Current Position: Research Scientist, Carbon

B.S.E. Research:

Ring-opening metathesis polymerization (ROMP), a type of living polymerization, is used to synthesize polymers with tunable molecular weights with narrow molecular weight distributions. However, living polymerizations form one polymer chain per molecule of initiator used in the reaction—a disadvantage when the initiator is costly and the reaction is taken to low conversions. Chain transfer agents (CTAs) are economical for synthesizing low molecular weight chains because they generate multiple polymer chains per molecule of CTA. In addition, CTAs containing the desired end group can be used for synthesizing macromers, polymer chains with one functional end group. These macromers may be precursors to copolymers since the functional group can participate in a further reaction. As such, CTAs prove to be useful for ROMP, given that the chain transfer event is regioselective to yield one major product.

The project aims to investigate the activity of epoxide- and D3-based CTAs on the ROMP of cyclopentene. Each CTA is assessed for its chain transfer coefficient and degree of regioselectivity for the polymerization. The chain transfer coefficients (CT ) are calculated using the chain transfer equation previously verified by the group. Gel permeation chromatography (GPC) is used to obtain Mw and Đ, and therefore Mn, of the polymer product, which are used to calculate the value of CT . Proton nuclear magnetic resonance (1H NMR) is used to verify a 50:50 distribution of initiator end-group and CTA end-group functionality, and matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) reveals molecular weights of the individual chains. Analyzing data from these two techniques provides information about the regioselectivity of the chain transfer events.

Depending on the regioselectivity of the chain transfer events, the CTA may be used in synthesizing polycyclopentene (PCP) macromer chains with the specified end group. PCP macromonomers with epoxide end-functional groups may be precursors to polyethylene oxide-type (PEO) comb polymers. In its unsaturated form, the product may also be used as a rubber toughening agent for epoxies. PCP macromers with D3 end-functional groups may be used to synthesize polydimethylsiloxane-type (PDMS) comb polymers.