Fabrication of Chitosan‐Derived Microspheres With Superhydrophobicity and Antibacterial Activity for Functional Coating Applications

In this work, superhydrophobic chitosan microspheres were fabricated via spray drying of chitosan aqueous solution followed by surface silanization modification. Characterization methods, namely laser particle size analysis, SEM, and FTIR, were adopted to systematically investigate the particle size distribution, micromorphology, and chemical composition of chitosan microspheres. Experimental results revealed the dissolution medium exerted a remarkable effect on the microscopic morphology of as‐prepared microspheres. Hydrophobicity characterization verified the silanized chitosan microspheres possessed excellent hydrophobic performance with a water contact angle of 153.3°. Antibacterial assays confirmed that the modified chitosan microspheres exhibited an antibacterial efficiency of 95.42% against Escherichia coli . Furthermore, functional composite coatings were constructed by uniformly spraying the modified chitosan microspheres onto filter paper substrates. The coated filter paper presented a water contact angle of 152.1°, which enabled it to achieve efficient separation of oil–water mixtures. Notably, the modified filter paper retained a water contact angle over 150.0° after immersion in acidic, neutral, and weakly alkaline solutions and maintained stable superhydrophobicity even after 90 cycles of weighted friction tests. This study proposes feasible technical strategies for the functional modification of chitosan microspheres and offers valuable references for their practical deployment as coating materials in functional filter paper fabrication.