Evaluation of physicochemical properties and catalytic activity of poly(PMDAH-co-ODA/PPDA) nanocomposites towards the removal of toxic pollutants

Synthesis of Polyimides (PIs) between pyromellitic dianhydride (PMDAH) and oxydianiline (ODA) or p-phenylenediamine (PPDA) in the presence and absence of V₂O₅ and Ag nanoparticles (NPs) were carried out under N₂ atmosphere at 160 °C for 5 h with vigorous stirring in N-methylpyrrolidone (NMP) solvent. The prepared PI and its nanocomposites were analyzed by FT-IR spectroscopy, ¹H NMR spectroscopy, FE-SEM, SEM, DSC and TGA like analytical instruments. The FE-SEM showed various surface morphologies for different PI nanocomposites. The particle size of the prepared nanoparticles was calculated as less than 60 nm for Ag and 15 nm for V₂O₅ nanoparticles by HR-TEM. The PI nanocomposites embedded with Ag nanoparticles (P2 and P5) showed a higher thermal stability than the pristine PIs (P1 and P4) and PI/V₂O₅ nanocomposites (P3 and P6). Further, the possible application of metal (Ag) and metal oxide (V₂O₅) NPs embedded PI nanocomposites was assessed on the catalytic reduction of highly toxic Cr(VI), Rhodamine 6G (R6G) dye and p-nitrophenol (NiP) pollutants with the help of a reducing agent (NaBH₄). The apparent rate constant (k_app) values were calculated to assess the catalytic efficiency of the prepared PI and its nanocomposites. The PI/Ag nanocomposite (P2) system showed an efficient catalytic reduction than the other systems.

One-pot synthesis of semicrystalline polyamide imide based on 4,4’-diaminobenzanilide and 2,2-propylidene-bis(1,4-phenyleneoxy)diphthalic anhydride in molten benzoic acid

High-temperature thermoplastic semicrystalline polyamide imide (PAI) with Tg = 250°C, and Tm = 370°C was synthesized from 4,4’-diaminobenzanilide, and 2,2-propylidene-bis (1,4-phenyleneoxy) diphthalic anhydride using three different methods: one-pot high-temperature catalytic polycondensation in molten benzoic acid (BA), low-temperature polycondensation (LTP) in dimethylacetamide (DMAA) followed by chemical imidization, and LTP followed by imidization. The influence of the synthetic route on the crystallinity of PAI was studied by wide-angle X-ray scattering. The PAI synthesized in molten BA comprised a reactive oligomer, which on heating up to 360°C easily transformed into high-molecular-weight PAI. The thermal and rheological properties of the high-molecular-weight PAI thus prepared were studied using differential scanning calorimetry, trimellitic acid, thermogravimetric analysis, and capillary viscosimetry. The rheological characteristics indicate that the obtained PAI can be melt processed by extrusion and hot pressing at 370–380°C.

Geomimetics and Extreme Biomimetics Inspired by Hydrothermal Systems-What Can We Learn from Nature for Materials Synthesis?

'Extreme biomimetics' and 'geomimetics' are relatively recent fields of materials chemistry. Both take inspiration from natural materials for generating novel synthetic materials or enhanced properties in known materials. In geomimetics, the source of inspiration is geological systems, while extreme biomimetics is motivated by organisms operating in-from an anthropocentric point of view-extreme conditions. This review article focuses on geomimetic and extreme biomimetic hydrothermal synthesis. Since hydrothermal preparative chemistry typically uses nothing but water and the required precursors, the field belongs to the research area of 'green materials chemistry'. Geomimetics, on the one hand, takes inspiration from natural materials formation. Extreme Biomimetics, on the other hand, is inspired by materials found in extremophile organisms, instead of aiming to implement their actual biosynthesis. In this contribution, both extreme biomimetics and geomimetics are first defined, and further critically discussed on the basis of recent, selected examples. Moreover, the necessity for the two closely related fields as well their prospects are commented on.