Melamine [HRP]

Melamine formaldehyde (MF) is a versatile and widely used chemical cross-linking agent in microcapsule shells for the encapsulation of oil phases in an aqueous continuum. However, it has not been possible to form MF microcapsules with water soluble actives, to achieve sustained/no release in aqueous environment. Herein, 5 types of MF based microcapsules were designed and synthesised with 4 polymers, including neutral and polar poly(acrylamide-acrylic acid), anionically charged biocompatible shellac and ion exchange resin polystyrene sulfonate as well as a superhydrophobic polymer precursor octadecyltrichlorosilane, via an in situ polymerisation method. Potassium chloride and allura red (dye, Mw = 496.42 g.mol(-1)) were used as models of inorganic and organic water soluble actives with low molar mass, respectively, to study their size distributions, encapsulation efficiencies, payloads, morphologies and release rates in aqueous environment. The release rates ranged from complete release within 15 min to no release up to 1 month in aqueous environment. (c) 2020 Elsevier Ltd. All rights reserved.

Nano-hexagonal boron nitride (h-BN) was successfully prepared via rapid microwave-assisted synthesis using boric acid (H3BO3) and melamine (C3H6N6) as raw materials. An investigation of the effect of the microwave energy on the synthesis process of nano h-BN was carried out. In addition, the preparation method of the precursor was also studied. Here, mixtures at different H3BO3:C3H6N6 ratios (1:1 and 2:1 M) were prepared via wet and dryforms. Each precursor was heated under microwave energy for different reaction times. The microwave-synthesized nano-products were characterized by XRD, SEM, EDS, HRTEM and SAED. The results show that the reaction time and temperature that are typically 4.6 h (ramp time + soak time) and 1400-2100 degrees C, respectively (literature values), can be dramatically reduced to only 1.5 h (ramp time + soak time) and 1130-1210 degrees C, respectively, applying microwave heating. It was observed that the final product consists of crystalline h-BN nanoparticles of about 20 nm and disc-like morphology. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.