PFAS-free superhydrophobic chitosan coating for fabrics

Area of Science:

• Materials Science
• Surface Chemistry
• Textile Engineering

Background:

• Growing concerns over per- and polyfluoroalkyl substances (PFAS) necessitate the development of safer, environmentally friendly alternatives for surface hydrophobization.
• Polysaccharides, particularly chitosan, offer promising properties for creating functional coatings due to their film-forming capabilities and modifiability.

Purpose of the Study:

• To develop and characterize a per- and polyfluoroalkyl substances (PFAS)-free superhydrophobic coating for textiles utilizing chitosan.
• To evaluate the coating's hydrophobicity, durability, degradation profile, and biocompatibility.

Main Methods:

• Solvent-free deposition of a modified chitosan coating onto textiles.
• Contact angle analysis and drop impact tests to assess superhydrophobicity.
• Scanning Electron Microscopy (SEM) for surface morphology analysis.
• Thermogravimetric analysis coupled with Infrared spectroscopy (TGA-IR) for thermal degradation studies.
• Biochemical oxygen consumption tests for biodegradability assessment.
• In vitro biocompatibility testing on keratinocyte (HaCaT) and fibroblast (HFF-1) cell lines.

Main Results:

• The chitosan coating achieved superhydrophobicity (contact angles up to 151°/136°) with increasing coating amounts.
• SEM analysis confirmed the presence of nano- and micro-scale roughness contributing to the superhydrophobic effect.
• The coating demonstrated good durability, particularly retaining hydrophobicity through 8 acidic soaking and washing cycles.
• TGA-IR analysis identified released compounds during thermal degradation, and biodegradability was confirmed via oxygen consumption.
• Biocompatibility tests showed the coating is safe for human skin cells (keratinocytes and fibroblasts).

Conclusions:

• A novel, PFAS-free, solvent-free chitosan coating effectively imparts superhydrophobicity to textiles.
• The coating exhibits promising durability, biodegradability, and biocompatibility, presenting a sustainable alternative to conventional treatments.
• This research addresses the need for environmentally conscious materials in surface treatment applications.