Abstract
Zwitterionic polymer brushes possess a high potential for applications as surface coatings, e.g., in antifouling applications. Their complex association behavior due to the coexistence of oppositely charged groups on the same monomeric unit allows for a broad variation of polarity, hydrophilicity, and the antipolyelectrolyte effect with the variation of the surrounding environment. In this study, planar polysulfobetaine brushes were investigated with neutron reflectometry (NR) and neutron spin-echo spectroscopy under grazing incidence (GINSES) to explore the brush structure and its inner dynamics perpendicular to the substrate. In particular, the effects of the substrate-initiator system and ionic strength on the structure were investigated with neutron reflectometry and a swelling by a factor of 3-5 was found in the presence of aqueous NaCl and MgCl2 solutions compared to the dry state. During the data analysis, the applicability of a model-free evaluation was also demonstrated for the investigated polysulfobetaine brushes. Furthermore, it was found with GINSES that in contrast to neutral brushes, these polysulfobetaine brushes do not show the typical concentration fluctuations in the nanosecond time range when partially swollen with salt-free water.
| Original language | English |
|---|---|
| Pages (from-to) | 5807-5819 |
| Number of pages | 13 |
| Journal | ACS Applied Polymer Materials |
| Volume | 7 |
| Issue number | 10 |
| DOIs | |
| State | Published - May 23 2025 |
| Externally published | Yes |
Funding
The dynamics part of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. This work is based upon experiments performed at the Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany. Neutron reflectometry measurements were performed at the ILL, Grenoble, and the HZB, Berlin. We thank Luca Silvi for his assistance with the measurements at the HZB. Parts of the laboratory work were conducted in the Lahann Lab at the University of Michigan. Water contact angle measurements were conducted in the PSI Lab at the University of Michigan. Therefore, we would like to thank Professor Lahann and Professor Tuteja for providing resources. The author S.M. thanks the PSCM platform for granting access to the infrastructure for sample preparation.
Keywords
- brushes
- grazing incidence
- neutron reflectometry
- neutron spin - echo
- zwitterionic