rodlike Mesogens Obtained from Collapsed Main Chain Macrocyclics

Abstract

The synthesis of the AB2 mesogenic group 13-hydroxy-1-(4-hydroxyphenyl)-2-(4-hydroxy-4‘-biphenylyl)tridecane (TPT‘-OH, 11) and its use in the preparation of 1,12,33,44-tetraoxa-25-[(methacryloyloxy)undecanyl]-57-ethyl[12.0.2.12.0.2]paracyclophane (17), 1,12,33,44,65,76-hexaoxa-25-[(methacryoyloxy)undecanyl]-57,89-diethyl[12.0.2.12.0.2.12.0.2]paracyclophane (24), and 1,12,33,44,65,76,97,108-octaoxa-25-[(methacryloyloxy)undecanyl]-57,89,121-triethyl[12.0.2.12.0.2.12.0.2.12.0.2]paracyclophane (30) and of the corresponding polymethacrylates 18, 25, and 31 are described. Monomers 17, 24, and 30 are the main chain cyclic dimer, trimer, and tetramer, respectively, of 1-(4-hydroxyphenyl)-2-(4-hydroxy-4‘-biphenylyl)butane (TPB‘, 13) with 11 and 1,10-dibromodecane and, therefore, are attached to the methacryloyl group through a spacer containing 11 methylenic units. The collapsed conformation of these macrocyclics combined with their degree of oligomerization places these quasi-rigid-rodlike mesogens side-on in 18, end-on in 25, and in between side-on and end-on in 31. The synthesis of the biselectrophilic macrocyclic main chain dimers 1,7,28,34-tetraoxa-20,47-bis(bromohexyl)[7.0.2.7.0.2]paracyclophane (40) from 8-hydroxy-1-(4-hydroxyphenyl)-2-(4-hydroxy-4‘-biphenylyl)octane (TPO-OH, 36) and 1,5-dibromopentane and 1,12,39,50-tetraoxa-32,70-bis(bromoundecanyl)[12.0.0.2.12.0.0.2]paracyclophane (46) from 13-hydroxy-1-(4-hydroxyphenyl)-2-(4-hydroxy-4‘‘-terphenylyl)tridecane (TPT-OH, 42) and 1,10-dibromodecane is also presented. Their phase transfer-catalyzed polyetherification with TPB‘ produced the main chain polyethers 41 and 47. The mesomorphic behavior of these first examples of side chain and main chain polymers containing macrocyclic mesogens is discussed. In spite of the long spacer used in the design of these polymers, they do not crystallize and also do not display smectic phases. 25, 31, and 47 exhibit an enantiotropic nematic phase, while 18 and 41 are amorphous. The use of the spacer in the construction of both the macrocyclic mesogen and the corresponding main chain and side chain liquid crystalline polymers provides the highest degree of conformational disorder from all known polymers exhibiting a nematic mesophase.