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Lyotropic mesomorphism of AB block copolymers in nematic solvents
Author(s) -
Schneider Armin,
Müller Stefan,
Finkelmann Heino
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(20000201)201:2<184::aid-macp184>3.0.co;2-a
Subject(s) - liquid crystal , micelle , copolymer , lyotropic , materials science , mesogen , small angle x ray scattering , phase (matter) , aqueous solution , solvent , crystallography , polymer chemistry , chemical engineering , chemistry , scattering , organic chemistry , polymer , optics , liquid crystalline , composite material , physics , optoelectronics , engineering
An AB block copolymer consisting of a liquid crystalline block A and an isotropic block B has been selectively dissolved in a low molecular weight nematic solvent (LMWNS). We investigated mixtures with fixed weight fractions using polarizing optical microscopy, small angle X‐ray scattering (SAXS), small angle neutron scattering (SANS) and 2 H NMR spectroscopy. The information obtained from the different methods that are selectively for the mesogen or micellar ordering (or for both) enables us to present the complete phase diagram. The A block of the copolymer is miscible in the nematic solvent and thus is termed “nematophilic” while the other constituent block is “nematophobic”. We show that these block copolymers in a nematic solvent behave like polymeric surfactants in aqueous solution. Here, the concept of amphiphilicity can be extended to a non‐aqueous anisotropic system. Cylindrical micelles are formed in the diluted regime. At higher concentrations the micelles form nematic and hexagonal phases. Thus, this highly complex system contains two different anisotropies: The superstructures of the anisotropic micelles and the ordering of the mesogens within (or around) the micelles.