Hybrid organic/inorganic materials for photonic applications via assembling of nanostructured molecular units

Abstract

Hybrid organic–inorganic materials exhibit so versatile properties that they can be considered one of the most interesting classes of materials for photonic applications, for the development of both passive and active devices. A synthetic route used for the preparation of nanostructured organic/inorganic (O/I) materials is the assembling of nano-building blocks (NBBs). This approach allows controlling the extent of phase interaction, which in its turn governs the structure-properties relationships. The non-hydrolytic sol–gel process is recognized as a useful route for the preparation of nanostructured molecular units. The condensation reaction of methacryloxypropyl trimethoxysilane and diphenylsilanediol in a non-hydrolytic sol–gel process has been exploited in order to synthesize nanostructured molecular units for the preparation of hybrid organic/inorganic coatings. The non-hydrolytic condensation reactions were run adding different compounds such as triethylamine, titanium isopropoxide, titanium chloride, and dibutyldilauryltin as condensation promoters. The NBB synthesis was also run under controlled hydrolitic conditions, by exploiting the in situ water production using an ethanol/acetic acid mixture. These reactions have been compared in terms of the influence of the employed reagents on the condensation degree and the product structure. Multinuclear NMR, ATR-FTIR and FT-Raman techniques have been used to study the reaction steps and characterize the final condensation products. Hybrid O/I materials have been prepared by assembling methacrylate-based NBBs in the presence of suitable thermal and photo-initiators. The study on the progress of the thermal polymerization process using differential scanning calorimetry (DSC) will be presented, as well as the preliminary results on the two photon polymerization (TPP) process for the preparation of patternable films.