Mechanistic Study of Rhodamine B Piezocatalytic Decomposition Using Poly(vinylidene difluoride) and Related Polymers
Benjamin Cromwell, Mara Dubnicka, Lasanthi Sumathirathne, Angela Thach, William B. Euler, J. Phys. Chem. C, 2023, 127, 11940 - 11947.
Abstract
Membranes of poly(vinylidene difluoride) (PVDF) and related polymers are used as piezoelectric materials to decompose rhodamine B (RhB) under low power sonication. The change in the visible spectrum of RhB allows determination of the rate constants for different polymer compositions and membrane thicknesses. The results indicate that the piezoelectric field generated by mechanical deformation of the polymers catalyzes the scission of the C−N bond in RhB. When PVDF is doped with transition-metal nitrates to increase the fraction of the piezoelectric β-phase, the rate constants increase, but the analysis is complicated by concurrent adsorption of RhB onto the membrane. A mechanism consistent with the observed data is proposed where the piezocatalytic effect of the membrane is to heterolytically cleave the C−N bond followed by formation of a C−Cl bond on the new xanthene ring.
