The research in the Adamson group at UConn includes two broad topics: polymer synthesis / self-assembly and two-dimensional materials. The graduate students in our group are either enrolled in the Chemistry Department or the Polymer Program of the Institute of Materials Science. This gives us a very diverse group with interests and expertise ranging from materials science to chemical synthesis.
Polymer synthesis and self-assembly starts with the synthesis of polymers, often block copolymers, by methods such as high vacuum living anionic polymerization, ring opening metathesis polymerization (ROMP) and controlled radical methods such as ATRP. Self-assembly of these polymers is driven by the immiscibility of the blocks in polymer melt, or by the difference in solubility of the polymer blocks in a solvent.
The growth of polymer brushes is an active area of our research, and we have recently developed a “grafting-through” approach to growing surface initiated polymer brushes. This approach provides monomer to the growing polymer chains by diffusing it through the surface from which the chains are growing. This mechanism reverses the normal monomer concentration gradient, meaning that the growing ends of the short chains near the surface see a higher concentration of monomer than do the longer chains. The result is a more uniform and dense brush than is possible using traditional “grafting-from” or “grafting-to” approaches.
Research interest in graphene materials has increased at an exponential rate since the demonstration of mechanically exfoliated sheets of graphene in 2004. Our group has developed and introduced several new approaches to pristine graphene exfoliation, and we are actively pursuing the use of graphene as a two-dimensional surfactant. Based on our interfacial trapping technique, we are able to form graphene stabilized emulsions, and by polymerizing the continuous oil phase, create inexpensive, low density, and electrically conductive composite materials. These materials are cheaper to make than polystyrene foam, and represent a new approach to graphene based porous electrodes. In addition, by the appropriate choice of monomer, we are able to make flexible foams that change electrical resistance with deformation.
Our research interest in hexagonal boron nitride (BN) includes both functionalization and composites. Hexagonal boron nitride is the isoelectric analogue of graphite, and like graphite, can behave as a two-dimensional surfactant. Unlike graphite, however, it is an electrical insulator, but is an excellent thermal conductor. We are focusing composite materials based on the polymerization of the continuous phase of BN stabilized emulsions. Several polymer systems are being investigated with potential applications including thermally conductive but electrically insulating composites and flame retardant materials with very low loadings of BN.
Although we are interested in the use of pristine (never oxidized) graphite as a 2D surfactant, we are also interested in the more commonly used graphene oxide (GO). In particular, we are interested in the characterization of GO and its fractionation into more well-defined materials. Using fractionation based on the degree of oxidation of the sheets, we are able to quantify the dispersity of the oxidation in a GO sample. In addition, by using fractions with different degrees of oxidation, we are able to make composite materials with different properties.