Unique nanoporous antibacterial membranes derived through crystallization induced phase separation in PVDF/PMMA blends

Abstract

In this study, a unique method was adopted to design porous membranes through crystallization induced phase separation in PVDF/PMMA (poly(vinylidene fluoride)/poly(methyl methacrylate)) blends. By etching out PMMA, which segregates either in the interlamellar and/or in the interspherulitic regions of the blends, nanoporous hierarchical structures can be derived. Different nanoparticles like titanium dioxide (TiO 2 ), silver nanoparticle (Ag) decorated carbon nanotubes (Ag-CNTs), TiO 2 decorated CNTs (TiO 2 -CNTs), Ag decorated TiO 2 (Ag-TiO 2 ) and Ag-TiO 2 decorated CNTs (Ag@TiO 2 -CNTs) were synthesized and melt mixed with 80/20 PVDF/PMMA blends to render antibacterial activity to the membranes.Scanning electron microscopy (SEM) was used to study the crystalline morphology of the membranes. A significant improvement in the trans-membrane flux was obtained in the blends with Ag@TiO 2 decorated CNTs as compared to the membranes derived from the neat blends, which can be attributed to the interconnected pores in these membranes. Both qualitative and quantitative studies of antifouling and antibacterial activity (using E. coli as a model bacterium) were performed using the standard plate count method. SEM micrographs clearly showed that the antifouling activity of the membranes was improved with addition of Ag@TiO 2 -CNTs. In the quantitative standard plate count method, the bacterial colony significantly decreased with the addition of Ag@TiO 2 -CNTs as against neat blends. This study opens a new avenue in the fabrication of polymer blend based membranes for water filtration.

From hydrophobic to hydrophilic polyvinylidenefluoride (PVDF) membranes by gaining new insight into material's properties

“…The four types of MWCNTs are used to prepare composite membranes following protocol A and fixing the carbon nanotubes loading at 1 wt. 38,39 The membranes prepared by protocol A are characterized by a more compact structure (less porous) with less elongated finger-like macrovoids than those prepared by protocol B (Figure 4-5). In agreement with the preliminary dispersion tests in organic solvent, membranes containing thermally treated MWCNTs show the poorest dispersion in the polymeric matrix (Figure 3a), while the most homogeneous dispersion is obtained with the oxidized sample ( Figure 3d).…”

In situ assembly of a graphene oxide quantum dot-based thin-film nanocomposite supported on de-mixed blends for desalination through forward osmosis

“…Blends of PVDF/PMMA with different compositions (50/50, 60/ 40, and 70/30) were melt processed using a Minilab II HAAKE extruder CTW5 (7 cm 3 ) at 220 C with 60 rpm screw speed for 20 min as reported in the literature. 22 60 mm compression molded discs with 80 mm thickness were made using a laboratory hot press at 220 C. The membranes were then obtained by selectively etching with glacial acetic acid for 7 days to remove the PMMA phase from the blends. By stacking these membranes using PAA solution (0.08 g mL À1 THF), a unique hierarchical architecture was obtained.…”

“…13 To this end, PVDF is used extensively as a membrane material due to its better chemical and thermal resistance, and excellent mechanical strength. For a semi-crystalline polymer like PVDF, Sharma et al 6,22,23 devised a unique strategy for membrane fabrication by selectively etching one of the phase from a binary blend processed via melt mixing. 17 Using different compositions of this binary blend different pore sizes and distributions can be tailored.…”

Enhanced Temperature Stability of High Energy Density Ferroelectric Polymer Blends: The Spatial Confinement Effect

“…Because rubbery‐state amorphous region above T g , which manifests itself as loose chains with increased free volume, becomes vulnerable to temperature rise . Recent investigations even point out that high‐ T g non‐ferroelectric polymers can maintain an energy density around 0.5–1.8 J cm −3 up to a fairly high temperature . Nonetheless, for ferroelectric polymers, it remains a considerable challenge to achieve high energy storage performance at the elevated temperature.…”