Gold-Decorated Block Copolymer Microspheres with Controlled Surface Nanostructures

Gold-decorated block copolymer microspheres (BCP-microspheres) displaying various surface morphologies were prepared by the infiltration of Au precursors into polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) microspheres. The microspheres were fabricated by emulsifying the PS-b-P4VP polymers in chloroform into a surfactant solution In water, followed by the evaporation of chloroform. The selective swelling of the P4VP domains in the microspheres by the Au precursor under acidic conditions resulted in the formation of Au-decorated BCP-microspheres with various surface nanostructures. As evidenced by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) measurements, dotted surface patterns were formed when microspheres smaller than 800 nm were synthesized, whereas fingerprint-like surface patterns were observed with microspheres larger than 800 nm. Au nanoparticles (NPs) were located inside P4VP domains near the surfaces of the prepared microspheres, as confirmed by TEM. The optical properties of the BCP-microspheres were characterized using UV-vis absorption spectroscopy and fluorescence lifetime measurements. A maximum absorption peak was observed at approximately 580 nm, indicating that Au NPs are densely packed Into P4VP domains on the microspheres. Our approach for creating Au-NP-hybrid BCP-microspheres can be extended to other NP systems such as Iron-oxide or platinum NPs. These precursors can also be selectively incorporated into P4VP domains and induce the formation of hybrid BCP-microspheres with controlled surface nanostructures

Hydrogen bonding in supramolecular nanoporous materials

This chapter provides an overview of the use of hydrogen bonds for the construction of nanoporous materials. These materials attract a great deal of interest because of their large surface area to volume ratio and their applications in areas such as filtration, separation, adsorption, catalysis, and ion conduction. Organic materials are especially appealing for these applications, because their properties can be tailored. The use of supramolecular interactions is required to control the organization of materials at the molecular level. Hydrogen bonds are ideal supramolecular interactions for the construction of these nanoporous materials, thanks to their directionality and reversibility. The directionality causes the positioning molecules in such a way that voids have been created in between the molecules, such as in two- and three-dimensional hydrogen bonded organic frameworks. In a second approach, hydrogen bonded template molecules have been removed from a polymer to create pores. This method is successfully applied to hydrogen bonded block copolymers and liquid crystalline polymers