Zwitterionic modified electrostatic flocking surfaces for diatoms and mussels resistance

Area of Science:

• Materials Science
• Surface Chemistry
• Biotechnology

Background:

• Biocide-releasing antifouling coatings pose environmental risks.
• Development of non-biocidal, environmentally friendly antifouling solutions is essential for marine applications.
• Surface properties play a critical role in preventing biofouling.

Purpose of the Study:

• To develop and evaluate a novel zwitterionic electrostatic flocking surface (ZEFS) as a biocide-free antifouling coating.
• To investigate the antifouling performance of ZEFS against diatoms and mussels.
• To understand the mechanisms behind the antifouling properties of ZEFS.

Main Methods:

• Fabrication of ZEFS using electrostatic flocking and free radical polymerization of poly(sulfobetaine methacrylate) (PSBMA).
• Assessment of diatom resistance based on fiber diameter relative to diatom size.
• Evaluation of mussel adhesion by quantifying plaque reduction compared to control surfaces (glass and PDMS).
• Measurement of surface hydrophilicity using underwater oil contact angle.
• Testing of zwitterionic layer stability in artificial seawater.

Main Results:

• ZEFS demonstrated resistance to diatoms due to sub-diatom-sized fiber diameters.
• Mussel adhesion was significantly reduced on ZEFS, with plaque numbers decreasing by over 98% compared to glass and 96% compared to PDMS after 4 days.
• The vertical fiber morphology hindered seawater expulsion by mussels, and zwitterionic modification further enhanced anti-adhesion.
• ZEFS exhibited high hydrophilicity (underwater oil contact angle of 152°), reducing protein adhesion work and wettability.
• The zwitterionic layer showed excellent stability, retaining over 96% stability after 30 days in artificial seawater.

Conclusions:

• ZEFS offer a promising biocide-free antifouling solution with dual mechanisms: physical barrier and zwitterionic surface properties.
• The unique surface structure and zwitterionic nature of ZEFS effectively prevent fouling by both diatoms and mussels.
• ZEFS demonstrate good durability in marine environments, making them suitable for long-term antifouling applications.