КОЛЛОИДНО-ХИМИЧЕСКИЕ СВОЙСТВА КРЕМНИЙОРГАНИЧЕСКИХ ПАВ, ПРИМЕНЯЕМЫХ В СИНТЕЗЕ ПОЛИСТИРОЛЬНЫХ ЛАТЕКСОВ

The synthesis of polymeric suspensions with a narrow particle size distribution is an urgent problem in modern science. The resulting polymeric microspheres are applicable in various fields of chemistry, pharmaceuticals, biology and medicine. In particular, they can be used as carriers of bioligands to create diagnostic test systems. This article presents the results of a study on the colloid-chemical characteristics of water-insoluble fluorinated silicone surfactants and kinetics of the polymerization process in their presence. The results were compared with data from studies on the properties of surfactants of similar structure not containing fluorine atoms in their structure. Studying these substances’ rheology enabled to determine the most suitable surfactants for adsorption forming a strong interfacial layer during the formation of polymermonomer particles during the polymerisation. The ability of fluorinated silicone surfactants to form a stable polymeric slurry was proved during heterophase polymerization of vinyl monomers. The resulting polymeric suspensions were characterized by a narrow particle size distribution and high aggregative stability during the synthesis and in storage.Синтез полимерных суспензий с узким распределением частиц по размерам является актуальной проблемой в современной науке. Полимерные микросферы применимы в различных отраслях химии, фармацевтики, биологии и медицины, в качестве носителей биолигандов при создании диагностических тест-систем. В работе приведены данные по изучению коллоидно-химических характеристик нерастворимых в воде фторированных кремнийорганических поверхностно-активных веществ (ПАВ) и кинетики процесса полимеризации в их присутствии. Изучение реологии данных веществ позволило определить наиболее подходящее ПАВ для формирования прочного межфазного адсорбционного слоя при образовании полимерно-мономерных частиц в процессе полимеризации. Способность фторированных кремнийорганических ПАВ образовывать стабильные полимерные суспензии была доказана при проведении гетерофазной полимеризации виниловых мономеров. Полученные полимерные суспензии характеризовались узким распределением частиц по размерам, а также высокой агрегативной устойчивостью в процессе синтеза и при хранении

Influence of the Surface Roughness of a Silicon Disk Resonator on Its Q-Factor

This article presents a silicon disk resonator of the whispering-gallery-mode (WGM) type. The calculated Q-factor of the silicon WGM resonator was 107. Two methods of studying the surface roughness of a silicon WGM resonator with a nonlinear profile by means of Helios 650 scanning electron microscope and Bruker atomic force microscope (AFM) are presented. The results obtained by the two methods agreed well with each other. A comparison of the surface roughness values of WGM resonators manufactured using different technological approaches is presented. Based on the obtained data, a preliminary estimated Q-factor calculation of the resonators was performed, which was refined by numerical calculation using the finite-difference time-domain (FDTD) method. The effect of the surface roughness of the resonator on its Q-factor was found. Reducing the surface roughness of the resonator from 30 nm to 1–2 nm led to an increase in its Q-factor from 104 to 107

Hydrothermal epitaxy growth of self-organized vanadium dioxide 3D structures with metal–insulator transition and THz transmission switch properties

The hydrothermal method is the most effective approach for the synthesis of VO2 metastable polymorphs with unique powder crystallite morphology. In this work, we expanded the capabilities of this method, directing it to the growth of oriented crystallites in self-organized systems on single crystal substrates. According to our investigations, a large variety of 3D structures of vanadium dioxide can be obtained using one single crystal substrate r-sapphire by fine tuning of synthesis parameters. The orientation growth of six-pointed vanadium dioxide crystallites fits into an epitaxial growth model describing unit cell relations between the VO2(M1) film and r-sapphire substrate. We describe the process of VO2(M1) phase stabilization in the films and the changes of resistivity and terahertz transparency of the films based on the metal–insulator transition (MIT)

COLLOID-CHEMICAL PROPERTIES OF SILICONE SURFACTANTS USED IN THE SYNTHESIS OF POLYSTYRENE LATEXES

The synthesis of polymeric suspensions with a narrow particle size distribution is an urgent problem in modern science. The resulting polymeric microspheres are applicable in various fields of chemistry, pharmaceuticals, biology and medicine. In particular, they can be used as carriers of bioligands to create diagnostic test systems. This article presents the results of a study on the colloid-chemical characteristics of water-insoluble fluorinated silicone surfactants and kinetics of the polymerization process in their presence. The results were compared with data from studies on the properties of surfactants of similar structure not containing fluorine atoms in their structure. Studying these substances’ rheology enabled to determine the most suitable surfactants for adsorption forming a strong interfacial layer during the formation of polymermonomer particles during the polymerisation. The ability of fluorinated silicone surfactants to form a stable polymeric slurry was proved during heterophase polymerization of vinyl monomers. The resulting polymeric suspensions were characterized by a narrow particle size distribution and high aggregative stability during the synthesis and in storage