Processible polyazomethines and polyketanils: From aerospace to light-emitting diodes and other advanced applications

Morphology control methods of aromatic polymers in concert with polymerization reaction are described in this review. Many attractive methods have been developed including reaction-induced phase separation of oligomers, epitaxial polymerization, shear-induced chain orientation during gelation, template-based polymerization, suspension polycondensation, solid-state polycondensation and liquid-liquid interfacial precipitation and so on. Among them, the reaction-induced phase separation of oligomers, in which there are two modes of crystallization and liquid-liquid phase separation, possess practically high potentiality to create novel polymer materials since it can control not only the morphology but also the molecular chain orientation. Ultimate goal is the embodiment of the nature system in a flask, that is, the control of the materials from primary structures to super structures. The morphology control methods by using polymerization reaction afford the valuable methodology for the three-dimensional structure architecture.

/pdf/morphology-control-of-aromatic-polymers-in-concert-with-5dfx5zwvi2.pdf

Morphology Control of Aromatic Polymers in Concert with Polymerization

Two new mesogenic monomers, namely 3,3’-dimethoxy-4,4’-di(hydroxyhexoxy)-N-benzylidene-o-Tolidine (Ia) and 4,4’-di(6-hydroxyhexoxy)-N-benzylidene-o-Tolidine (IIa), were reacted with cadmium sulfide (CdS) via an in situ chemical precipitation method in ethanol to produce CdS nanocomposites. A series of different mass compositions of CdS with Ia and IIa ranging from 0.1:1.0 to 1.0:1.0 (w/w) were prepared and characterized using X-ray Diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Polarizing Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC), X-ray Photoelectron Spectroscopy (XPS) and Photoluminescence Spectroscopy (PL). XRD showed that the broad peaks are ascribed to the formation of cubic CdS nanoparticles in both Ia and IIa. The average particle size for both nanocomposites was less than 5 nm with a narrower size distribution when compared with pure CdS nanoparticles. The analyses from POM and DSC demonstrated that mass composition from 0.1:1.0 up to 0.5:1.0 of CdS:Ia nanocomposites showed their enantiotropic nematic phase. On the other hand, polarizing optical microscopy (POM) for IIa nanocomposites showed that the liquid crystal property vanished completely when the mass composition was at 0.2:1.0. PL emissions for CdS: Ia or IIa nanocomposites indicated deep trap defects occurred in these both samples. The PL results revealed that addition of CdS to Ia monomers suppressed the photoluminescence intensity of Ia. However, the introduction of CdS to IIa monomers increased the photoluminescence and was at a maximum when the mass composition was 0.3:1.0, then decreased in intensity as more CdS was added. The XPS results also showed that the stoichiometric ratios of S/Cd were close to 1.0:1.0 for both types of nanocomposites for a mass composition of 1.0:1.0 (CdS:matrix).

/pdf/thermal-and-optical-properties-of-cds-nanoparticles-in-1i21qp4b9f.pdf

Thermal and Optical Properties of CdS Nanoparticles in Thermotropic Liquid Crystal Monomers

A new interesting class of linear Schiff-base poly(sulfone-ester)s has been synthesized by polycondensation of (E)-1-(4,4′-(4-hydroxy-3-chlorobenzylidene)thiocarbamoylaminophenyl-sulfonylphenyl)-3-(4-hydroxy-3-chlorobenzylidene)thiourea with 2,6-pyridinedicarbonyl chloride/thiophene-2,5-dicarbonyl dichloride. The enhancement of physical properties (thermal stability, glass transition temperature, mechanical strength, molar mass, electrical conductivity, etc.) of polymeric materials while maintaining their processability was the foremost aspiration of this research work. The pyridine or thiophene-based heteroaromatic poly(sulfone-ester)s (PSEs) showed ample solubility in amide solvents and good yield. PSEs possessed high inherent viscosity of 1.79–1.93 dL/g and molar mass 125 × 103–145 × 103 g mol−1. The polymers were thermally stable with 10 % weight loss in the range 538–547 °C and glass transition temperature between 293 and 296 °C. Further aim was to obtain novel miscible nano-blends exhibiting good electrical conductivity and heat stability. For this purpose, PAN doped with dodecylbenzenesulfonic acid (PAN/DBSA) was prepared by in situ doping polymerization, and then blended in solution/melt with PSEs. The resulting high performance materials potentially combined the fine thermal properties and processability of poly(sulfone-ester)s with electrical characteristics of polyaniline. FESEM of melt-blended PSEs/PAN/DBSA showed nano-level homogeneity of the microstructure liable for better electrical conductivity (2.7–3.2 S cm−1). The azomethine and pyridine moieties introduced in the backbone render these polymers thermally and mechanically stable as well as electrically conducting. The miscible blends, exhibited good heat stability (T
 10 520–527 °C, T
 g
 281–285 °C) and mechanical strength (55.20–57.18 MPa) compared with reported azomethine/polyaniline-based structures. New processable and high-performance engineering plastics, attractive for aerospace applications, can be fabricated using novel blends.

Processing and properties of new heteroaromatic Schiff-base poly(sulfone-ester)s and their blends

Morphosynthesis of nanostructured polyazomethines and carbon through constitutional dynamic chemistry controlled reaction induced crystallization process

Kohtaro Shirabe

Papers

Preparation of needle-like poly(azomethine) crystals by means of reaction-induced crystallization of oligomers