Mark J. Pender
Current Position: Senior Research Scientist, Michelin Corporation
Doctoral Institution: University of Pennsylvania
Princeton Postdoctoral Research:
Much of my Ph.D. work in Chemistry centered around the transition metal catalyzed synthesis of new monomers and polymers as precursors to boron carbide-based ceramics. In that case, there was a lacking of suitable monomers, and subsequently, polymers that could fulfill this role.
Now as I begin to expand my knowledge of polymer science, I have found a lacking of readily available monomers for ring opening metathesis polymerization (ROMP). ROMP relies on strained-ring systems and the handful of commercially available monomers give rise to polymers with a narrow range of properties. My goal is to develop a readily accessible library of monomers based on the functionalization of a common substrate. The platinum catalyzed hydrsilylation of vinylnorbornene gives rise to norbornene derivatives that are as varied as the commercially available silanes used in the reactions. The hydrosilylations are simple, one-pot reactions that are amenable to a wide range of functionalities and which allow one to avoid many of the problems associated with the organic/synthetic methodology used to synthesize similar norbornene derivatives. Thereby, one can readily incorporate a wide range of functionality into ROMP based polymers with little effort or deviation in synthesis and produce ROMP polymers with previously unobserved, but targeted properties.
Additionally, I am intrigued by the microphase separation of block copolymers. The excellent work demonstrated previously in this group has established that thin films of the appropriate block copolymers can give rise to lithographic masks that produce lines or dots. My goal is to use the microphase separated copolymers as a template for the growth of nanostructures.
For a particular block copolymer thin film on a silicon substrate, one of the blocks can be selectively removed to reveal the native oxide layer of the substrate. This step gives rise to a polymer film with troughs or holes. With an appropriate silane (eg. RSi(OR')3), one can then selectively functionalize the surface only where these troughs exist. If R is a thiol, one can then attach gold particles to the surface. By repeated exposure to cross-linking thiols and gold nanoparticles, one can effectively build up gold nanowires within the troughs.
Work is also being initiated in the synthesis of well-controlled block copolymers by living-radical polymerizations. I am also investigating the microphase separation of block copolymers within confined volumes with a cross-sectional diameter ~10x the scale of the microstructures. Such confinement will hopefully give rise to unique ordering of microstructures.