HPW/PDMAEMA-b-PMAA/ZIF-8 Ternary Lamellar Composite and the Photocatalytic Degradation of Methylene Blue.

Abstract

PDMAEMA-b-PMAA block copolymers were prepared by the sequential RAFT polymerization of DMAEMA and tBMA, followed by hydrolysis. Phosphotungstic acid (HPW) was anchored to the PDMAEMA blocks through electrostatic interactions and the as-obtained HPW/PDMAEMA-b-PMAA was added to the synthesis of ZIF-8. During the formation of ZIF-8, the PMAA blocks coordinated to the Zn2+ ions through their carboxy groups, along with the HPW groups that were anchored to the PDMAEMA blocks. In this way, the block copolymer could consolidate the interactions between HPW and ZIF-8 and prevent the leakage of HPW. Finally, the HPW/PDMAEMA-b-PMAA/ZIF-8 ternary lamellar composite was obtained and the structure of the HPW/PDMAEMA-b-PMAA/ZIF-8 hybrid material was characterized by using powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). As a photocatalyst, the HPW/PDMAEMA-b-PMAA/ZIF-8 ternary lamellar composite showed excellent photoactivity for the degradation of methylene blue (MB). The rate of degradation of MB was 0.0240 min-1 , which was 7.5-times higher than that of commercially available P25 (0.0032 min-1 ). In the presence of H2 O2 , the kinetic degradation parameters of the composite reached 0.0634 min-1 , which was about 19.8-times higher than that of P25.