Microsphere with narrow nanopores: Fabrication in PVDF/PMMA/PLLA blend and enhanced adsorption/separation performances

Abstract

In this work, a novel strategy for fabricating microsphere with narrow nanopores in PVDF/PMMA/PLLA blend has been reported. In the ternary blend, phase separation results in isolated PVDF/PMMA mixed-phase and PLLA matrix. In the former, the crystallization of PVDF produces bi-continuous nanostructures of two phases. Upon etching with chloroform, both PLLA matrix and continuous PMMA in islands can be removed, yielding PVDF microspheres with narrow nanopores. According to the templates of phase separation and crystallization, the size of microsphere and narrow nanopore can be tailored precisely and separately. Relative to the reference (compact spheres), the porous PVDF microspheres exhibit enhanced performances. On one hand, the special wettability caused by hierarchical roughness and extra nano-channels endow the membrane comprising porous PVDF microspheres with excellent performance during the separation of water-in-chloroform emulsion. On the other hand, the stronger capillary effect (resulted from pore shape and pore size) and the existence of interpenetrated nanopores account for the higher capacity in the absorption of oil. Furthermore, it is facile to load nano-Fe3O4 in the porous microspheres to achieve magnetic controllability. Our results provide a novel strategy for not only the fabrication of microsphere with narrow nanopores, but also the improvement of separation and absorption performances.