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

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.

Pullulan-Graft-Polyoxazoline: Approaches from Chemistry and Physics

“…The obtained values are shown in Table 2. The average value of A0 = (3.14 ± 0.22) × 10 −10 g cm 2 /(s 2 K mol 1/3 ) is typical for flexible-chain and semi-rigid polymers in good and theta solvents and is close to the one obtained earlier in a wide molar mass range series of poly(2-methyl-oxazoline)s [36,52]. Thus, the mutual agreement of the characteristics was proved, and the determination of molar masses using the Svedberg equation is possible.…”

“…A recent study on PMeOx using X-ray scattering established the interesting fact that poly(2-methyl-2-oxazoline) is not completely amorphous [35]. Conformation of PMeOx under physiological conditions has been reported recently [36]. Poly(2-oxazoline)s are considered to be appropriate alternatives to PEG, since PEG antibodies are being reported repeatedly [37][38][39].…”

Exploring Waste Wool Derived-Keratin Nanofiber Architectures on Cotton Fabrics: Electrospinning Strategies for Enhanced Material Properties

“…Conversely, partial hydrolysis of PEtOx to create PEtOx- co -PEI reduced molecular weight during membrane dialysis, causing alterations in the solution’s viscoelastic characteristics . The viscosity of a blend of KerSH (12.5%) and PEtOx- co -PEI (20%) was 74.5 cP.…”

“…Conversely, partial hydrolysis of PEtOx to create PEtOx-co-PEI reduced molecular weight during membrane dialysis, causing alterations in the solution's viscoelastic characteristics. 40 The viscosity of a blend of KerSH (12.5%) and PEtOxco-PEI (20%) was 74.5 cP. Thus, it could not create the required intermolecular entanglements with KerSH, which is essential for maintaining the jet's integrity during electrospinning.…”

Chelate-functionalized poly(2-oxazoline) for the destruction of bacterial cell membranes

“…S5A in the ESI †). Such behavior was also observed for other poly(2-oxazoline)s. [45][46][47][48] In the final step, POx-NH 2 was modified with the monoactivated DOTA (DOTA-NHS) chelating agent (Fig. 1).…”