Macromolecules, Vol.52, No.15, 5707-5721, 2019
One-Pot Synthesis of Hyperbranched and Star Polyketones by Palladium-Catalyzed Terpolymerization of 4-tert-Butylstyrene, Divinylbenzene, and Carbon Monoxide
We demonstrate in this article the first synthesis of a class of hyperbranched and star polyketones. by Pd-catalyzed terpolymerization of 4-tertbutylstyrene (TBS), divinylbenzene (DVB), and carbon monoxide (CO), where TBS/DVB undergoes alternating copolymerization with CO. Hyperbranched polyketones are first synthesized by direct one-pot terpolymerization, where difunctional DVB monomer serves as the branching agent. A simple variation of the feed ratio of TBS and DVB facilitates the efficient tuning of the branching density in the hyperbranched polymers. The success of the terpolymerization enables the subsequent one-pot synthesis of star polyketones by both "core-first" and "arm-first" strategies. In the "core-first" strategy, multinuclear Pd-containing hyperbranched cross-linked polyketone cores are first formed by TBS/DVB/CO terpolymerization and serve as multifunctional initiating cores for subsequent multidirectional arm growth upon TBS addition. In the "arm-first" strategy, "living" TBS/CO alternating copolymerization is first carried out to grow linear polyketone arms, followed by the addition of DVB for star formation by cross-linking the linear arms. Tuning the polymerization parameters in both strategies allows the efficient design of star polyketones of varying arm lengths and average arm numbers.