Conformational Parameters and Hydrodynamic Behavior of Poly(2-Methyl-2-Oxazoline) in a Broad Molar Mass Range

Alexander S Gubarev; Alexey A Lezov; Anna N Podsevalnikova; Nina G Mikusheva; Petr A Fetin; Ivan M Zorin; Vladimir O Aseyev; Ondrej Sedlacek; Richard Hoogenboom; Nikolai V Tsvetkov

doi:10.3390/polym15030623

Conformational Parameters and Hydrodynamic Behavior of Poly(2-Methyl-2-Oxazoline) in a Broad Molar Mass Range

Polymers (Basel). 2023 Jan 25;15(3):623. doi: 10.3390/polym15030623.

Affiliations

¹ Department of Molecular Biophysics and Polymer Physics, Saint-Petersburg State University, Universitetskaya Nab. 7/9, 199034 Saint-Petersburg, Russia.
² Institute of Chemistry, Saint-Petersburg State University, Universitetskaya Nab. 7/9, 199034 Saint-Petersburg, Russia.
³ Department of Chemistry, University of Helsinki, Helsinki, P.O. Box 55, 00014 Helsinki, Finland.
⁴ Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium.

Abstract

In this work, we report our results on the hydrodynamic behavior of poly(2-methyl-2-oxazoline) (PMeOx). PMeOx is gaining significant attention for use as hydrophilic polymer in pharmaceutical carriers as an alternative for the commonly used poly(ethylene glycol) (PEG), for which antibodies are found in a significant fraction of the human population. The main focus of the current study is to determine the hydrodynamic characteristics of PMeOx under physiological conditions, which serves as basis for better understanding of the use of PMeOx in pharmaceutical applications. This goal was achieved by studying PMeOx solutions in phosphate-buffered saline (PBS) as a solvent at 37 °C. This study was performed based on two series of PMeOx samples; one series is synthesized by conventional living cationic ring-opening polymerization, which is limited by the maximum chain length that can be achieved, and a second series is obtained by an alternative synthesis strategy based on acetylation of well-defined linear poly(ethylene imine) (PEI) prepared by controlled side-chain hydrolysis of a defined high molar mass of poly(2-ethyl-2-oxazoline). The combination of these two series of PMeOx allowed the determination of the Kuhn-Mark-Houwink-Sakurada equations in a broad molar mass range. For intrinsic viscosity, sedimentation and diffusion coefficients, the following expressions were obtained: η=0.015M0.77, s0=0.019M0.42 and D0=2600M-0.58, respectively. As a result, it can be concluded that the phosphate-buffered saline buffer at 37 °C represents a thermodynamically good solvent for PMeOx, based on the scaling indices of the equations. The conformational parameters for PMeOx chains were also determined, revealing an equilibrium rigidity or Kuhn segment length, (A) of 1.7 nm and a polymer chain diameter (d) of 0.4 nm. The obtained value for the equilibrium rigidity is very similar to the reported values for other hydrophilic polymers, such as PEG, poly(vinylpyrrolidone) and poly(2-ethyl-2-oxazoline), making PMeOx a relevant alternative to PEG.

Keywords: PMeOx; biomedical applications; conformation; equilibrium rigidity; molecular hydrodynamic; poly(2-methyl-2-oxazoline); thermodynamical solvent quality.

Grants and funding

22-13-00187/Russian Science Foundation