Influence of Hydroxy Functionalization and Metal Cross-Linking on Fiber Properties of Liquid-Crystalline Polyazomethines

Abstract

A number of semiflexible liquid-crystalline polyazomethines have been synthesized by condensation of two dialdehyde monomers (1,10-bis[(4-formyl-3-hydroxyphenyl)oxy]decane or 1,10-bis[(4-formylphenyl)oxy]decane) with two diamines (2-methyl-1,4-phenylenediamine or 3,3‘-dimethoxybenzidine). Polyazomethines having a hydroxyl group at the ortho position of the imine bond have higher degrees of polymerization and a remarkable tendency to show an increase in their molecular weight upon postpolymerization thermal treatments. These hydroxy-functionalized polymers have been coordinated with copper(II) ions to give rise to metallomesogenic cross-linked polymers. Fiber spinning of both organic and copper(II)-complexed polymers has been carried out, and the structure, orientation, and morphology of the fibers have been studied by X-ray diffraction, electron paramagnetic resonance, and scanning electron microscopy. The mechanical properties have also been evaluated. Hydroxy functionalization and copper(II) complexation are the key strategies to obtain highly oriented fibers with good mechanical properties and strong intermolecular cohesive forces. A highly oriented crystalline phase with improved mechanical properties could be developed by thermal annealing of “as-spun fibers”.

A silicon-containing polyazomethine and derived metal complexes: synthesis, characterization, and evaluation of the properties

“…Similar observations were reported in the literature. [46][47][48][49] For example, a glass transition domain centered at 39°C was observed for polyazomethine derived from 2,5-bis(n-dodecyloxy)terephthaldehyde and para-phenylene diamine. [46] The Cu and Co polymeric complexes exhibited similar T g values of 65.00 and 67.51°C, higher than the T g value of the starting polymer.…”

Synthesis and Characterization of New Polyamides with Substitutions in the Pendent Benzylidene Rings

“…When the azomethine groups are incorporated in to the polymer backbone, they exhibit good properties such as thermal stability [3,4], conductivity [5], fiber-forming ability [6,7], liquid crystalline behavior [8,9] and non-linear optical properties [10]. A drawback of the linear, aromatic rod-like poly(azomethine)s is their limited solubility in organic solvents.…”

Synthesis, characterization, and acoustic properties of new soluble polyurethanes based on 2,2′‐[1,4‐phenylenebis(nitrilomethylylidene)diphenol and 2,2′‐[4,4′‐methylene‐di‐2‐methylphenylene‐1,1′‐bis(nitrilomethylylidene)]diphenol

“…These moieties can act as hard segments of the PU chains. Schiff base polymers continue to be interesting materials because of their outstanding film-and fiber-forming properties, 2 semiconductor applications, 3,4 nonlinear optics, [5][6][7] and liquid-crystalline properties, [8][9][10][11][12] in addition to their thermal stability. 13,14 A variety of different types of Schiff base polymers have been synthesized and characterized with spectroscopic techniques.…”