Functional groups docking on PVDF membranes: Novel Piranha approach

Polyvinylidene fluoride (PVDF) membranes play a key role in several industrial applications due to their favorable properties, including their high chemical stability. Tuning the properties of PVDF membranes enables a sharp selectivity for the target application. One of the direct methods to achieve this goal is the selective activation of PVDF membranes with labile groups like OH. In this work, a novel effective method of PVDF activation, using the Piranha-reaction approach as a precursor step, was developed to produce functionalized PVDF flat sheet membranes. The Piranha reagent was utilized at mild conditions of temperature (RT), concentration (20%) and time of treatment (from 0.5 to 30 min) to activate the PVDF membrane surface. Activated membranes were then successfully functionalized using (3-aminopropyl)triethoxysilane. The resultant docking of amine groups on the surface was confirmed with several spectroscopic and thermal tools as well as by Kaiser test. The properties of the membrane were evaluated and characterized using a wide range of tools. Extensive physicochemical (e.g., contact angle, surface free energy, surface tension, and work of adhesion) and morphological (e.g., pore size distribution and roughness) characterization of the prepared membranes was done applying goniometric and microscopic, methods.