# Presentation: 359447

## CAREER: Development of Novel Ternary Copolymer AssembliesRobert B. Grubbs, Dartmouth College, DMR 0239697

- Linking chemically dissimilar polymer chains together into block copolymers generally leads to materials with nanometer-sized structures.
- We are attempting to use this behavior to locate multiple nanometer-scale metallic particles in polymer films. Alkyne-functional block copolymers have proven to effective for the localization of cobalt-functional polymer blocks to defined regions of a polymer film. Organization of cobalt-containing domains might allow the preparation of high capacity magnetic storage devices and materials with novel photonic and electromagnetic properties could result from organization of other metal particles.1
- We have examined systems resulting from reaction of alkyne-functional polymers and copolymers with cobalt clusters as precursors to cobalt nanoparticles. Copolymers with water-soluble poly(ethylene oxide (PEO) blocks lead to cobalt particles that form necklace-like structures (Figure 1a). Heating of gold nanoparticles with cobalt-functionalized polymer ligands leads to bimetallic particles (Figure 1b).

- We have also developed effective routes to prepare these polymers by coupling small molecules to polymer precursors (Scheme 1)*.**2** *We are currently investigating the self-assembly of these materials and their magnetic properties.

**2 hours, 110 °C**

**Figure 1.** Transmission electron micrographs of (*a*) cobalt nanoparticles resulting from the heating of cobalt carbonyl-modified copolymers of PEO and alkyne-functional monomers and (*b*) cobalt carbonyl/alkyne-functional block copolymer-coated gold nanoparticles (cobalt-rich regions appear dark and gold nanoparticles appear darker).

- 1. Grubbs, R. B. *J. Polym. Sci., Part A: Polym. Chem.* **2005**, *43*, 4323-4336. (DOI: 10.1002/pola.20946)
- 2. Sessions, L. B.; Cohen, B. R.; Grubbs, R. B. *Macromolecules* **2007**,* 40*, 1926-1933. (DOI: 10.1021/ma0625915)

## CAREER: Development of Novel Ternary Copolymer AssembliesRobert B. Grubbs, Dartmouth College, DMR 0239697

-   Five Ph.D. students, Laura Sessions (Ph.D., 2006), Yu Cai (6th year), Anna Greene (2nd year), and Addison Bouchard (2nd year); one post-doc, Dr. Anand Sundararaman; one M.S. student, Qing Xia (M.S., 2006); two undergraduates, Kristen Limbach (’08) and Jeff Garber (’09); and one high school student, Natasha Kozliouk, are currently involved in this research.
-   Jesse McCann (now a Chemistry Ph.D. candidate at U. Washington), Kjell Ericson, Jakub Wegrzyn (MS, Chemical Engineering Practice, MIT 2006), Benjamin Cohen (Johns Hopkins Medical School), and Gloria Sheng (MS program in Nano- and Microtechnology Enterprise, Cambridge; entering graduate school at Caltech in Fall 2007) prepared Honors Theses based upon their work in the lab as undergraduates at Dartmouth.
-   Lindsey Saunders (Brandeis University), Ellen Robertson (Kalamazoo College), Ben Stokes (U. Wisconsin), Andy Wills (Carleton College), and Analiz Rodriguez (New College, FL) have participated in aspects of this research through the Dartmouth NSF-REU program in Molecular Materials.
-   A recent group photograph (9/2006) appears to the right.  From the left, Qing Xia, Anna Greene, Laura Sessions, Anand Sundararaman, Addison Bouchard Yu Cai, and Barney Grubbs are pictured.

** **
- A graduate/upper-level undergraduate course in synthetic polymer chemistry (Chemistry 109) was offered in the fall of 2005 and the spring of 2007.
- An informal biannual meeting, the New England Polymer Chemistry Workshop, has been developed in collaboration with researchers in the greater geographical area.  These workshops have provided professors, post-docs, graduate students, and undergraduates  with regular opportunities to discuss their research with others and is leading to the development of collaborations across institutional lines.

- CAREER: Development of Novel Ternary Copolymer AssembliesRobert B. Grubbs, Dartmouth College, DMR 0239697