Research areas include controlling the orientation and long-range lateral ordering of block copolymers and the use of block copolymers to fabricate nanostructured materials. Interests include the surface and interfacial properties of polymers, phase transitions in polymers, directed self-assembly processes, the statics and dynamics of interfacial assemblies of nanoparticles, the jamming of nanoparticles assemblies to structure fluids and the response of the assemblies to external stimuli, the influence of supercritical fluids on phase transitions, dynamics in polymer thin films, the wrinkling, crumpling and folding behavior of thin polymer films, and polymer-based photovoltaic materials.
Pushing the limits of BCP nanotechnology to two extreme limits, the utra-small on the single nanometer level for element size,, where he has developed routes to generate patterns with a full pitch of 5 nm, and to the very large, to the hundreds of nanometer level using brush block copolymers, which is finding application as 1D and 3D photonic bandgap materials. In addition, quantitatively describing both solvent- and thermal-annealing routes to enhance long-range lateral ordering of the nanodomains of BCPs in terms of fundamental thermodynamic parameters and the dynamics of the BCP chains.
Using functionalized nanoparticles in one fluid phase, and complementary end-functionalized polymers in the second fluid, the interactions of the polymers and functionalized polymers at the interface lead to the formation of a nanoparticle surfactants comprised of nanoparticle heads to which multiple polymer chains are associated. These systems self-regulates the number of chains that can attach to the nanoparticles through a minimization of the interfacial energy per nanoparticle. This, in turn, increased the forces holding the nanoparticles at the interface. When the fluids phase are deformed by external fields, like shear, magnetic or electric fields, the interfacial area is increased, more nanoparticle surfactants form at the interface and, when the field is removed, the nanoparticle surfactants jam and the liquids are trapped in highly non-equilibrium shapes. The fluids are structured, producing and entirely new concept in the design of materials. Here the components are completely fluid, but the domains are structured. This revolutionary concept in materials design has the potential to lead through breakthrough technologies that rely on the dynamics of the liquid components but the structuring introduced by the interfacial jamming of nanoparticle. Such materials have intriguing possible application in the design of all-liquid batteries, high resolution separations media and to ultra-low friction coefficient materials.
B. S., Chemistry, 1976, Boston State College
M. S., Polymer Science and Engineering, 1976, University of Massachusetts at Amherst
Ph. D., Polymer Science and Engineering, 1979, University of Massachusetts at Amherst