The future of poly(2-oxazoline)s

Hoogenboom, Richard

doi:10.1016/j.eurpolymj.2022.111521

Cited by 36 publications

(23 citation statements)

References 154 publications

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“…To date, PEtOx appears to be the most investigated poly(2-oxazoline) in terms of biomedical applications [ 7 , 10 , 14 , 15 , 16 , 27 ], and PEtOx based polymer-drug conjugates and hemostatic materials have also reached human clinical trials [ 28 , 29 , 30 , 31 ]. Nonetheless, PMeOx is an important runner-up, and is especially attractive to shield drug carriers and for antifouling coatings based on its hydrophilicity, which is higher than that of PEtOx and PEG [ 17 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2023

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2023

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“…In the two last decades, poly(2-ethyl-2-oxazoline) (PEtOx) has received considerable attention in the field of biomedical and pharmaceutical applications, − including polymer–prodrug conjugates, − hydrogels, − and matrix excipients. − Furthermore, hydrolysis of PEtOx affords linear poly(ethylene imine) (PEI), − which is the “gold standard” among cationic polymer transfection agent for delivery of nucleic acids. − As reproducible synthesis and narrow dispersity (for therapeutics) are key parameters for such biomedical applications, an in-depth understanding of the synthesis of PEtOx via living cationic polymerization is important. In this work, we addressed the question what the best solvent is for the polymerization of EtOx with respect to polymer solubility, monomer reaction rate, and polymer dispersity.…”

Section: Introductionmentioning

confidence: 99%

Detailed Understanding of Solvent Effects for the Cationic Ring-Opening Polymerization of 2-Ethyl-2-oxazoline

Vergaelen

Monnery

Jerca³

et al. 2023

Macromolecules

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Polymerization of 2-ethyl-2-oxazoline (EtOx) has often been in the spotlight for fundamental studies of poly(2-alkyl/ aryl-2-oxazoline)s (PAOx) polymerization, especially initiator screening, solvent screening, and copolymerization trends. In this work, we build on previous observations of solvent effects on the cationic ring-opening polymerization (CROP) of EtOx, with additional experimental observations of previously unreported solvents to expand the explored parameter space. Our objective is to find solvents with the lowest activation energy (E a ) and higher Arrhenius preexponential factor (A), which will allow us to produce narrow molar mass distributions at higher molecular weights, in the least time. To achieve this, we examined the various single factors like Dimroth E T (30) values, the Kamlet−Abraham−Taft (KAT) linear free-energy relationship (LFER) equation(s), and the Catalan LFER equations. Only one of Catalan's equations sufficiently disentangled dipolarity and polarizability to give a good fit due to contradictory effects. It was found that solvent nucleophilicity, electrophilicity, and polarizability affected the E a , but not dipolarity. All four factors affected the A. This indicates that the E a is minimized in solvents that do not solvate ions well (i.e. force ion-pairing), and A was minimized in more dipolar solvents that solvate the polymer chains well. A strongly negative activation entropy (ΔS ‡ ) shows that the propagation reaction is associative. The Catalan LFER allows for the prediction of E a , A, ΔH ‡ , and ΔS ‡ , and the derived k p , across a broad range of solvents.

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“…Surprisingly, we found that this polymerization reaction is very sensitive to temperature and results in successful synthesis of poly(2-oxazoline)s with elevated temperature, suggesting a classical mechanism for 2-oxazoline polymerization. 49 This polymerization gave poly(2-oxazoline)s with variable side chains with controllable molecular weights and high yields within 1–8 hours (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Controllable and facile synthesis of poly(2-oxazoline)s using trimethylsilyl trifluoromethanesulfonate as the initiator

Zhou

Xiao

et al. 2023

Polym. Chem.

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The future of poly(2-oxazoline)s

Cited by 36 publications

References 154 publications

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

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

Detailed Understanding of Solvent Effects for the Cationic Ring-Opening Polymerization of 2-Ethyl-2-oxazoline

Controllable and facile synthesis of poly(2-oxazoline)s using trimethylsilyl trifluoromethanesulfonate as the initiator

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