Vivian Rebbin

Membrane morphology modifications induced by hydroquinones.

We synthesize and characterize alkylthiohydroquinones (ATHs) in order to investigate their interactions with lipid model membranes, POPE and POPC. We observe the formation of structures with different morphologies, or curvature of the lipid bilayer, depending on pH and increasing temperature. We attribute their formation to changes in the balance charge/polarity induced by the ATHs. Mixtures of ATHs with POPE at pH 4 form two cubic phases, P4(3)32 and Im3m, that reach a maximum lattice size at 40 °C while under basic conditions these phases only expand upon heating from room temperature. The cubic phases coexist with lamellar or hexagonal phases and are associated with inhomogeneous distribution of the ATH molecules over the lipid matrix. The zwitterionic POPC does not form cubic phases but instead shows lamellar structures with no clear influence of the 2,6-BATH.

Periodic mesoporous organosilicas spheres: Novel synthesis and characterisation

Abstract Monodispersed spherical periodic mesoporous organosilicas (sph-PMOs) with high specific surface areas and narrow pore size distributions were synthesised in a modified Stober-reaction using long-chain tetraalkylammonium surfactants under alkaline conditions and 1,2-bis(trimethoxysilyl)ethane (BTME) and 1,4-bis(triethoxysilyl)benzene (BTEB) as bridged organosilica precursor. The synthesis leads to particles with an average size of 0.5 μm. The sph-PMOs were characterised by powder X-ray diffraction (P-XRD), Nitrogen physisorption, Raman spectroscopy SEM and TEM.

Periodic Mesoporous Organosilicas PMOs with Different Organic Bridging Groups: Synthesis and Characterization

We present results on new periodic mesoporous organosilicas synthesized with 1,4-bis(triethoxysilyl)benzene (BTEB), 1,2-bis(trimethoxysilyl)ethane (BTME) and bis[3-(trimethoxysilyl)propyl]amine (BTMPA). The materials show high inner surfaces up to 830 m 2 /g and pore diameters in the range of 2.7 to 3.7 nm depending on the structure directing agent used. In case of BTEB as precursor and triblock copolymer Pluronic P123 as structure directing agent exceptional thick pore walls were obtained (7.2 nm). Characterization was carried out by P-XRD, nitrogen physisorption analysis, thermoanalytical methods and IR spectroscopy.

Selective Adsorption of Solvents in a Multiscale Device

We have incorporated microspheres, 50 μm to 80 μm in diameter, of periodic mesoporous organosilica (inner surfaces up to 1000 m2 /g and pore sizes in the nanometre range) with two types of organic functionalities (benzene and ethane bridges, respectively) inside microstructured channels (each 200 μm wide and 100 μm deep) and, exemplarily, monitored by Raman microscopy that the temperature characteristics of the adsorption-desorption equilibria of benzene and ethanol vary significantly with the type of organic functionality of the microspheres and the pore morphology. The integration of this class of nanostructured material into devices by means of microchannels is a promising novel approach to, among others, substance separation in analytics, micro process engineering, and micro chemistry.Copyright