A method for obtaining a new type of silicones under "green" conditions is proposed
Russian scientists have developed a new method for producing a special class of organosilicon compounds – siloxanols. It will make it possible to create substances using cheap and safe reagents, at room temperature and atmospheric pressure, using molecular oxygen. The obtained siloxanols open up prospects for the creation of unique mechanically strong, self-healing, electrically conductive and other materials. The results of the research were published in the journal Green Chemistry, and were also presented at the VI scientific youth school-conference “Chemistry, Physics, Biology: Ways of Integration” and the XIV Andrianov Conference.
The materials, collectively known as silicones, or siloxanes, are composed of alternating oxygen and silicon atoms. With relatively small volumes of production, they ensure the development of aviation and space apparatus engineering, electronic technology, and are of great importance for creating a comfortable human environment. Such a wide area of application of silicone materials is associated with their unique properties: resistance to low and high temperatures, radiation, compatibility with biological tissues, and so on.
Despite all these advantages, silicones have significant disadvantages that narrow the area of their application: low mechanical strength and incompatibility with organic polymers. This is due to the very weak intermolecular interaction between the chains of such compounds. If we add so-called polar functional groups to the chain, for example, hydroxyl (-OH), then it is possible to enhance the intermolecular interaction of polymer chains and, as a consequence, to impart mechanical strength to the material. However, most of the existing methods either do not allow the introduction of a polar functional group due to the harsh conditions of the process, or are unacceptable due to the high cost, commercial unavailability, and toxicity of the reagents.
The authors of the new study have found an efficient way to obtain siloxanes with a polar hydroxyl group – siloxanols – under conditions of aerobic oxidation of certain types of commercially available siloxanes. A new technique that allows one to obtain siloxanols according to the principles of “green” chemistry (reducing the negative impact on the environment to a minimum) is described in a study by scientists from the Institute of Organoelement Compounds (INEOS) named after A.N. Nesmeyanov RAS in collaboration with scientists from the Institute of Synthetic Polymeric Materials named after N. Enikolopov and the Institute of Molecular Biology named after V.A. Engelhardt RAS.
“One of the most attractive approaches to solving these problems is the aerobic oxidation processes – processes in which oxygen serves as an oxidizing agent or a source of an oxygen atom in the final product. Using the processes of aerobic oxidation under mild conditions – room temperature, atmospheric pressure – with the use of cheap and commercially available reagents, both new and industrially important products can be obtained. A number of industrially important processes are based on this method, ”said one of the authors of the study, Ashot Arzumanyan, senior researcher at the K.A. Andrianova INEOS RAS.
Scientists have proposed a universal and simple approach to the introduction of a hydroxyl group into siloxanes, which will make it possible to create unique silicone materials with high mechanical strength, compatibility with organic polymers, the possibility of self-healing, electrically conductive, liquid crystal and other properties. According to the authors, their development is on the way to obtaining hybrid siloxanes for a new generation of high-tech devices, devices and mechanisms.
“In our work, we have proposed a highly efficient method for the synthesis of organosilicon products – siloxanols, which is based on the oxidation of the corresponding hydridesiloxanes with oxygen. This approach is based on “green”, commercially available, cheap, simple reagents and mild reaction conditions: atmospheric pressure and temperature 25–60 ℃. The reaction is common to obtain both monomeric and polymeric siloxanols of various structures: linear, branched and cyclic. Using this method, both described and previously undescribed siloxanols were obtained. Thus, the transition to “green” reactionary conditions turned out to be not only a fundamentally important environmental decision, but also, perhaps, the most promising from a synthetic point of view for fulfilling the assigned tasks, “the scientist add
ed. Source: indicator.ru