Novel poly(thiourea-ether-imide)s derived from 4,4′-oxydiphenyl-bis(thiourea): probing the possibility for high-temperature applications: Novel poly(thiourea-ether-imide)s

Nanocomposites of poly(thioureaamide) with carbon nanotube

In the current study, poly(thioureaamide) (PTA) was prepared from isophthaloyl diisothiocyanate and p-phenylenediamine using a facile condensation technique. Fourier transform infrared and proton nuclear magnetic resonance spectroscopic analyses confirmed the structure of the polymer obtained. PTA was then used as a matrix to synthesize organic hybrid materials. In this regard, the functionalized and nonfunctionalized multiwalled carbon nanotubes (CNTs) were utilized as fillers in this work to prepare the nanocomposites. In PTA and functional CNTs system, better compatibility between the organic matrix and the filler was confirmed using field effect scanning electron microscope. The micrographs revealed that the nanotubes were well dispersed in the matrix and packaging of polymer over the surface of functional CNTs. The interaction between polymer chains and functional reinforcement produced mechanical and heat-stable nanocomposites. The tensile strength of the functional CNT-based hybrids 53.21–57.11 MPa was improved as compared with the nonfunctional system (32.79 MPa). The 10% gravimetric loss (513–556°C) and the glass transition temperature of PTA/functional CNTs (184–191°C) depicted a considerable improvement over PTA/nonfunctional CNTs. The results showed the enhanced interactions between the two phases in PTA/functional CNT-based nanocomposites relative to PTA/nonfunctional CNTs.

Investigation of physical properties and structure–property relationship in new poly(azo-sulfone-amide)s

Series of aromatic polyamides containing azo groups have been synthesized by the phosphorylation polycondensation of a new dicarboxylic acid ( E)-1-(4-(4-(3-carboxypyridylazo)thiocarbamoylaminophenyl-sulfonyl)phenyl)-3-(3-carboxypyridylazo)-thiourea and various diamines. Poly(azo-sulfone-amide)s (PASAs) were characterized using spectroscopic techniques, solubility, molar mass, electrical conductivity, mechanical strength, nonflammability, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies. PASAs possessed fine solubility in polar solvents and high molar mass 70 × 103–75 × 103 gmol−1. These polyamides showed fibrous structure according to field-emission scanning electron microscopy (FESEM). Thermal and nonflammability data indicated that PASAs were fairly stable above 500°C having initial weight loss of around 525–531°C, 10% of gravimetric loss in the range of 542–563°C, own high glass transition temperature 257–267°C and limiting oxygen index (LOI) values (35–47%). The polymers also demonstrated higher tensile strength (61.10–74.29 MPa) and elongation at break (1.49–1.57). FESEM images displayed fibrous morphology of the PASAs. Moreover, polyamides showed superior electrical conductivity (1.45–1.92 S cm−1). Fine balance of the properties render the new PASAs potential engineering plastics for a number of aerospace relevance.

Nanoblends of novel polyesters with polyaniline: Conductivity and heat-stability studies

The present work initially deals with the fabrication of a new generation of polyesters (bearing thiophene, azomethine, thiourea and ether moieties) and subsequent blending with polyaniline (PAN) exhibiting extremely valuable nanoblend characteristics. Few poly(azomethine-thiourea-ester)s (PATEs), by the polycondensation of a new diol 4,4′-oxydiphenyl bis(( E)-1-(4-hydroxobenzylidene)thiourea) with thiophene-2,5-dicarbonyl/terephtaloyl chloride, were synthesized. The polymers obtained were characterized by Fourier-transform infrared, proton-nuclear magnetic resonance, solubility, solution viscosity, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle x-ray diffraction. The polymers exhibited high molar mass (77–89 × 103) and thermal stability ( T10 528–531°C, glass transition temperature ( Tg) 265–268°C). Then the electrically conducting blends, of PAN dispersed in the PATEs matrix, were prepared by mash-blending and melt-blending techniques. Materials obtained by conventional melt-blending approach generated an efficient conductive network compared with those produced by mash blending. Field emission scanning electron microscopy images displayed nanoblend morphology of the melt-blended system, owing to increased physical interactions (hydrogen bonding and π–π stacking) between the two polymers. Moreover, miscible blends of thiophene-based PATE/PAN led to superior conductivity (1.5–2.1 S/cm) and heat stability ( T10 503°C) even at low PAN concentration relative to previous thiophene, azomethine or PAN-based structures.

New heat resistant poly (thiourea-amide-imide)s derived from 1-(1,3-dioxo-2-(4-aminophenyl) isoindolin-5-yl)carbonyl-3-(4-aminophenyl) thiourea for high performance applications

Novel heat-resistant and organosoluble poly(thiourea-amide-imide)s (PTAIs) were synthesized through the condensation of trimellitic anhydride chloride (TMAC)-derived imide ring bearing diamine (1-(1,3-dioxo-2-(4-aminophenyl)isoindolin-5-yl)carbonyl-3-(4-aminophenyl) thiourea) with various diacid chlorides. Physical properties of PTAIs including crystallinity, organosolubility, thermal properties, flame retardancy, solution viscosity along with molecular weights were investigated. Accordingly, polymers bearing phenylthiourea moieties displayed an amorphous nature and were readily soluble in amide solvents having ηinh of 1.11–1.37 dL g−1. Moreover, gel permeation chromatography measurements revealed Mw around 76 869–80 391. Thermal stability of these polymers was ascertained via 10% weight loss temperatures around 517–544°C in an inert atmosphere. Furthermore, glass transition temperatures of PTAIs were found to be 286–292°C. Limiting oxygen index (LOI) measurements indicated that new copolymers were efficiently flame retardant as compared to several reported materials. Hence, incorporation of thiourea functionalities into the polymer backbone was demonstrated to be an effective way to enhance their thermal properties and flame retardancy.