Surface modification of astralenes for obtaining optical composites based on photocurable acrylates

Polymers are a promising matrix for creating optical materials due to the possibility of imparting new properties to the material by introducing additives. In particular, astralenes, which are multilayer toroidal nanostructures, known as structure modifiers for some medium and also have nonlinear optical properties. Hower, the creation of an optical composite requires modification of the particle surface for uniform distribution of particles in the matrix. The two-stage modification technique developed by the authors allows reducing the amount of disordered carbon in the astralenes, as well as making them compatible with photocurable acrylic monomers. As a result, a transparent optical composite was obtained by photopolymerization. The success of the modification process is confirmed by the results of Raman and FTIR spectroscopy, TG analysis. The TEM method showed that the toroidal structure of the particles is preserved after the modification process. The study compared composites with 0.01, 0.05, 0.10%wt. astralenes and the original copolymer. It was found that the introduction of particles into the reaction mass reduces the polymerization rate by more than 40%. At the same time, the conversion degree in samples with and without astralenes is comparable. The transparency of the obtained composites in the visible region and NIR is comparable to the copolymer and is equal to ~ 90%. The introduction of astralenes in the selected concentrations does not significantly affect the optical band gap of the material.