Synthesis Challenges and Strategies:
Integrated Molecular Systems
Dr. Jeff Brinker
Advanced Materials Laboratory
1001 University Boulevard S.E.
Albuquerque, NM 87106
(505) 272-7627
We are all fascinated with the exquisite design, construction, and function of natural materials like photosynthesis centers that very efficiently harvest light and sea shells that are simultaneously hard, tough, strong, and light weight. However from a materials perspective there are a number of synthetic challenges limiting our ability to impart to engineering materials the functional characteristics of natural systems. For example, how to efficiently combine hard and soft materials to arrive at robust devices wherein hard materials serve as a scaffolding to stabilize, orient, and mediate the performance of soft materials. Recently we devised a self-assembly strategy to co-organize inorganic (I) and organic (O) precursors into a variety of hybrid organic (polymer)-inorganic nanocomposites prepared with 1-, 2-, or 3-dimensional connectivity of the constituent phases. We used micelle formation to spatially partition and organize organic precursors (within the hydrophobic micellar interiors) and inorganic precursors (surrounding the hydrophilic micellar exteriors). Further self-organization of the micellar species into liquid crystalline mesophases efficiently organizes the organic and inorganic precursors into desired I/O nanocomposite forms. For example, in an attempt to mimic the nanolaminated construction of mollusk shells, we combined soluble silica, methacrylate monomers, thermal initiators, and a silane coupling agent (RíSi(OR)3 in an alcohol/water solvent. Preferential alcohol evaporation during dip-coating caused the partitioning of the hydrophobic monomers and initiators into the micellar interiors. Further evaporation induced self-organization of a lamellar mesophase created hundreds of alternating I/O layers in a single step. Thermally-initiated organic polymerization combined with continued inorganic polymerization locked-in the nanocomposite architecture and covalently bonded the organic-inorganic interface, resulting in the first self-assembled I/O nanolaminate.