The objective of this CAREER award, co-funded by the Solid State and Materials Chemistry (SSMC) program and the Office of International Science and Engineering (OISE), is to understand a recently developed non-aqueous layer-by-layer (LbL) assembly of nanostructured thin films by studying the fundamentals of electrostatic interactions in non-polar media. This work bridges the fundamental investigation of electrostatic interactions between oppositely charged materials at the single particle level to the prediction of the composition and structure of nanostructured LbL thin films based on the charge characteristics of individual nanoparticles. The nature and significance of electrostatic interactions in non-polar media at the single particle level will be studied using atomic force microscopy, which will also reveal how the surface potential and charge of oppositely charged particles change at small separations. The thermodynamic nature of LbL assembly of oppositely charged materials in apolar solutions will also be investigated using isothermal titration calorimetry to uncover whether the nanoparticle assembly is an entropically or enthalpically driven process. Knowledge from these studies will be combined and translated to quantitatively predict and understand the composition and structure of LbL thin films based on the charge characteristics of individual nanoparticles.
NON-TECHNICAL SUMMARY: Nanostructured thin films are thin layers composed of multiple materials such as nanoparticles and polymers, and possess distinctive combinations of properties that make them useful for advanced applications such as energy conversion and storage. Layer-by-layer (LbL) assembly, which involves the sequential deposition of oppositely charged species, provides a simple yet versatile method for the generation of functional nanostructured thin films; however, this technique, to date, has been primarily used with water-soluble materials. This practice places a major obstacle to generating functional nanostructured thin films for alternative energy applications, because a large number of useful and unique nanomaterials are synthesized and stable in non-aqueous non-polar solvents only. The PI has recently successfully imparted surface charge to various nanomaterials in non-polar media and fabricated functional nanostructured thin films based on LbL assembly. The aim of this CAREER award is to understand the fundamental aspects of electrostatic interactions in non-polar solvents, which will further extend the new LbL technique for alternative energy applications. This CAREER award also integrates educational activities into the research plan with the goal of fully utilizing visual and hands-on aspects of layer-by-layer assembly to enrich the educational experiences of pre-college students and educators. Under-represented minority and female undergraduate students will participate in "Research Abroad" program at the Ulsan National Institute of Science and Technology in Korea, which will provide them with opportunities to broaden their view of the world and develop scientific communication skills.
