Comblike liquid-crystalline polymers from ionic complexation of dendronized polymers and lipids

This work describes the self-assembly behavior, the structure, the state, and phase diagrams of comblike liquid-crystalline polymers obtained by supramolecular ionic complexation of cationic dendronized polymers (PG1-PG3) and anionic sulfonated lipid surfactants. In order to characterize the influence of both the polymer and the surfactant on the microphase separation of these complexes, dendronized polymers with generation 1 <= n <= 3, carrying 2(n) positive charges per monomer, were complexed with a stoichiometric amount of anionic sodium alkyl monosulfate surfactants with hydrocarbon chain of C-8, C-12, C-14, and C-18 lengths. Supramolecular complexes were obtained in water, and the complexation process was monitored by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance. After drying and thermal annealing under high vacuum, the complexes showed thermotropic liquid-crystalline behavior as demonstrated by both cross-polarized optical microscopy and differential scanning calorimetry. Small-angle X-ray scattering allowed determining the respective lattice parameters and type of structures for all the complexes considered. Depending on both generation and lipid chain length, amorphous isotropic fluid, columnar rectangular, columnar hexagonal, columnar tetragonal, and lamellar phases were observed, each characterized by a specific order-disorder transition temperature (T-ODT).