2 research outputs found
Synthesis of Hierarchical Micro/Mesoporous Structures via Solid–Aqueous Interface Growth: Zeolitic Imidazolate Framework‑8 on Siliceous Mesocellular Foams for Enhanced Pervaporation of Water/Ethanol Mixtures
A new hierarchical micro/mesoporous
composite is synthesized via
direct growth of microporous zeolitic imidazolate framework-8 (ZIF-8)
on siliceous mesocellular foams (MCF). Depending on different synthetic
conditions, ZIF-8 with two different particle sizes, i.e., ZIF-8 microparticles
and ZIF-8 nanoparticles, were successfully formed on the external
surface of amine-functionalized MCF (denoted as microZIF-8@MCF and
nanoZIF-8@MCF, respectively). The synthesized hierarchical micro/mesoporous
ZIF-8@MCF structures were characterized with several spectroscopic
techniques including X-ray diffraction (XRD), solid-state NMR, and
FT-IR and electron microscopic techniques (scanning electron microscope,
SEM, and transmission electron microscopy, TEM). In addition, the
pervaporation measurements of the liquid water/ethanol mixture show
that nanoZIF-8@MCF/PVA (polyÂ(vinyl alcohol) mixed-matrix membrane
exhibits enhanced performance both on the permeability and separation
factor. Compared to conventional routes for chemical etching, this
study demonstrates a promising and simple strategy for synthesizing
novel hierarchical porous composites exhibiting both advantages of
mesoporous materials and microporous materials, which is expected
to be useful for gas adsorption, separation, and catalysis
Surface Self-Assembled PEGylation of Fluoro-Based PVDF Membranes via Hydrophobic-Driven Copolymer Anchoring for Ultra-Stable Biofouling Resistance
Stable
biofouling resistance is significant for general filtration
requirements, especially for
the improvement of membrane lifetime. A systematic group of hyper-brush
PEGylated diblock copolymers containing polyÂ(ethylene glycol) methacrylate
(PEGMA) and polystyrene (PS) was synthesized using an atom transfer
radical polymerization (ATRP) method and varying PEGMA lengths. This
study demonstrates the antibiofouling membrane surfaces by self-assembled
anchoring PEGylated diblock copolymers of PS-<i>b</i>-PEGMA
on the microporous polyÂ(vinylidene fluoride) (PVDF) membrane. Two
types of copolymers are used to modify the PVDF surface, one with
different PS/PEGMA molar ratios in a range from 0.3 to 2.7 but the
same PS molecular weights (MWs, ∼5.7 kDa), the other with different
copolymer MWs (∼11.4, 19.9, and 34.1 kDa) but the similar PS/PEGMA
ratio (∼1.7 ± 0.2). It was found that the adsorption capacities
of diblock copolymers on PVDF membranes decreased as molar mass ratios
of PS/PEGMA ratio reduced or molecular weights of PS-<i>b</i>-PEGMA increased because of steric hindrance. The increase in styrene
content in copolymer enhanced the stability of polymer anchoring on
the membrane, and the increase in PEGMA content enhanced the protein
resistance of membranes. The optimum PS/PEGMA ratio was found to be
in the range between 1.5 and 2.0 with copolymer MWs above 20.0 kDa
for the ultrastable resistance of protein adsorption on the PEGylated
PVDF membranes. The PVDF membrane coated with such a diblock copolymer
owned excellent biofouling resistance to proteins of BSA and lysozyme
as well as bacterium of <i>Escherichia coli</i> and <i>Staphylococcus epidermidis</i> and high stable microfiltration
operated with domestic wastewater solution in a membrane bioreactor