Autoensamblado de nanoestructuras mediante separación de fases inducida por polimerización

R.J.J. WILLIAMS

Buenos Aires

Congreso; XIX Congreso Argentino de Físicoquímica y Química Inorgánica; 2015

Asociación Argentina de Investigadores en Físicoquímica y Química Inirgánica

Linear polymers, block copolymers or nanoparticles stabilized by organic ligands can be dissolved in a reactive solvent constituted by the precursors of a cross-linked polymer. In most cases, phase separation takes place during polymerization mainly due to the significant decrease of the entropic contribution to the free energy of mixing. By an adequate selection of the starting formulation and reaction conditions, the segregated phase self-assembles forming ordered arrays. A large variety of nanostructured architectures generates during polymerization of block copolymer / epoxy blends. A combination of TEM and in situ SAXS enabled to follow the evolution of nanostructures with the conversion in the polymerization reaction. For a particular system, the morphology evolved from a dispersion of spherical micelles to bcc structures, chains of spherical micelles, cylindrical micelles and hexagonally-packed cylinders. Selecting the polymerization conditions enabled to convey the process to obtain desired morphologies. Nanoparticles initially dispersed in a reactive solvent produce different structures upon polymerization. These include crystalline platelets, fractal arrays of colloidal crystals or the patterning of nanoparticles in polymer films. Generation of physical or covalent bonds between the organic ligands and the polymer network avoids phase separation or reduces it to a local region. This strategy was used to synthesize shape memory epoxies that could be activated by a magnetic field or by laser irradiation.