Tirrell Group

Dimitris Priftis, Ph.D.

Dimitris Priftis received a BSc in chemistry from the Aristotle University of Thessaloniki in 2004. He then moved to the University of Athens where he obtained a MSc (2006) and a PhD (2009) in polymer chemistry for his work on polymer functionalization of carbon nanotubes under the supervision of Professor Nikos Hadjichristidis. In 2010 he joined Professor Matthew Tirrell’s group as a postdoctoral researcher at the University of California, Berkeley. There he worked on the phase behavior (complex coacervation) of polyelectrolyte complexes. Currently he is at the Pritzker School of Molecular Engineering where he is continuing his work on polyelectrolyte self-assembled materials in Professor Tirrell’s group. His research interests include the design, development, and study of the behavior (in solution and bulk) of novel polymer-based soft materials through the intelligent use of processes such as self-assembly, combined with the ability to manipulate the chemical structure of polymers.

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.

Self-Assembly of α-Helical Polypeptides Driven by Complex Coacervation

D. Priftis, L. Leon, Z.Y. Song, S.L. Perry, K.O. Margossian, A. Tropnikova, J.J. Cheng and M. Tirrell. Self-Assembly of α-Helical Polypeptides Driven by Complex Coacervation. Angewandte Chemie Intl Edition. 2015. Vol. 54, Pg. 11128-11132.

Chirality-selected phase behaviour in ionic polypeptide complexes

Perry, Sarah L., et al. "Chirality-selected phase behaviour in ionic polypeptide complexes." Nature communications 6 (2015): 6052.

A molecular view of the role of chirality in charge-driven polypeptide complexation

Hoffmann, K. Q., et al. "A molecular view of the role of chirality in charge-driven polypeptide complexation." Soft Matter 11.8 (2015): 1525-1538.

Interfacial Tension of Polyelectrolyte Complex Coacervate Phases

J. Qin, D. Priftis, R. Farina, S. L. Perry, L. Leon, J. Whitmer, K. Hoffmann, M. Tirrell, and J. J. de Pablo . Interfacial Tension of Polyelectrolyte Complex Coacervate Phases. ACS Macro Letters. 2014. Vol. 3, Pg. 565-568.