1,721,001 research outputs found
Nanostructured films and templates from self-assembling polystyrene based block copolymers
No full textBlock copolymers micellization for the synthesis of mesoporous silicas: a sol-gel approach
No full textDurability of acrylic films from commercial aqueous dispersion: glass transition temperature and tensile behaviour as indexes of photooxidative degradation
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Develpment of highly selective silica membranes obtained by using PS-b-PEO as templates
No full textHighly selective membranes with controlled morphology can be obtained by growing thin mesoporous oxide films on
an appropriate support. This can be achieved employing organic/inorganic mixed micellar solutions based on the use of
proper templates.
Amphiphilic block copolymers are very attractive materials for soft-templating. When mixed with organic solvents
selective for one of the blocks, they can self-assembly into micelles with the insoluble blocks constituting the micellar
core and the soluble ones the corona.
The silica porous membranes described in this contribution were obtained by sol-gel reaction of a silicon oxide
precursor (TEOS) and using polystyrene-block-poly(ethylene-oxide) (PS-b-PEO) copolymers as templates.
Morphology and size of the self-assembled micelles and of the final porous oxide depend both on composition
parameters (such as the length and nature of the polymer blocks) and on solution parameters (such as the
hydrophilic/hydrophobic balance between solvents and cosolvents).
This contribution focuses on the effect of composition parameters, namely the chain length of each polymer block, the
stoichiometric ratio of the monomers, and the polymer/silica ratio. By changing these parameters silica structures with
narrow pore size distribution and pore shapes ranging from spheres to channels were obtained.
The final goal of this research will be the preparation of silica membranes with controlled and high porosity to be
applied in the field of microfluidic analyses (e.g. Lab-on-a-chip devices) and as selective gates in microchip-based
technologies for separation, detection and dosing of molecular or ionic species, charged nanoparticles and biomolecules
Synthesis of mesoporous silica films by block copolymers micellization
No full textHighly selective silica membranes with controlled porosity can be obtained by employing organic/inorganic mixed micellar solutions based on the use of commercial templates. Amphiphilic block copolymers are very attractive materials as structure directing agents. When mixed with organic solvents selective for one of the blocks, they can self-assemble into micelles with the insoluble blocks constituting the micellar core. The morphology and size of self-assembled micelles depend on the size (length) and nature (polarity) of the templates blocks, and on solution parameters. Silica porous films described in this contribution are obtained by sol-gel reaction of tetraethyl orthosilicate (TEOS) using polystyrene-block-poly(ethylene-oxide) (PS-b-PEO) copolymers as templates. In order to modulate pore sizes and alignment in the final material, many different variables are changed: e.g., block copolymer chain length, block copolymer/TEOS ratio, solvents, hydrophilic/hydrophobic solvent ratio and use of additives (i.e. polystyrene homopolymer). To obtain an oxidic mesoporous membrane, the block copolymer/TEOS micellar solution is deposited on inorganic supports via spin-coating. The spin coating conditions used ensure fast evaporation of solvents, freezing in the solid state the micelles shape present in solution. Block copolymer micelles are finally removed by thermal degradation in air, leaving an amorphous porous material which can be applied in the field of microfluidics for separation, detection and dosing of molecules, ions, charged nanoparticles or biomolecule
Synthesis and physico-chemical characterization of porous silica membranes obtained by using PS-b-PEO block copolymers as soft templating agents
No full textHighly selective membranes with controlled porosity can be obtained by growing thin films of mesoporous oxides on an appropriate support. This can be achieved employing organic/inorganic mixed micellar solutions based on the use of commercial or ad hoc designed templates. Amphiphilic block copolymers are very attractive materials as soft-templating agents. When mixed with organic solvents selective for one of the blocks, they can self-assemble into micelles with the insoluble blocks constituting the micellar core and the soluble ones the corona. The morphology and size of self-assembled micelles depend on the size (length) and nature (polarity) of the blocks, and on solution parameters. Silica porous membranes described in this contribution were obtained by sol-gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene-oxide) (PS-b-PEO) block copolymers as templates. In order to modulate pore sizes and alignment of the final material, many different variables were changed: e.g. block copolymer chain length, block copolymer/TEOS ratio, type of solvents, solvent ratio and use of additives (i.e. polystyrene homopolymer). Aim of the present work is the preparation of silica membranes with narrow pore size distribution and high porosity to be applied in the field of microfluidic analyses and as selective gates in microchip-based technologies for separation, detection and dosing of molecular or ionic species, charged nanoparticles or biomolecule
Porous and worm-like titanium dioxide nanostructures from PS-b-PEO block copolymer micellar solutions
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