Glycidate as a High-Strength Epoxy Adhesive Curable with Amine under Ambient Conditions

This paper reports that glycidates bearing epoxy moieties with adjacent ester can be cured with diethylenetriamine (DETA) under mild conditions and exhibit high adhesiveness. Curing of bifunctional glycidates with DETA gave cross-linked products. The curing started at a lower temperature (7 °C) than the analogous glycidyl ether (27 °C), while the rate of the curing was slower due to the lower activation energy (Ea = 57 kJ/g) and exothermicity (ΔH = 58 J/g) as confirmed by DSC analysis. The curing system of neopentyl glycol diglycidate and DETA effectively adhered aluminum plates by curing at 25 °C, and the strength was more than five times higher than the curing with analogous glycidyl ether. The higher adhesive strength under curing of ambient conditions and facile preparation of monomers are the significant advantages of this curing

Reversible Gelation System for Hydrazine Based on Polymer Absorbent

Reversible absorbents for safe storage of toxic hydrazine were developed. Various cross-linked polar polymers were examined as absorbents for hydrazine and its 35% aqueous solution, and structurally similar polymers were found to be suitable for effective absorption. Namely, cross-linked polyacrylamide (CPAM) was most effective among examined various hydrophilic polymers. CPAM absorbed 43- and 31-fold heavier amounts of absolute hydrazine and 35% aqueous solution, respectively, by simple soaking. Absorbed hydrazine could be quantitatively released either by N2 gas flow and compression, and the resulting absorbent reabsorbed hydrazine without loss of the absorption ability. The absorption ability was higher than conventional covalent storages, and the release protocol, without dissolution of the absorbent, are suitable for storage systems in hydrazine fuel cells

Thermo-Reversible Gelation of Aqueous Hydrazine for Safe Storage of Hydrazine

A reversible gelation–release system was developed for safe storage of toxic hydrazine solution based on gelation at lower critical solution temperature (LCST). Poly(N-isopropylacrylamide) (PNIPAM) and its copolymer could form gels of 35wt% hydrazine by dissolution under low temperature and storage at ambient temperatures. For example, PNIPAM gelled a 63 fold heavier amount of 35wt% hydrazine. Aqueous hydrazine was released from the gels by compression or heating, and the gelation–release cycles proceeded quantitatively (> 95%). The high gelation ability and recyclability are suitable for rechargeable systems for safe storage of hydrazine fuels

One-Pot Synthesis of Organic-Sulfur-Zinc Hybrid Materials via Polycondensation of a Zinc Salt and Thiols Generated in Situ from Cyclic Dithiocarbonates

Soluble organic-sulfur-zinc hybrid polymers were prepared via a one-pot reaction consisting of ring-opening addition and subsequent polycondensation. The first reaction is the nucleophilic ring-opening addition of 2-ethylhexylamine to multifunctional cyclic dithiocarbonates giving multiple thiols in situ. The sequential polycondensation of the in situ generated thiols with Zn(OAc)2 gave the target hybrid polymers. This one-pot method enabled the use of a shorter amine than the previous polycondensation of Zn(OAc)2 and purified thiols, which required octadecylamine to obtain a soluble product. The obtained hybrid polymers may be cast as composite films with polystyrene and poly(methyl methacrylate). Owing to the shorter alkyl chain, the calculated nD values of the products (1.60 or 1.61) are higher than that of the previous product bearing octadecyl chains (1.53)

Lemon Juice Assisted Green Synthesis of Reduced Graphene Oxide and Its Application for Adsorption of Methylene Blue

Sustainable synthesis of reduced graphene oxide (rGO) is of crucial significance within the development of carbon nanomaterials. In this study, a green and eco-friendly strategy for the synthesis of rGO using lemon juice as the reducing agent for graphene oxide (GO) without using toxic and harmful chemicals was demonstrated. The reduction with lemon juice effectively eliminated the oxygen-containing functionalities of GO and regenerated the conjugated systems as confirmed by the UV-vis and FTIR spectroscopic and X-ray diffraction analyses. Microscopic evaluation showed the successful manufacturing of exfoliated and separated few layers of nano-sheets of rGO. The application of the resultant rGO as an adsorbent for organic pollutants was investigated using methylene blue (MB) as a model. The adsorption kinetics of MB on rGO is best matched with the pseudo-second-ordered kinetic model and the Langmuir model with a high adsorption capacity of 132.2 mg/g. The rGO exhibited good reusability with a removal efficiency of 80.4% in the fourth cycle. This green method provides a new prospect for the large-scale production of rGO in a cost-effective and safe manner

Synthesis of Hydrophilic Sulfur-Containing Adsorbents for Noble Metals Having Thiocarbonyl Group Based on a Methacrylate Bearing Dithiocarbonate Moieties

Novel hydrophilic sulfur-containing adsorbents for noble metals were prepared by the radical terpolymerization of a methacrylate bearing dithiocarbonate moieties (DTCMMA), hydrophilic monomers, and a cross-linker. The resulting adsorbents efficiently and selectively adsorbed noble metals (Au, Ag, and Pd) from various multielement aqueous solutions at room temperature owing to the thiocarbonyl group having high affinity toward noble metals. The metal adsorption by the adsorbents was proceeded by simple mixing followed by filtration. The noble metal selectivity of the adsorbent obtained from DTCMMA and N-isopropylacrylamide was higher than that of the adsorbent obtained from DTCMMA and N,N-dimethylacrylamide due to the lower nonspecific adsorption

Preparation of TiO2-Poly(3-Chloro-2-Hydroxypropyl Methacrylate) Nanocomposite for Selective Adsorption and Degradation of Dyes

We report a new nanocomposite TiO2-poly(3-chloro-2-hydroxypropyl methacrylate) (TiO2-PCHPMA) for selective adsorption/degradation of cationic dyes and degradation of anionic dyes. TiO2-PCHPMA was prepared by free radical polymerization of CHPMA in the presence of TiO2 modified with 3-(trimethoxysilyl)propyl methacrylate. TiO2-PCHPMA adsorbed cationic methylene blue (MB), but did not adsorb anionic methyl orange (MO) in their aqueous solutions. The adsorption efficiency for MB reached 99% within 5 min at 28 °C, and adsorbed MB could be recycled in 96% efficiency. The adsorption accelerated degradation of MB under UV irradiation. The degradation of anionic MO proceeded completely with TiO2-PCHPMA under UV irradiation, and the efficiency was not affected by the PCHPMA layer. TiO2-PCHPMA is potentially applicable as a material capable of selective removal and recovery of cationic dyes, and degradation of other dyes from industrial effluents

Green Synthesis and Catalytic Activity of Silver Nanoparticles Based on Piper chaba Stem Extracts

A green synthesis of silver nanoparticles (AgNPs) was conducted using the stem extract of Piper chaba, which is a plant abundantly growing in South and Southeast Asia. The synthesis was carried out at different reaction conditions, i.e., reaction temperature, concentrations of the extract and silver nitrate, reaction time, and pH. The synthesized AgNPs were characterized by visual observation, ultraviolet–visible (UV-vis) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), energy dispersive x-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy. The characterization results revealed that AgNPs were uniformly dispersed and exhibited a moderate size distribution. They were mostly spherical crystals with face-centered cubic structures and an average size of 19 nm. The FTIR spectroscopy and DLS analysis indicated that the phytochemicals capping the surface of AgNPs stabilize the dispersion through anionic repulsion. The synthesized AgNPs effectively catalyzed the reduction of 4-nitrophenol (4-NP) and degradation of methylene blue (MB) in the presence of sodium borohydride