1. Bipyridine Functionalized Polymers
Mallory McVannel, Shannon Harris, Conner Graham, M. Lee Pippin, Juan V. A. Requena, Alexander D. Schwab
A. R. Smith Department of Chemistry

2. Abstract
We are interested in investigating the preparation of Metal Coordination Polymer Networks (MCPN) by attaching 4’-Methyl-2, 2’-bipyridine-4-carboxylic acid (MCPBY), a ligand for the complexation of metals, to a variety of polymers. MCPBY was reacted with a low molecular weight (Mn: 2,500 g/mol) and a high molecular weight (Mn: 27,000 g/mol) bis-(3-aminopropyl) terminated poly (dimethylsiloxane) (PDMS), a bis (hydroxyalkyl) terminated poly (dimethylsiloxane) (Mn: 5,600 g/mol) and a bis(3-aminopropyl) terminated poly(ethyleneoxide) (Mn: 1,500 g/mol) in order to form the bipyridine terminated polymer product. The resulting products were characterized using 1H NMR and GPC.

3. Introduction
Both thermoplastics and thermosets (e.g. typical rubbers) are composed of polymer molecules
Thermoplastics
Thermosets (rubbers)
Long, unconnected polymer chains, recyclable
polymer network, long- chain molecules connected by cross-links, unrecyclable

4. Metal Coordination Cross-links
Our overall goal is to synthesize a rubber that would maintain its desirable physical properties and yet be recyclable.
Replace conventional covalent cross-links with non-permanent, metal coordination complexes.
New properties are also unlocked with metal coordination cross-links
DRAW MOLECULE CROSS LINK PRODUCT (FOUND ON POSTER BOARD)

5. Our Synthetic Approach
Begin with linear polymer molecules
Attach metal binding ligands to the ends of the polymer molecules
Introduce metal cations for metal coordination to form a polymer network + 2

6. Polymer Modification Scheme
The work presented here deals primarily with the attachment of a metal binding ligand (bipyridine) to various polymer molecules
Amine (NH2) terminated polymer
4-methyl-2,2’-bipyridine-4’-carboxylic acid (mcbpy)
Bipyridine (bpy) terminated polymer
Carbodiimide coupling reagents were also used
N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDCI)
N,N’-dicyclohexylcarbodiimide (DCC)

7. Polymer Starting Materials
NH2 terminated poly(dimethylsiloxane) (NH2PDMSx, x = 2500 or 27000)
Two molecular weights used: 2,500 & 27,000 g/mol
NH2 terminated poly(ethyleneoxide) (NH2PEO1500) 1500 g/mol
OH terminated PDMS (OHPDMS5600) 5600 g/mol

8. bpyPDMS2500 1H NMR Results
NH2PDMS2500 was reacted with mcbpy in methylene chloride with EDCI for 48 hours
bpyPDMS
NH2PDMS

9. bpyPDMS 2500 GPC Results GPC separates molecules based on their size
ELSD detects all polymer
UV/vis measures light absorbance at 295 nm
Sensitive to bipyridine
Relative peak positions indicate successful bipyridine attachment

10. bpyPDMS H NMR Results
NH2PDMS was reacted with mcbpy in methylene chloride with EDCI for 48 hours
NH2PDMS
bpyPDMS

11. bpyPDMS27000 GPC Results
Fewer endgroups relative to PDMS2500 makes 1H NMR and GPC analysis more challenging.
NH2PDMS appears to have a significant low MW component
UV-vis indicates bpy attached to PDMS

12. Fractionated NH2PDMS27000
To eliminate low MW component, fractionation with toluene/methanol was attempted
Relative amount of low MW component is reduced by fractionation
Further investigation necessary

13. bpyPEO1500
NH2PEO1500 was reacted with mcbpy and DCC in N,N- dimethylformamide for 48 hours
NH2PEO
bpyPEO

14. bpyPDMS5600
OHPDMS5600 was reacted with mcbpy and EDCI in methylene chloride for 48 hours
1H NMR analysis indicated that bpy attachment was unsuccessful
Carbodiimide coupling reagents can produce esters, though an acid catalyst is often required
In future attempts small quantities of an organic acid will be included.

15. Future Work
Fractionation of the NH2PDMS27000 starting material will be improved
NH2PEO1500 synthesis will be further refined to increase yield and reduce impurities
Carbodiimide use in ester formation will be further investigated
Bpy terminated polymers will be mixed with ruthenium(II) complexes, cast into films, and studied with UV/vis, DSC, and oscillating shear rheometry
Solvent annealing might be necessary to promote cross-linking

16. Acknowledgements We thank the following organization for funding:
Pfizer, Inc.
NC Biotechnology Center
The ACS Petroleum Research Fund
NSF supported ACREE Program
ASU Office of Student Research
ASU
Other undergraduates contributing to this project
M. Ryan Kincer, Ben Deming, Ben Gray, Sarah Miller, Scott Meadows, Kurtis Price

17. References
McCafferty, D. G.; Bishop, B. M.; Wall, C. G.; Hughes, S. G.; Mecklenbert, S. L.; Meyer, T. J.; Erickson, B. W. Tetrahedron 1995, 51,
Mcbpy synthesis
Montalbetti, C. A. G. N.; Falque, V., Tetrahedron 2005, 61,
Carbodiimide coupling reagents for amide and ester bond formation
Canard, G.; Piguet, C. Inorganic Chemistry 2007, 46,
Ruthenium(II) precursor complexes for cross-linking
Smith, A. P. Fraser, C. L. Macromolecules 2003, 36,
Ruthenium(II) bpy complex syntheses for cross-linking