435393 Programmable Dynamic Materials As Information Carriers

Sunday, November 8, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Fateme Sadat Emami, Chemical Engineering, Northwestern University, Evanston, IL

Interfacial properties dictate interactions and communications of every existing specie with its surrounding environment. Controlling interfacial chemistry of materials and its response to external stimuli such as light, stress, humidity, temperature, electric or magnetic field, pH, or ionic strength can be a pathway to attain unique functionalities. Nature provides abundant examples of processes that are triggered by interfacial stimulants. Interfacial dynamic response to the external stimuli could lead energetic and conformational transformation or might yield highly controlled material fabrication. Examples are plentiful; some instances include: plants capable of dynamically reform their conformation by light or subtle physical forces, animals that harmonize their skin color with their environment, human eyes pupils’ expansion and dilation with light, hierarchical microorganisms formed under perfect control of layers’ interfacial chemistry, and many more.

My research theme is to design systems with controllable dynamics that are responsive to external stimuli in order to deliver work, material, or information of any kind. Once stimulus is applied to a material including segments with sensory receptor, a reflex occurs via energetic transformation from one state to another. This transducing between certain eigenstates can then be transformed into a cascade of events to elicit desired functionalities.

The key to successful design of smart systems is the suitable choice of a structure core that can undergo conformational variation upon applying external trigger. Grafting head groups with contrasting properties can then lead to achieve dynamically interchangeable characteristics such as electric charge, wettability, specific affinity in order to transfer matter (at different scales), capture and release ions, for self-cleaning purposes, and many more. The energetic stability of transferrable eigenstates and the hysteresis will then determine the efficiency of these systems.

There are many possibilities to design smart systems with increasingly fascinating capabilities. Few from many include: smart membranes made of nano-valves that allow unidirectional transfer of molecules or ions “on-demand”, charge inversion of colloids, smart polymeric material that are sensitive to external chemical composition usable for simple medical diagnosis, and touch-sensitive polymers applicable as artificial skin.

For all above, I will apply theoretical modeling and simulations, thermodynamics, and statistical mechanics approaches to understand surface-dynamic phenomena at the level of fundamental thermodynamics. Nonequilibrium actuation, characteristic response times, and energetic efficiencies will be studied by theoretical and simulation techniques.

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