High performance functional coatings, based on hybrid organic/inorganic materials, are being developed to combine the polymer flexibility and ease of processing with the mechanical properties and versatility of inorganic materials. By incorporating silica nanoparticles (SiNPs) in the polymeric matrices, it is possible to obtain hybrid polymer films with increased tensile strength and impact resistance, without decreasing the flexural properties of the polymer matrix. The SiNPs can further be used as carriers to impart other functionalities (optical, etc.) to the hybrid films. By using polymer-coated SiNPs, it is possible to reduce particle aggregation in the films and, thus, achieve more homogeneous distributions of the inorganic components and, therefore, better properties. On the other hand, by coating polymer particles with silica, one can create hierarchically structured materials, for example to obtain superhydrophobic coatings. In this review, we will cover the latest developments in films prepared from hybrid polymer/silica functional systems.

Metal nanoparticles can either quench or enhance the emission of dyes in their vicinity, but the precise measurement and understanding of this effect is still hindered by experimental artifacts, especially for particles in colloidal dispersion. Here, we introduce a new methodology to correct the inner filter effect of the metal on the dye emission. To test the method, we developed new hybrid nanoparticles with a gold core and a silica shell of precise thickness (tuned from 7 to 13 nm), with a high quantum yield perylenediimide dye on the surface. This novel approach effectively avoids fluorescence quenching, allowing us to measure emission enhancements of 5 to 30 times, with no change on the dye fluorescence lifetime. Being able to measure the emission enhancement in dye-metal hybrid nanoparticles in dispersion, free from inner filter and quenching artifacts, offers excellent prospects to guide the development of more efficient fluorescent probes, sensors and photonic devices.

Mesoporous silica nanoparticles (MSNs) are excellent nanocarriers, featuring very high cargo capacity due to their large surface area and pore volume. The particle and pore dimensions can be accurately tuned, and both the internal and external surfaces allow versatile functionalization. We developed hybrid MSNs with diameters around 140 nm, with the external surface selectively modified with a temperature-responsive biocompatible copolymer to control cargo release. The nanoparticles feature either a polymer brush or a gel-like responsive shell, produced by grafting from RAFT polymerization of PEG-acrylate macromonomers. The hybrid nanoparticles have fluorescent molecules incorporated into the inorganic network providing excellent optical properties for traceability and imaging. The cargo release profiles are explained by a temperature-controlled “pumping” mechanism: at low temperature (ca. 20 °C) the polymer shell is hydrophilic and expanded, opposing cargo diffusion out of the shell and retaining the molecules released from the mesopores; above room temperature (ca. 40–50 °C) the polymer network becomes more hydrophobic and collapses onto the silica surface, releasing the cargo by a sponge-like squeezing effect. The release kinetics depends on the polymer shell type, with better results obtained for the gel-coated nanoparticles. Our proof-of-concept system shows that by modulating the temperature, it is possible to achieve a pumping regime that increases the release rate in a controlled way.