Oriented nanoporous lamellar organosilicates templated from topologically unsymmetrical dendritic-linear block copolymers.
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Biomedical subjects
Publications and source records attributed to Teddie Magbitang.
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Materials with nanometer size heterogeneities are commonplace in the chemical and biological sciences (e.g, polymer blends, microemulsions, gels) and often exhibit complex morphologies. Although this morphology has a dramatic effect on the materials' properties, it is often difficult to accurately characterize. We describe a method, using small-angle X-ray scattering data, of generating representative three-dimensional morphologies of isotropic two-phase materials where the morphology is disordered, and we apply this to thin films containing nanometer sized pores with a range of porosities (4-44%). These representations provide a visualization of the pore morphology, give the pore size scale and extent of interconnection, and permit the determination of the transitions from closed pore to interconnected pores to bicontinuous morphology.
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The distinctive features of well-defined, three-dimensional macromolecules with topologies designed to enhance solubility and amplify end-group functionality facilitated nanophase morphologies in mixtures with organosilicates and ultimately nanoporous organosilicate networks. Novel macromolecular architectures including dendritic and star-shaped polymers and organic nanoparticles were prepared by a modular approach from several libraries of building blocks including various generations of dendritic initiators and dendrons, selectively placed to amplify functionality and/or arm number, coupled with living polymerization techniques. Mixtures of an organosilicate and the macromolecular template were deposited, cured, and the phase separation of the organic component, organized the vitrifying organosilicate into nanostructures. Removal of the sacrificial macromolecular template, also denoted as porogen, by thermolysis, yielded the desired nanoporous organosilicate, and the size scale of phase separation was strongly dependent on the chain topology. These materials were designed for use as interlayer, ultra-low dielectric insulators for on-chip applications with dielectric constant values as low as 1.5. The porogen design, chemistry and role of polymer architecture on hybrid and pore morphology will be emphasized.