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Synthesis and characterization of liquid crystalline (norbornene‐ block ‐acetylene) block copolymers
Author(s) -
Koltzenburg Sebastian,
Ungerank Markus,
Stelzer Franz,
Nuyken Oskar
Publication year - 1999
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(19990401)200:4<814::aid-macp814>3.0.co;2-2
Subject(s) - copolymer , norbornene , thermotropic crystal , polymer chemistry , mesogen , materials science , differential scanning calorimetry , polymer , polymerization , liquid crystal , monomer , side chain , liquid crystalline , physics , optoelectronics , composite material , thermodynamics
We report the synthesis and characterization of block copolymers of mesogenic acetylene and norbornene moieties. As monomers, a norbornene derivative with cyanostilbenyl side groups and an acetylene derivative with a cholesteryl group were used. The almost quantitative polymerization is initiated with the well‐defined Schrock‐type molybdenum carbene Mo(CH‐ t ‐Bu)(NAr)(O‐ t ‐Bu) 2 with NAr = 2,6‐diisopropylaniline, t ‐Bu = tert ‐butyl. Polydispersity indices (PDIs) in the range of 2 for the block copolymers are obtained. The thermal and morphological behaviour of the polymers is characterized by means of differential scanning calorimetry (DSC) and X‐ray diffraction. Both homo‐ and copolymers form thermotropic mesophases, the acetylene polymer exhibiting a smectic A phase, while the polynorbornene is nematic. The block copolymer shows microphase separation retaining the homopolymers' mesophases. To our knowledge, the materials presented here are the first example of phase‐separated block copolymers of two side chain liquid crystalline polymers.