Ultrathin, anti-biofouling, polymer coating for optical devices
Scientists report high transparency and robust antibacterial performance for underwater imaging, medical optics and touch display interfaces.
The coating is claimed to overcome the trade-off between the adhesion of microorganisms and the performance of optical devices, according to the team at Ningbo Institute of Materials Technology and Engineering at the Chinese Academy of Sciences.
They think it has promise for applications where optical clarity and long-term resistance to biofouling are critical.
To make the coating, they first fabricated a poly(methacrylic acid) brush layer with a thickness of about 52nm on a substrate. They then incorporated transition metal ions, such as copper and silver, through coordination with the brush's carboxyl groups. which were then reduced using dimethylformamide to form the metalated polymer brush coating.
The final coating thickness was measured at ~60.07nm for the copper-incorporated version and at ~57.45nm for the silver-incorporated version.
The researchers report that X-ray photoelectron spectroscopy reveals the presence of both metallic and oxide states on the surface, with atomic ratios of 7.49% for copper and 7.12% for silver. Despite the metal addition, the coating maintains a high optical transmittance of approximately 86%.
The group also found the metalated polymer brush coating to achieve an inhibition rate of ~99.99% against both Escherichia coli and Staphylococcus aureus, far exceeding the performance of the polymer brush alone. The coating also exhibits notable antifouling properties, showing minimal adhesion of model proteins in laboratory tests.
For validation, they coated a camera lens with the copper-incorporated version and immersed it in natural outdoor water - both clear and turbid - for 31 days. The lens was found tp consistently transmit high-resolution images.
The optical transmittance of the coated glass decreases by less than 2%, and the surface atomic ratio of copper shows only a slight decrease from 7.49-7.12%.
