AMADEus Seminar - Prof. James J Watkins, Friday 28 September 2012 - 3:00 pm - Location: ENSCBP, Amphi 3
Polymer Science and Engineering Department and
Center for Hierarchical Manufacturing
University of Massachusetts, Amherst, MA USA 01003.
"Additive-Driven Self-Assembly of Hybrid Materials and Devices"
The preparation of well ordered, hybrid polymer/inorganic nanostructures with exceptional control over size, shape, composition, organization and/or dispersion of nanoscale domains is central to the development of next-generation materials and devices for energy generation and storage, structural composites, microelectronics, communications, and other applications. While the desired structures can often be identified, their realization via practical fabrication methods has remained challenging, especially for those cases that require high concentrations of nanoparticles (NPs) or other functional additives within ordered periodic structures.
We find that microphase separation in block copolymer templates can be enhanced by homopolymer, organic, or nanoparticle additives that undergo multi-point hydrogen bonding with one of the segments of the polymer template to yield well-ordered materials with tunable periods between 3 and 30 nm. These interactions can also be used to enhance dispersion and stability of additives in homopolymer or non-microphase separated copolymer systems. The additives, which can include metal and semiconducting nanoparticles, fullerenes, functional organics or dyes can impart functionality to the material or device. The strong interactions enable particle loadings of more than 40% in the target phase, resolving a crucial constraint for many applications and also serve to suppress additive aggregation, yielding stable morphologies. Block copolymer templates can in turn be designed to serve as an active component in a device, such as a charge or ion transport media, or serve as an intermediate precursor to a desired structure. By varying the number and nature of functional groups of the additive we study how the strength and density of interactions influence compatibility and the morphology and segregation strength of the composite. We have used this additive-driven assembly approach to fabricate polymer-based battery electrolytes, photovoltaics, floating gate field effect transistor memory devices and other functional materials and structures.
Ultimately transfer of laboratory advances to practice requires the development of tools and processes that enable cost-effective and reliable manufacturing. The NSF Center for Hierarchical Manufacturing (CHM) at University of Massachusetts Amherst is developing materials and processing approaches to enable the fabrication of nanotechnology enabled devices on a roll-to-roll (R2R) platform using self-assembly, nanoimprint lithography and other techniques. The use of these platforms for device fabrication of flexible substrates will be discussed.
Prof. James J Watkins Research Interests:
Macromolecular templates for functional device structures, materials synthesis and processing in supercritical fluids, phase behavior and transport in multi-component polymer systems, scalable fabrication of nanostructure materials.
Honors and Distinctions:
- Camille Dreyfus Teacher-Scholar Award (2000-2005)
- David and Lucile Packard Foundation Fellowship for Science and Engineering (1998-2003)
- CAREER Award, National Science Foundation (1998-2002)
- 3M Non-tenured Faculty Award (1998 - 2000)
- Unilever Award, American Chemical Society for Outstanding Graduate Research in Polymer Science and Engineering (1998)
- Arthur K. Doolittle Award, Division of Polymeric Materials Science and Engineering, American Chemical Society (1996)