Synthesis, liquid-crystalline properties, and supramolecular nanostructures of dendronized poly(isocyanide)s and their precursors.
A series of novel dendronized pi-conjugated poly(isocyanide)s were synthesized successfully by using a Pd-Pt mu-ethynediyl dinuclear complex ([ClPt{P(C2H5)3}2C[triple bond]CPt{P(C2H5)3}2Cl]) as the initiator. The polymerizations of the dendronized monomers follow first-order kinetics, indicating that living polymerization takes place. The obtained polymers exhibit narrow polydispersities in the range of 1.03-1.20. Thermal properties of the poly(isocyanide)s as well as their isocyanide monomers and precursors with formamido (HCONH-) moieties as apexes were investigated by using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). Both the peripheries and the apex groups of the dendrons affect the formation of supramolecular column and/or cubic phases of the precursors and monomers. The formamido precursor forms a liquid-crystalline phase due to intermolecular hydrogen bonding. The isocyanide monomer lacks this hydrogen-bonding ability and does not display an organized mesophase. All of the rigid poly(isocyanide)s with the monodendrons exhibit columnar liquid-crystalline phases. Interestingly, cylindrical structures of a poly(isocyanide) were directly visualized by using transmission electron microscopy (TEM).
Tian
Yanqing
Y
Department of Applied Chemistry, Graduate School of Engineering, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397, Japan. yqtian@u.washington.edu
Kamata
Kaori
K
Yoshida
Hirohisa
H
Iyoda
Tomokazu
T