Reactive blends derived from modified soybean oil and silicone

Reactive blends prepared from methoxysilane terminated silicone polymers and silylated soybean oil are described and characterized. Although simple mixing of soy and silicones results in gross phase separation, homogeneous polymeric products are obtained by introducing reactive sites. These products can be used as protective coatings, additives to adhesives and new sealants. Exposure of the mixtures to moisture leads to hydrolysis of the methoxysilanes and subsequent condensation of the resulting silanols that yields stable siloxane linkages between the two immiscible phases. FTIR, TGA, and swell‐gel analyses indicate effective formation of these siloxane crosslinks. Reactive blends containing less than 20% silylated oil appeared completely transparent but increasing the soy content decreased the optical transparency. SEM micrographs reveal the silicone polymer as the continuous phase with individual spherical silylated soy oil particles distributed in it. The properties of these reactive blends vary from high elongation elastomers to high modulus resins depending on the composition. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3086–3093     

An Improved Procedure for Hydrosilation of α,β-Unsaturated Esters and an Extension to Conjugated Diene Esters

Treatment of α,β-unsaturated esters with triethylsilane in benzene in the presence of a catalytic amount of tris(triphenylphosphine)rhodium chloride at room temperature followed by chromatography on silica gel gave rise to the corresponding saturated esters. Under similar conditions, fully conjugated diene esters were reduced to the dihydrolevel to give β,γ- or γ,δ-unsaturated esters depending upon the substitution pattern of the starting substrate.     

Trifluoroethanol and liquid-assisted grinding method: a green catalytic access for multicomponent synthesis

Research on Chemical Intermediates - An efficient and versatile mechanochemical route for the synthesis of chromene and isoindolo[2,1-a]quinazoline scaffolds has been developed via a simple mortar...     

Rationalisation of extractive protocol by high-performance thin-layer chromatographic–densitometric quantification of berberine in multiple hydroalcoholic extract of Tinospora cordifolia stem

JPC – Journal of Planar Chromatography – Modern TLC - Drug development from medicinal plants by using various hydroalcoholic solvents has been an emerging trend in the last few decades....     

Thermal degradation kinetics and reaction models of 1,3,5-triamino-2,4,6-trinitrobenzene-based plastic-bonded explosives containing fluoropolymer matrices

In this article, thermal degradation behavior of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based plastic-bonded explosives (PBXs) bonded with a different fluoropolymer matrices namely indigenous poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM), FK 800, fluoroplastic F-32L and fluororubber SKF 32 was investigated through non-isothermal thermogravimetric analysis (TG) technique under nitrogen atmosphere. It was observed that the mass loss of PBXs containing FKM and FK 800 matrices occurred in three steps. The mass loss of PBXs containing fluoroplastic F-32L and fluororubber SKF 32 occurred in two steps. Kinetics were investigated through non-isothermal TG at different heating rates for the first step of degradation by means of model-free Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. The activation energies calculated by applying FWO method are in good agreement and very close to those obtained by KAS method. The results revealed that the effect of the polymer matrices on the thermal degradation reaction of TATB was significantly observed especially different outcomes of kinetic parameters. The reaction models for degradation were also studied by Criado method. The reaction models are probably best described by the power law and diffusion models.     

pH-responsive non-surface-active/surface-active transition of weakly ionic amphiphilic diblock copolymers

The weakly ionic amphiphilic diblock copolymer polystyrene-b-poly(acrylic acid) was synthesized by nitroxy radical-mediated living radical polymerization with precise control of block length, block ratio, and polydispersity. Systematical surface tension experiments and foam formation observations revealed that this polymer was non-surface active under neutral and alkaline (pH 10) conditions, while it was surface active under an acidic condition (pH 3). This result supports our proposed origin of non-surface activity; the image charge repulsion at the air/water interface is essential in addition to very stable micelle formation in the bulk solution. At a higher pH (pH 12), the polymer showed slight surface activity since the added NaOH played a role as an added salt. The critical micelle concentration (cmc) was estimated by static light scattering. Cmc increased with increasing added salt (NaCl) concentration as was observed for other strongly ionic non-surface-active polymers. Hence, this trend is characteristic for non-surface-active polymers. The pH dependence of cmc was minimum at pH 8–10. Since the acrylic acid block is fully ionized under this condition, the strong image charge repulsion at this condition accelerated micelle formation at a low polymer concentration, which consequently decreased cmc. Micelles in bulk solution were confirmed by dynamic light scattering, and the salt concentration and pH dependencies of the hydrodynamic radius of the micelles were also estimated. The pH-responsive non-surface-active/surface-active transition observed in this study strongly supports the fact that the image charge repulsion is an essential factor for non-surface activity in addition to stable micelle formation in solution.     

Bio-surfactant: a green and environmentally benign reaction medium for ligand-free Pd-catalyzed Mizoroki–Heck cross-coupling reaction in water

Transition Metal Chemistry - A simple and efficient protocol for the ligand-free Mizoroki–Heck coupling reaction of various aryl bromides with different olefins has been reported by using in...     

Highly efficient deprotection of aromatic acetals under neutral conditions using beta-cyclodextrin in water

Aromatic acetals have been deprotected to the corresponding aldehydes under biomimetic conditions for the first time using beta-cyclodextrin in water under neutral conditions, thereby overcoming many of the drawbacks associated with earlier methodologies. This method, apart from being simple with regard to recycling of the catalyst, also has the potential for industrial applications.