Properties and reactivity of polyoxazoline plasma polymer films

Abstract

Polyoxazolines arise as a promising new class of polymers for biomedical applications, but creating oxzoline-based coatings via conventional methods is challenging. Herein, nanoscale polyoxazoline coatings were generated via a single step plasma deposition process. The effects of plasma deposition conditions on the film stability, structure and chemical group density were investigated. Detailed examination of the physical and chemical properties of plasma deposited polyoxazoline via XPS, FTIR, contact angle and ellipsometry unravels the complex functionality of the films. Partial retention of the oxazoline ring facilitates covalent reaction with the carboxylic acid groups present on nanoparticulates and biomolecules. Surface bound proteins effectively retain their bioactivity, therefore a vast range of potential applications unlocks for plasma deposited polyoxazoline coatings in the field of biosensing, medical arrays and diagnosis. 20 Graphical abstract Nanoscale polyoxazoline coatings generated via a single step plasma deposition process are investigated. The complex functionality of the film can be controlled by varying the deposition conditions. Partial retention of the oxazoline ring facilitates covalent binding of nanoparticules and biomolecules.

Deposition of 2‐oxazoline‐based plasma polymer coatings using atmospheric pressure helium plasma jet

“…It is anticipated that low degree of polymerisation would lead to a reduction in the plasma film crosslinking and poor adhesion to the substrate. This scenario was in good agreement with the findings from other studies where low powers were applied during plasma polymerisation of OX precursors . This is also valid for plasma processes of other precursors …”

“…There are parameters in each technique that can influence the final quality of the deposited plasma coating. The plasma coatings presented in this study, which are obtained by atmospheric pressure plasma jet tend to be more oxidised compared with those obtained by vacuum plasmas . This can be explained by the fact that the plasma jet was running with helium in an open air environment, which results in a higher oxidation of the precursor during the plasma polymerisation process.…”

“…This scenario was in good agreement with the findings from other studies where low powers were applied during plasma polymerisation of OX precursors. [31,35,36,43] This is also valid for plasma processes of other precursors. [47,48] To enhance the OXpp coatings' stability and substrate adhesion, the plasma polymerisation process was performed on heated substrates.…”

“…This makes the process cost‐effective, commercially attractive and environmentally friendly. Recently, our team pioneered low‐pressure RF plasma for the deposition of oxazoline‐based coatings for biomedical applications utilising 2‐methyl‐2‐oxazoline (OX) and 2‐ethyl‐2‐oxazoline as precursors . By tuning extrinsic plasma parameters such as applied RF power, plasma mode, duty cycle, and oxazoline monomer flow rate it was possible to achieve plasma coatings with excellent stability, biocompatibility and low biofouling properties.…”

“…Recently, our team pioneered low-pressure RF plasma for the deposition of oxazoline-based coatings for biomedical applications utilising 2-methyl-2-oxazoline (OX) and 2-ethyl-2-oxazoline as precursors. [29][30][31][32][33][34] By tuning extrinsic plasma parameters such as applied RF power, plasma mode, duty cycle, and oxazoline monomer flow rate it was possible to achieve plasma coatings with excellent stability, biocompatibility and low biofouling properties. In addition, it was found that those coatings are capable of reacting with carboxylic acid functionalised biomolecules.…”