Session: POLY/PMSE Poster Session:

Precise control of branching in synthetic polymers represents an essential tool for manipulating material properties. Of the branched polymer structures that can be readily synthesized, a graft molecular architecture is one of the simplest to produce yet offers a rich design space through the control of grafting density, side-chain molecular weight, and backbone molecular weight. The ability to precisely tune these parameters has attracted much interest in the polymer synthesis community in recent years. The work reported here expands on the current understandings of a graft-through synthetic approach. Specifically, we investigate how the chemical structure and initial feedstock composition in Ring Opening Metathesis Polymerization (ROMP) affects the copolymerization kinetics of a macromonomer and small molecule comonomer and, therefore, the statistical distribution of side-chains along a polymer backbone. To characterize the copolymerization kinetics, terminal and non-terminal models were applied to monomer conversion data collected via nuclear magnetic resonance spectroscopy. Our findings point to a complex correlation between macromonomer molecular weight, monomer chemistry, and the initial feedstock composition, regarding the effects that these parameters have on the statistical distribution of side chains along a graft polymer backbone. These findings elucidate fundamental design principles that must be considered when using a graft-through copolymerization.

<b>Figure.</b> Macromonomer reactivity ratios as a function of molecular weight and initial feedstock composition (i.e., grafting density). Results shown are from non-terminal model fits.

Figure. Macromonomer reactivity ratios as a function of molecular weight and initial feedstock composition (i.e., grafting density). Results shown are from non-terminal model fits.

Marc Hillmyer

University of Minnesota Twin Cities

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