Colloids with Directional and Reconfigurable Interactions.

摘要

Colloidal particles hold great promise for atomic behavior modeling and the bottom-up self-assembly of micro-structured functional materials. Many structures dictated by packing criteria have been assembled from particles with various size and chemical composition. Complex or low-coordination structures, however, common in atomic and molecular systems, are rare in the colloidal domain due to a lack of directionality as well as reconfigurable colloidal bonding. This shortcoming limits the full potential of colloidal assemblies. The goal of this thesis is to fabricate colloids with directional and reconfigurable interactions that can be used as building blocks for complex colloidal architecture construction.;The fabrication of colloidal analogues of atoms is presented in chapter II: colloidal particles with chemically distinct and precisely located 'sticky DNA patches' on the surface that enable specific directional bonding. Using these colloidal 'atoms', a vast collection of colloidal 'molecules' and 'macromolecules' are readily accessible through self-assembly schemes that are analogous to chemical reactions.;To further assemble colloidal 'atoms' into colloidal crystals with complex structures, particles also need the ability to rearrange to minimize free energy. The engineering of colloidal interactions based on oligonucleotide hybridization is explored in chapter III. DNA-coated colloids that not only allow for directional self-assembly but can also rearrange to form large crystals are designed and synthesized. The crystallization process including nucleation, growth, aggregate restructuring, and defect formation of both single component and binary colloids are followed. The science described in chapter IV describes an alternative route to achieve directional and reconfigurable colloidal bonding via three-dimensional lock and key colloids. This strategy is based on shape complementary driven depletion interactions that are independent of the surface chemistry and chemical composition of the involved particles. In chapter V, future directions are described accompanied by preliminary results on fabricating DNA patchy particles with reconfigurable bonds that combines the work in chapters II and III. The colloids discussed in this thesis, with both directional and reconfigurable binding features, should give access to a rich variety of new micro-structured materials with unique photonic, catalytic and biological applications.