Quasiliving cationic ring-opening polymerization of 2-ethyl-2-oxazoline in benzotrifluoride, as an alternative reaction medium

Cationic ring-opening polymerization (CROP) of 2-ethyl-2-oxazoline (EtOx) was systematically investigated in benzotrifluoride (BTF), which is considered as an environmentally less harmful solvent than many conventional reaction media. Simultaneously, polymerizations in conventional solvents, such as acetonitrile, N,N-dimethylacetamide and toluene, were also carried out for comparison in the 80-100 degrees C temperature range. Kinetic experiments revealed that the monomer consumption occurs by first order kinetics and the number average molecular weights linearly increase in line with the theoretical molecular weight as a function of monomer conversion. These findings indicate that the polymerization takes place by quasiliving CROP in all the investigated solvents, including BTF as well, resulting in PEtOx with prederminded molecular weights and polydispersities of 1.3-15. The highest polymerization rates were obtained in BTF, resulting in high conversions in short reaction times at 100 degrees C reaction temperature. The Arrhenius parameters of the polymerization of EtOx in BTF indicates relatively high activation energy in comparison with other applied solvents, however, a compensation effect between the activation energies and frequency factor is observed for such polymerization in a variety of solvents. Our findings are expected to enable the convenient synthesis of polyoxazolines and polyoxazoline-based well-defined polymer architectures in BTF, an environmentally advantageous alternative solvent to harmful polymerization media, with high polymerization rates in short reaction times without the need for any special conditions or equipment.

Automated summary

Cationic ring-opening polymerization of EtOx in BTF and other solvents shows similar kinetics, with BTF offering the highest polymerization rates and conversions; The Arrhenius parameters indicate relatively high activation energy in BTF, but a compensation effect is observed between activation energies and frequency factors in various solvents.