Self-assembly, complex fluids, nanomaterials, interfacial phenomena, amphiphilic polymers

Paschalis Alexandridis, Professor

Nanoscale organization via self-assembly and directed assembly

Prof. Paschalis Alexandridis and his research group work to capitalize on the ability of amphiphilic, dual-nature, molecules to organize themselves into complex assemblies with structures from the nanoscale to the macroscale.

Self-assembly is an energy-efficient process (it occurs spontaneously) and can lead to products that are functional, responsive, and high value-added. All living creatures bear manifestations of self-assembly (e.g., cell membranes, collagen), and numerous technical products and processes take advantage of properties afforded by the self-assembly of surfactants, polymers, and/or colloidal particles. Properties imparted by self-assembly include compartmentalization, compatibilization, network formation, and surface modification.

The development of self-assembly as a useful approach to the synthesis and manufacturing of complex systems and materials is identified as a “Grant Challenge” according to the 2003 National Research Council report “Beyond the Molecular Frontier”. Alexandridis' research program, funded by NSF and industry and resulting in over 100 publications and 2 patents over the past 10 years, is tackling this grant challenge.

Self-assembly takes place spontaneously when the “right” components are at the “right” conditions, but things are not that simple.

• What are the “right” components and the “right” conditions? Alexandridis utilizes commercially available amphiphilic molecules and develops formulations with desirable structure-property relations that are tailored for specific applications, e.g., pharmaceutics and personal care products, there the ingredients allowed are tightly regulated, or coatings and inks, where environmental considerations restrict the kinds of solvents used.
• What if the conditions are no longer “right”? Alexandridis investigates ways to arrest the self-assembled structure and determines the kinetics of structure formation and dissolution. This is relevant to the synthesis of nanomaterials where the self-assembled structure serves as a template, but the synthesis conditions and/or by-products disturb the self-assembly. It is also relevant to the shelf-life of products that incorporate self-assembled components.
• How can we “help” self-assembly? Alexandridis explores external fields, flow and electric, to orient self-assembled structure over macroscopic length scales, and to collect and organize nanoparticles in a hierarchical manner. The combination of self- and directed assembly has great potential in nanotechnology applications such as sensing, actuation, synthesis of nanocomposite and/or biomimetic materials.