Template-dependent hydrophobicity in mesoporous organosilica films

A template dependence of the degree of self-hydrophobization of methylene-bridged periodic mesoporous organosilica (PMO) films is reported. The film with the smallest pore size of 1.7 nm, templated by CTAC, results in higher hydrophilicity when compared to films with a pore size of 4.1 or 5.3 nm, templated by BrijL4 and BrijS10, respectively. Both the surface and the bulk hydrophilicity were evaluated by water contact angle measurements and water ellipsometric porosimetry and the same trends were observed. Additionally, we provide the first evidence for a steric hindrance of the self-hydrophobization process. We show that a partial template removal results in the methylene-to-methyl transformation being observed at a temperature as low as 200 degrees C, significantly lower than previously demonstrated. These results should be taken into account when PMO materials are considered for applications such as low-k dielectrics, membranes, catalyst and chromatographic supports, and drug carriers

UV cure of oxycarbosilane low-k films

status: publishe

High Hopes for the Biofabrication of Articular Cartilage—What Lies beyond the Horizon of Tissue Engineering and 3D Bioprinting?

Technologies and biomaterials for 3D bioprinting have been developing extremely quickly in the past decade as they hold great potential in tissue engineering. This, together with the possibility to differentiate stem cells of different origin into any cell type, raises the hopes in regenerative medicine once again after the initial breakthrough with stem cells in the 1980s. Nevertheless, three decades of 3D bioprinting experiments have shown that the production of functional tissues would take a longer time than anticipated. Cartilage, one of the simplest tissues in the body, consists of only one cell type. It is not vascularised and innervated and does not have lymphatic vessels either, which makes it a perfect target tissue for successful implantation. The tremendous amount of work since the beginning of this century, combining the efforts of bioengineers, material scientists, biologists, and physicians, has culminated in multiple proof-of-concept constructs that have been implanted in animals. However, there is no single reproducible, standardised, widely accessible and accepted strategy that can be readily applied in the clinic. In this review, we focus on the current progress in the field of the 3D biofabrication of articular cartilage and critically assess failures and future challenges

Tuning the properties of periodic mesoporous organosilica films for low-k application by Gemini surfactants

Periodic mesoporous organosilica (PMO) thin films were synthesized by evaporation-induced self-assembly of 1,2-bis(triethoxysilyl)ethane and an ionic Gemini 16-12-16 surfactant under acidic conditions. The films were characterized by Fourier-transform infrared spectroscopy, grazing-incidence small-angle X-ray scattering, ellipsometric porosimetry, impedance measurements, and nanoindentation. The ease of control of the packing parameter in Gemini surfactants makes the PMO film templated by a Gemini an exciting first step towards small pore size PMO films with engineered mesostructures

On the mechanical and electrical properties of self-assembly-based organosilicate porous films

The effect of the replacement of Si-O-Si by Si-CH2-Si groups on the mechanical and electrical properties of silica-based hybrid sol-gel thin films is reported. For a reliable inference, two sets of organosilica films were synthesized - one consisting of a silica matrix decorated with methyl groups (Si-CH3) while the other further incorporating bridging methylene (Si-CH2-Si) functionalities. As a result, at the film density of 0.87 g cm(-3), a higher Young's modulus of 6.6 GPa was deduced for the film containing Si-CH2-Si groups compared to 5.3 GPa for the one with Si-O-Si functionalities. Concurrently, the introduction of the methylene bridging groups leads to a dielectric constant increase from 2.12 to 2.27. Furthermore, the type of surfactant, ionic or nonionic, employed as a templating agent has a negligible effect on the electrical properties and the reliability performance of the porous organosilica films