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Exploring ultrafast igniting and hydrolytically stable ionic liquids (ILs) has a wide scope in hypergolic rocket fuels. The hydrophobicities of ILs, induced by a smart change in alkyl substituents of imidazolium cations with energy-rich cyanoborohydride, [BH3CN]− and dicyanamide, [DCA]− anions were examined for the first time. The physico-chemical properties and performance of ILs were also studied. Consequently, hydrolytic stability in terms of moisture study of all the ILs was thoroughly investigated under standard environmental conditions. The analysis indicates that the IL 14, 1-allyl-3-octyl imidazolium cyanoborohydride is most hydrophobic and hydrolytically stable. Studies evaluating the role of the cationic hydrocarbon chain and the nature of anions of ILs on the properties of hypergolic fuel were carried out. All the ILs are liquid at room temperature and exhibit a positive heat of formation. IL 10, 1,3-diallyl-imidazolium cyanoborohydride exhibited the shortest ignition delay of 1.9 ms with WFNA and IL 11, 1-allyl-3-ethyl imidazolium cyanoborohydride presented the lowest viscosity of 16.62 mPa s. Therefore, these ILs can be suggested as potential candidates for replacing acutely toxic and carcinogenic hydrazine and its methylated derivatives as hypergolic fuels. [ABSTRACT FROM AUTHOR]

In the present work, hyperbranched polyurethanes were prepared by using oligomeric A 2 + B 3 approach. The synthesis of hyperbranched polymers was carried out by reaction of trimethylolpropane (TMP) with poly(ethylene glycol) (PEG) terminated isophorone diisocyanate (IPDI). The prepared hyperbranched polymers were confirmed by Fourier transform infrared spectroscopy (FTIR) and 1 H nuclear magnetic resonance ( 1 H NMR). The crystallization properties studied with X-ray diffraction (XRD) and polarized optical microscopy (POM) indicated that hyperbranched polymers had crystalline structure and degree of crystallization reduces with introduction of hard segment. The maximum latent heat of fusion was found to be 145 J g −1 at 55 °C. Field emission scanning electron microscopy (FESEM) showed presence of homogeneous structure and thermogravimetric analysis (TGA) results indicated that the materials have good thermal stability. Thermal reliability tests from 20 thermal cycles demonstrate that enthalpy of hyperbranched polyurethanes improves with thermal cycling without any chemical degradation. These materials can be successfully used as polymeric phase change materials for thermal energy storage applications. [ABSTRACT FROM AUTHOR]

In this study, we report the synthesis of a Pb(II) ion-imprinted interpenetrating polymer network (II-IPN) by simultaneous polymerization for selective extraction of Pb(II) from printed-circuit-board (PCB) recycling unit wastewater. Initially, a polymer network was synthesized by polymerization of methacrylic acid (monomer) and ethylene glycol dimethacrylate (cross-linker) and a second polymer network by chitosan (complexing monomer) and tetraethyl orthosilicate (cross-linker). The chemical structure and morphology of the II-IPN were analyzed using Fourier transform infrared, field-emission scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The interaction of the functionality in the II-IPN with Pb(II) through chelation was studied by X-ray photoelectron spectroscopy analysis. The maximum adsorption capacities for II-IPN and nonimprinted interpenetrating polymer network were 37.5 and 10.3 mg g-1, respectively. The largest selectivity coefficient for Pb(II) in the presence of W(VI) was 161.58. The developed Pb(II) II-IPN was successfully employed for selective extraction of Pb(II) from PCB recycling unit wastewater. [ABSTRACT FROM AUTHOR]