In situ thermal synthesis of novel polyimide nanocomposite films containing organo-modified layered double hydroxide: morphological, thermal and mechanical properties

Abstract

An organic-inorganic hybrid compound constituted by a Zn/Al layered double hydroxide (LDH) intercalated with citric acid (LDH-CA), was dispersed in polyimides (PIs) with N-benzonitrile side group, through in situ polymerization. At first, 3-(bis(4-aminophenyl)amino)benzonitrile as a diamine monomer was synthesis and then it was reacted with 4,4′-benzophenone tetracarboxylicdianhydride via thermal imidization method to formed prossable PI. To improve the thermal and mechanical properties and also to avoid the aggregation of LDH particle in the polymer matrix, small amount of LDH-CA (1, 2, 4 wt %) was added to the synthesized PI. The resulted materials were characterized by Fourier transform-infrared spectroscopy, X-ray powder diffraction, thermogravimetry analysis (TGA), field emission-scanning electron microscopy, and transmission electron microscopy (TEM) techniques. TEM results showed that the LDH-CA nanolayers were dispersed in PI matrixes. The mechanical and thermal properties of the synthesized composites are effectively enhanced by the incorporation of 2wt.% LDH-CA in the polymer matrix. For the PI/LDH-CA nanocomposites, the maximum degree of tensile strength is observed at a LDH-CA loading of 2 wt%, corresponding to an almost 32% increase in tensile strength compared to the pure PI. IntroductionOrganic/inorganic hybrid materials have attracted widespread consideration owing to their potential uses as flame retardant materials, gene and drug delivery and catalyst carriers. 1 Polymeric nanocomposites (NCs) are a new class of materials consisting of nanosized fillers in a polymeric matrix, and possess properties superior to those of conventional microsized filler composites, due to the ultrafine dimensions of the filler. 2,3 Moreover, on account of the unique properties such as enhanced mechanical and thermal properties, reduced flammability as well as high chemical stability, polymer/layered crystal NCs have been recognized as one of the most important organic/inorganic hybrid materials. 4-6 Most of the published works has focused on organically modified smectite clays, in particular montmorillonites, as fillers of polymeric composites. 7-9 Furthermore, the emphasis is placed on layered double hydroxide (LDH) systems rather than clays in recent years due to artificially preparing and highly tunable properties. 10,11 LDHs are a kind of anion clay with unique properties that are not commonly observed in layered silicates. LDHs are well characterized and conventionally used for flame retardants, 12 catalysts, 13 ion exchangers, 14 matrices for biosensors, 15 and supercapacitor electrode material. 16 Their novelty originate from their broad range of chemical composition, highly tunable properties, ease of synthetic procedures in the laboratory, stability in air, interchangeable anions and their potential industrial uses. 17 Ultrathin nanosheets, prepared by delamination of layered hydroxides, have attracted attention due to the extremely small thickness of the order of 1 nm and large lateral size of the order...

Enantioselective Copper(I/II)‐Catalyzed Conjugate Addition of Nitro Esters to β,γ‐Unsaturated α‐Ketoesters

“…The incorporated anions and water between the layers and various metal cations (M 2+ / 3+ ) results in a larger interlayer space and unique redox characteristics in LDHs, respectively, providing a notable electrochemical performance 20–22. Recent studies have been shown that LDHs are electrocatalytically active and offer superb a high stability for long‐term employment 23–25.…”

Structural, thermal and mechanical properties of polymer nanocomposites based on organosoluble polyimide with naphthyl pendent group and layered double hydroxide

“…In the spectra of the PI, absorption bands of the imide groups appeared at 1774 and 1718 cm −1 for the antisymmetric and symmetric stretching vibrations of the carbonyl groups. 41 The bands around 1374 and 816 cm −1 were ascribed to the stretching and bending vibrations of C–N–C in the imide ring (Figure 2(b)).…”

Effect of sepiolite nanoparticles on the properties of novel poly(sulfone ether imide)

“…Therefore, synthesis of PIs containing such functional groups along their main chains or within their side chains is the most frequently used method to tailor their properties. Moreover, introduction of nanoparticles and preparation of related nanocomposites would further improve their properties . As it has been widely proved, the presence of some types of nanoparticle or nanofiber in PI and PI copolymer matrices results in improved thermo‐mechanical and physical properties of polymers without deteriorating their desirable intrinsic features …”

“…Moreover, introduction of nanoparticles and preparation of related nanocomposites would further improve their properties. [11][12][13] As it has been widely proved, the presence of some types of nanoparticle or nanofiber in PI and PI copolymer matrices results in improved thermo-mechanical and physical properties of polymers without deteriorating their desirable intrinsic features. [14][15][16] Sepiolite (Sep) is a hydrated magnesium silicate having the half-unit cell chemical formula of Mg 8 Si 12 O 30 (OH) 4 .12H 2 O.…”