Porous Poly(4-vinylpyridine) Coatings Prepared by Electrostatic Slurry Spray Deposition: Morphological Control and Preliminary Formaldehyde-Reduction Assessment

Porous poly(4-vinylpyridine) (P4VP) coatings were fabricated by electrostatic slurry spray deposition (ESSD) using solution and ethanol–water composite-slurry precursors. Thirty-four solvents were screened to examine the relationship between precursor formulation, spray behavior, and deposited morphology. Gradual nonsolvent addition generated a particulate composite slurry, with a principal volume-weighted dynamic light scattering (DLS) peak at 13.78 nm for the 7.4 wt.% formulation. Under the investigated conditions, this slurry produced a more spatially uniform porous coating than the solution precursor and was successfully deposited onto a three-dimensional fibrous filter scaffold. During a preliminary 30 m3 chamber assessment of the air-purifier system equipped with the coated filter, formaldehyde (HCHO) concentration decreased from 0.846 to 0.702 ppm in 1 h, corresponding to an apparent concentration-decay-based air-cleaning rate (Qapp) of approximately 5.69 m3 h−1. This preliminary observation describes the performance of the assembled air-purifier system; the principal contribution of the study is the formulation and morphological control of porous P4VP coatings through composite-slurry ESSD.