The development of photocurable compositions is in high demand for the manufacture of functional materials for electronics, optics, medicine, energy, etc. The properties of the final photo-cured material are primarily determined by the initial mixture, which needs to be tuned for each application. In this study we propose to use simple systems based on di(meth)acrylate, polyimide and photoinitiator for the preparation of new photo-curable compositions. It was established that a fluorinated cardo copolyimide (FCPI) based on 2,2-bis-(3,4-dicarboxydiphenyl)hexafluoropropane dianhydride, 9,9-bis-(4-aminophenyl)fluorene and 2,2-bis-(4-aminophenyl)hexafluoropropane (1.00:0.75:0.25 mol) has excellent solubility in di(met)acrylates. This made it possible to prepare solutions of FCPI in such monomers, to study the effect of FCPI on the kinetics of their photopolymerization in situ and the properties of the resulting polymers. According to the obtained data, the solutions of FCPI (23 wt.%) in 1,4-butanediol diacrylate (BDDA) and FCPI (15 wt.%) in tetraethylene glycol diacrylate were tested for the formation of the primary protective coatings of the silica optical fibers. It was found that the new coating of poly(BDDA–FCPI23%) can withstand prolonged annealing at 200 °C (72 h), which is comparable or superior to the known most thermally stable photo-curable coatings. The proposed approach can be applied to obtain other functional materials.

Polydimethylsiloxanes with improved mechanical properties that can be processed by 3D printing are in high demand for scientific and practical applications. In our article, we proposed the synthesis of new PDMS copolymers with urethane and triazole fragments using the CuAAC reaction mechanism, as well as 3D printing with the obtained copolymers. Two types of copolymers, with molecular weights of 3000 and 6000 Da of PDMS block length, were prepared and characterized by GPC, IR spectroscopy, TGA, DSC, TMA, SAXS, and rheological measurements to determine their physicochemical properties. The synthesized copolymers were found to be suitable for processing by extrusion 3D printing. This demonstrated the ability to 3D print macroscale models of varying shapes and complexity. The resulting materials retained their printed shape over time.

The structure of organosilicon vinyl-containing boroxine was confirmed by 1H nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Its thermal properties were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) methods. The ability of boroxine to undergo hydrosilylation using the Karstedt's catalyst was investigated on various organosilicon substrates. Boroxine was shown to be involved in these reactions as a cross-linking agent. The formation of dynamic boroxine cross-links allowed the analysis of the reaction products by NMR spectroscopy, including the use of polyfunctional hydride-containing reagents. In all cases the addition proceeds selectively to the beta-position and with complete conversion. The structure of the resulting polyborosiloxane containing 1.4 mol% of modified units was also confirmed by 1H NMR spectroscopy, and its thermal and rheological properties were studied.

Starting from the functional cyclotriphosphazene, polysiloxane and nano-SiO2 precursors, three new hybrid nanocomposites with reinforced mechanical properties were prepared. Young's modulus values for all the composite samples are similar in the range of 7–11 MPa, stress at fracture increases with the nano-SiO2 content increase in the material and reaches a maximum value of 36 MPa for the composite with 20% nano-SiO2. The nanocomposites investigated are elastic and demonstrate the ability to be deformed without failure up to 54% strain.

In this work, a series of novel macrocycles and helicates based on organosilicon bis-dibenzoylmethane ligand have been synthesized and characterized as well as their structures have been determined by X-ray analysis, MS, NMR and UV-Vis spectroscopy. The thermal stability of the complexes was estimated by thermal gravimetric analysis (TGA). (C) 2020 Elsevier B.V. All rights reserved.