Dimitris Priftis, Ph.D.

The intelligent use of processes such as self-assembly, combined with the ability to manipulate the chemical structure of polymers, can lead to a wide array of new materials. Such functional materials could be a solution to many of the challenges that the modern world faces, including improved biomedical devices and strategies for renewable energy. Dimitris' interests include mainly two types of polymer-based soft materials that combine these two elements: polyelectrolyte self-assembly and nanocomposite materials. In the first example, complex coacervation (i.e. a liquid-liquid phase separation phenomenon), is used as a platform for soft material design. Using polypeptides as a model system, many aspects of complex coacervation (e.g thermodynamics of coacervate formation, parameters that affect complexation, rheological and interfacial properties of coacervates) can be studied. More complex molecular design can be utilized wherein polyelectrolyte domains are connected to neutral polymer blocks. Mixing of polyelectrolyte block-copolymers with oppositely charged homo or block-copolymers can result in the formation of nanometer-sized micelles or hydrogels with coacervate core domains. In the second example, his attention is focused on polymer/carbon nanotube (CNT) or other carbon allotropes (e.g. graphene) nanocomposite materials. He is interested in polymer functionalization of CNTs that help circumvent the inherent insolubility of CNTs, and considerably widen the scope of nanocomposite materials that can be produced. Dimitris' strategy involves attachment of substituted polymerization initiators onto a CNT surface (e.g. covalent attachment of benzocyclobutenes onto CNTs using a Diels-Alder [4 + 2] cycloaddition reaction). With a judicious choice of substitution, initiators of most popular polymerization techniques can be attached. Complete control over the grafting percentage of initiator and surface-initiated polymerizations allows for the synthesis of nanocomposite materials with desired compositions, an essential for any application. The resulting nanocomposite materials exhibit improved mechanical and thermal properties, compared to pure polymers.