Synthesis and characterization of thermally stable aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles containing pendant substituted bezamides

Abstract

BackgroundThe introduction of pendent bulky groups along the polymer backbone results in a less ordered polymer matrix and increases the solubility characteristics without affecting thermal properties. The inclusion of chromogenic chemical moieties in the chains can give rise to the luminescent converter material which permits the preparation of materials with potential applications. Aromatic polymers containing heterocyclic rings in the main chain are known for their high thermal resistance, good hydrolytic stability, low dielectric and tough mechanical properties. There is currently much research directed towards the discovery of new blue light-emitting polymers, with characteristics of high efficiency and high reliability. Herein, we describe the preparation of aromatic polyamides and poly (1,3,4-oxadiazole-amide)s nanoparticles with pendant structures comprised of m- and p-acetoxybenzamide groups, where the acetoxybenzamide groups act as signaling units due to their fluorescent and chromogenic characteristics.ResultsAromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles with pendant structures comprised of m- and p-acetoxybenzamide groups were successfully prepared and characterized using different analytical methods. Most polyamides were obtained as well-separated spherical nanoparticles while aramide containing pyridine produced aggregated particles attributed to the molecular self assembly via H-bond directed organization of molecular precursors. The thermal behavior of all polymers exhibited two major thermal decompositions due to the subsequent breakage of the acetoxy group in the lateral chain and cleavage of the main amide bonds. Photoluminescence studies revealed that the blue emissions for the polyamide derived from benzidine were blue-shifted (shifted to a lower wavelength) compared to that of polyamides containing flexible linkages.ConclusionsWe report the synthesis of aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles with pendant structures comprised of m- and p-acetoxybenzamide groups. The thermal behavior of all polymers exhibited two major decompositions due to breakage of the acetoxy group in the lateral chain and cleavage of the main amide bonds. Structure- photoluminescence correlation demonstrated an interesting connection between structural modification and optical properties. The blue emissions for the polyamide derived from benzidine, attributed to the highly conjugation system, was blue shifted with the introduction of flexible linkages. The prepared polymers dissolved in warm polar aprotic solvents. Further investigations to obtain films with reasonably good mechanical properties for different applications are in progress.

Stable and ordered amide frameworks synthesised under reversible conditions which facilitate error checking

“…Amide bonds are highly stable and are considered practically irreversible under typical ambient conditions (rate constant for hydrolysis of amides 7 are of the order of 10 −11 s −1 ), including in acidic or basic aqueous solutions 8 , and are thermally robust 9 . Furthermore, amides are formed from cheap highly abundant components which display extensive structural and chemical diversity.…”

Stabilization of Tetrachloride with Mn (II) and Co (II)Complexes and 4-Tert-Butylpyridinium Organic Cation: Elaboration of the Structure and Hirshfeld Surface, Optical, Spectroscopic and Thermal Analyses

“…It can be seen that most of the organic cations do not give rise to bands in the visible domain [59][60][61][62]. The LMCT phenomenon (ligand-to-metal charge transfer) between the chloride atom Cl and metal atom Co can be observed in two bands located at 423 and 469 nm [63][64][65][66][67][68][69]. The bands located at 542, 558 and 576 nm are intended for d-d electronic transitions, showing that the geometry of the cobalt atom contain stetrahedral [CoCl 4 ] 2− ( 4 A 2 (F)→ 4 T 2 (F), 4 A 2 (F)→ 4 T 1 (F) and 4 A 2 (F)→ 4 T 1 (P), which are generally attributed to compounds based on cobalt Co (II) [70][71][72].…”

Investigation of the thermal ageing process and mechanism of benzoxazine/bismaleimide/cyanate ester copolymer

“…It is experimentally proved and generally accepted that the materials with high LOI values possess the superior flame retardant property. 32 LOI ¼ 17:…”