(4ch) Towards Targeted Molecular Design of Functional Materials

Molecular design and controlled synthesis of molecules with specific properties will create new classes of smart materials in the upcoming century.  By manipulating the forces between molecules, researchers can control both the microscopic and macroscopic behavior of materials in a way that would have seemed like science fiction just decades ago. The interactions between molecules can be tuned by varying hydrogen bonding, charge, rigidity, architecture etc… How do we sort through this plethora of possibilities to attain a molecule that achieves a desired goal? The three general approaches are theory, simulation and experiment. Synthetic chemistry is advancing at a blistering pace, giving researchers the ability to design ever more complex molecules to achieve specific goals; however, these design processes are very time consuming and expensive. With the infinite parameter space available for manipulation, experiment needs to be complimented by other cheaper and faster methods. These methods are theory and molecular simulation (MS), which allow for a rapid exploration of parameter space to target specific molecular structures as candidates for more expensive and time consuming experimental design. With the rapid increase in computational ability MS has become an important and widely used tool; however, the use of MS introduces another set of problems. To obtain reliable answers using MS, one must obtain good statistical sampling which can prove very difficult in many important situations. For instance, MS has difficulty with dilute components (such as the bulk surfactant concentration in an oil / water interface) and strongly associating systems (such as patchy colloids at low temperatures). Theoretical methods have no such handicap. Another advantage theory has over molecular simulation is speed of calculation. A significant challenge in developing molecular level theory for complex fluids is the anisotropy of interactions between molecules. However, advances over recent years have opened the door for model development models which account for various shape and interaction anisotropies. In this paper I review my recent contributions to the field of complex fluid theory. Specifically, I demonstrate how theory can be developed and applied to predict the interfacial properties and structure of the oil / water interface, how rod – coil copolymers align at liquid interface, and the structure and thermodynamics of patchy colloid fluids.