IRG 2

Novel Processing Methods for Nanostructured Polymer Blends, Composites and Supramolecular Structures

Kenneth R. Shull (Leader), materials science & engineering
L. Catherine Brinson, mechanical engineering
Linda J. Broadbelt, chemical & biological engineering
Bartosz Andrzej von Poray Grzybowski, chemical and biological engineering
SonBinh T. Nguyen, chemistry
Monica Olvera de la Cruz, materials science & engineering
Samuel I. Stupp, materials science & engineering
John M. Torkelson, chemical & biological engineering

The goal of IRG2 is to understand the factors controlling the structure, mechanical and dynamic responses of hierarchically-structured materials based on polymers and nanoparticles. The interrelated sub-themes of this work are listed below.

Dynamics of confined polymer systems
The glass transition of an amorphous polymer is a measure of local chain dynamics that is affected by the proximity to an vapor, solid, or liquid interface. Fluorescence methods developed in IRG2 are providing a greatly enhanced understanding of the length scales over which these interfaces affect the glass transition dynamics, and of the way these dynamics are affected by the details of the interfacial interactions.

The role of sequence distribution in copolymer assembly
Recent advances in polymerization chemistry provide an opportunity to tailor monomer sequence distributions in copolymers in ways that were not possible only a few years ago. IRG2 is investigating the role that the sequence distribution has on the assembly of non-blocky copolymers in melts and solutions. Gels based on more traditional block copolymers are also being used to understand the origins of fracture toughness in soft, highly extensible solids.

Interfacial assembly
Copolymer assembly at the interface between both miscible and immiscible liquids is being investigated by IRG2. Molecules used in these studies include peptide amphiphiles, which have self-assembly characteristics that depend on the detailed sequence of peptides in the relatively low molecular weight amphiphilic molecules. Interfacial co-assembly of peptide amphiphiles with high molecular weight polymers is being used to develop two-dimensional membranes for biomedical applications. The structure, mechanical response, and transport properties of these materials depend on a combination of thermodynamic and kinetic factors that are being elucidated by IRG2.

Nanoparticle-based materials
Responsive nanoparticles designed to interact with one another in controlled ways are being investigated as platforms for materials development. Recent examples include the development of nanoparticle-based methods for producing robust, three-dimensional metal structures with nanoscale pore sizes. In another example, photoresponsive nanoparticles have been designed and fabricated into rewritable, self-erasing paper.

Scanning electron microscopy image of the new polymer gel/carbon nanotube composite. More>

Selected Research Highlights:

A Reliable Strategy for Designing Functional Polymer Nanoparticles Using Ring-Opening Metathesis Polymerization

Jun-Hyun Kim and SonBinh T. Nguyen

More>

Mystery of Charge Asymmetry: Anionic Macroions in Periodic Lattices Held by Hydrated Cations and Not Vice-versa

William Kung, Dongsheng Zhang, Pedro Gonzales-Mozuelos, Monica Olvera de la Cruz

More>

1-Dimensional Nanopatterned Polymers for Future Use in Microelectronics

Manish K. Mundra, Suresh K. Donthu, Vinayak P. Dravid, and John M. Torkelson

More>

Electrostatic Attraction Between Cationic-Anionic Assemblies with Surface Compositional Heterogeneities

Y. S. Velichko and M. Olvera de la Cruz

More>