Binary Copolymerization by Ring-Opening Metathesis Polymerization of Norbornene-Type/Cyclooctene-Type Macromonomers

The development of polymerization mechanisms brings both opportunities and challenges to research on copolymerization. The breakthrough in radical polymerization, anionic polymerization, and ring-opening metathesis polymerization has made it possible to realize copolymerization of macromonomers with their molar mass ranging from 103 Da to 105 Da. Different from the copolymerization of small-molecule monomers, the copolymerization of macromonomers is influenced by the size of the monomer and the topology of the chain segment linked to the living polymerization center. To investigate the copolymerization between macromonomers, macromonomers of different molar mass, polymerizable terminal functional group, side chain, and target degree of polymerization (DP) are copolymerized and studied. Well-established copolymerization models include the nonterminal model using the Beckingham–Sanoja–Lynd (BSL) method and the terminal model using the Meyer–Lowry method. Besides, a binary copolymerization model established on the kinetic difference between homopolymerization and copolymerization was also used for kinetic analysis. This method allowed us to quantify the influence caused by the addition of another macromonomer during the copolymerization process through the calculation of the hybrid constants, which could be converted to reactivity ratios directly, affording a helpful complement to the nonterminal model and terminal model. The analysis over polymerization kinetics suggested that the presence of macromonomers with higher molar mass could hinder the polymerization of macromonomers with lower molar mass by affecting the topology of the chain segment linked to the living polymerization center of the polymerization and vice versa. This suggested that the copolymerization of macromonomers could be tuned by feeding ratios of macromonomers with different molar masses. In summary, our research demonstrates the use of several copolymerization models to study the copolymerization of different macromonomers. We believe that this work provides a comprehensive study of the kinetics and mechanisms of macromonomer copolymerization and affords a distinct but effective model for the study of copolymerization.