Hydrogen atom transfer (HAT) mediators are useful for radical chemistry in chemical synthesis. HAT is involved in the termination step of radical reactions between hydrogen atom and carbon-centered radical. This work focused on the kinetic aspects of the Lewis base-catalyzed, complexation-induced hydrogen atom transfer (LBCI-HAT) polymerization by evaluating the following key factors: (1) the extent of para-substituted styrene bearing electron-withdrawing and electron-donating groups, the coordinating agents effects, and (3) ligand effects in the presence of LB. The FT-NIR allows the time-resolved measurement of monomer conversion in radical polymerization to study polymerization reaction kinetics. The coordinating agent, 18-crown-6-ether, has a significant influence on the polymerization rate. The value of –dln[M]/dt obtained by linear fitting of the first-order kinetic plots of the monomer conversion was 11×10–2 s–1 for the presence of 18-crown-6-ether. In addition, the polymerization rate of styrene without a substituent showed four times faster than that of the EDG-substituted styrene (St-OMe). Moreover, we elucidated the LBCI-HAT-radical polymerization pathways and structure-reactivity correlation in LBCI-HAT. The LBCI-HAT-radical polymerization offers the scope of controlled polymer architectures in open air.

Sustainable controlled radical polymerization of para-substituted styrene by alkali metal lewis-base hydrogen atom transfer catalyst

ACS Fall 2021

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