Effect of the Catalytic System and Polymerization Time on the Characteristics of Poly(oegma) and Poly(cbma) Synthesized by Atrp

In this study, optimal conditions for atom-transfer radical polymerization (ATRP) of oligo(ethylene glycol) methacrylate (OEGMA) and carboxybetaine methacrylate (CBMA) monomers were developed using initiators with different functionalities to obtain functional hydrophilic polymers that are promising for bioengineering and modification of proteins, DNA, RNA and other biological macromolecules. The study focuses on the influence of the ligand type, initiating system, and polymerization duration on the process kinetics, molecular weight characteristics, and hydrodynamic size of the resulting polymers. 2,2'-bipyridine was used as a ligand for OEGMA polymerization. Under similar conditions, the use of 2,2'-bipyridine for CBMA did not result in polymer formation, indicating differences in the reactivity of the monomers and their interaction with the catalytic system. For the polymerization of CBMA, 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETА) was used as an alternative ligand. In the presence of HMTET, CBMA polymerization proceeded significantly faster but was accompanied by higher dispersion of the resulting polymers, indicating a lower degree of process control. The effects of polymerization duration and initiator functionality on the degree of polymerization, molecular weight, dispersion (Đ), and hydrodynamic diameter (Dh) were studied for both monomers. It was found that for OEGMA, increasing the reaction duration ensures a consistent increase in molecular weight and hydrodynamic diameter while maintaining a relatively narrow molecular weight distribution, whereas for CBMA, the main molecular weight characteristics are formed already in the early stages of polymerization. The obtained patterns are important for the development of reproducible polymer platforms for bioengineering, as controlled length and architecture of polymer chains are crucial parameters in the creation of protein–polymer conjugates using ATRP. Poly(OEGMA), containing oligoethylene glycol fragments, and poly(CBMA), a zwitterionic polymer, represent promising materials for modifying proteins, regulating their stability and functional properties, and for potential use in drug delivery and biomedical technologies. Thus, the obtained results highlight the need to select the catalytic system, ligand, initiator functionality, and reaction duration taking into account the chemical nature of the monomer to obtain polymers with controlled characteristics suitable for further use in bioengineering systems.