Optimization of Plasma Treatment Parameters for PVDF Membrane Surface Modification: Balancing Activation and Structural Integrity

ABSTRACT

Atmospheric plasma treatment effectively activates poly(vinylidene fluoride) (PVDF) membrane surfaces, improving wettability and adhesion for subsequent modification, but excessive exposure risks degradation via dehydrofluorination and loss of the electroactive β‐phase. Here, we systematically investigate key plasma parameters (current: 0.3–1.1 A; power: 15.4–32.2 W; duration: 3–8 min) using SEM, XPS, FTIR, WCA, and tensile testing. A narrow optimal window (0.7 A, 30 W, 4 min) brings surface oxidation to its plateau (10.54 at.% O by XPS) while retaining a high β‐phase content (73.5% vs. 77.1% pristine, within uncertainty). Under these conditions, the membrane becomes superhydrophilic (WCA reduced from 104.4° to 5.4°), giving a 42‐fold increase in deionized‐water flux to 4574 L/(m ² ·h). In contrast, prolonged treatment triggers progressive dehydrofluorination (32.3% rise in CC absorbance relative to the optimum), α‐phase enrichment (84.1% increase in Aα relative to the pristine membrane), fluorine depletion (surface F/C from 0.90 to 0.70 by XPS), and mechanical degradation (23.4% and 30.6% losses in tensile strength and Young's modulus). The optimum retains more than 98% of the original tensile strength with only a 12.7% reduction in stiffness. These quantitative boundaries link plasma chemistry, crystalline‐phase integrity, and mechanical performance, guiding plasma pretreatment of PVDF microfiltration membranes.