8 research outputs found
Preparation of Hydrophobic Functionalized Poly(vinyl alcohol) Formaldehyde-Based Composite Sponges for Highly Effective Water-in-Oil Emulsion Separation
Three-dimensional
porous materials featuring unique pore
structures
and wettability properties have shown great potential for emulsion
separation. However, their practical utilization in industrial settings
is hampered by their inability to sustain a high separation flux and
efficiency during the separation process. To address these challenges,
we developed composite sponges based on poly(vinyl alcohol) formaldehyde
(PVF) with a hierarchical pore structure. This was achieved through
secondary chemical cross-linking of poly(vinyl alcohol) (PVA), followed
by additional hydrophobic modification using grafting polymerization
of various methacrylate monomers. Typically, the resultant typical
PVF/PVA-Mac-PEMA sponge exhibits an average pore size of 24 ÎĽm
and hydrophobic networks with a water contact angle of 133.3°.
The intriguing sponges possess notable potential for effectively separating
water-in-oil emulsions driven solely by gravity, achieving a maximum
flux of 5.40 × 105 L m–2 h–1 bar–1 and separation efficiency exceeding 99.72%,
respectively. The PVF-based composite sponges display remarkable reusability
and long-term stability, which remain nearly unchanged even after
undergoing 10 cycles and continuous use for 30 min. Furthermore, their
ability to be easily restored through washing renders them suitable
candidates for practical applications. These merits make them highly
promising for applications requiring prolonged and repetitive operation
Synthesis and Multi-Stimuli-Responsive Behavior of Poly(<i>N</i>,<i>N</i>‑dimethylaminoethyl methacrylate) Spherical Brushes under Different Modes of Confinement in Solution
We
report the synthesis and solution behavior of photo-, temperature-,
pH-, and ion-responsive weak polyelectrolyte spherical brushes under
different modes of confinement. The spherical brushes were prepared
by copolymerization of <i>N</i>,<i>N</i>-dimethylaminoethyl
methacrylate (DMAEMA) and 7-(2-methacryloyloxyethoxy)-4-methylcoumarin
anchored to silica nanoparticles via surface-initiated atom transfer
radical polymerization. The photo-cross-linking and reversibility
of the nanoparticle-attached coumarin entities are detected by UV–visible
spectroscopy and dynamic light scattering (DLS). The cross-linking
density of polyÂ(DMAEMA) (i.e., PDMAEMA) brushes could be easily controlled
by alternating irradiation at wavelengths of 365 and 254 nm. Moreover,
solution behavior under different pH levels and ionic strengths is
systematically investigated in the PDMAEMA brush–polyelectrolyte
chains confined only by a hard core, the cross-linked PDMAEMA brush–polyelectrolyte
chains confined by a hard core and cross-linking points, and the corresponding
hollow nanocapsules after removal of silica by etching-polyelectrolyte
chains confined only by cross-linking points. These three models represent
the different modes of confinement. DLS results indicate that the
volume phase transition temperatures of the three models shift to
lower temperatures with the increase in pH. The highest temperature
is afforded to phase transition for hollow nanocapsules in solution,
followed by the cross-linked PDMAEMA brushes. The hydrodynamic radius
of the polyelectrolyte brush systems obviously decreases with the
increase in ionic strength of the solution when adjusted by NaCl
Phase Behavior of Poly(sulfobetaine methacrylate)-Grafted Silica Nanoparticles and Their Stability in Protein Solutions
Biocompatible and zwitterionic poly(sulfobetaine methacrylate) (PSBMA) was grafted onto the surface of initiator-modified silica nanoparticles via surface-initiated atom transfer radical polymerization. The resultant samples were characterized via nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Their molecular weights and molecular weight distributions were determined via gel permeation chromatography after the removal of silica by etching. Moreover, the phase behavior of these polyzwitterionic-grafted silica nanoparticles in aqueous solutions and stability in protein/PBS solutions were systematically investigated. Dynamic light scattering and UV–visible spectroscopy results indicate that the silica-<i>g</i>-PSBMA nanoparticles exhibit an upper critical solution temperature (UCST) in aqueous solutions, which can be controlled by varying the PSBMA molecular weight, ionic strength, silica-<i>g</i>-PSBMA nanoparticle concentration, and solvent polarity. The UCSTs shift toward high temperatures with increasing PSBMA molecular weight and silica-<i>g</i>-PSBMA nanoparticle concentration. However, increasing the ionic strength and solvent polarity leads to a lowering of the UCSTs. The silica-<i>g</i>-PSBMA nanoparticles are stable for at least 72 h in both negative and positive protein/PBS solutions at 37 °C. The current study is crucial for the translation of polyzwitterionic solution behavior to surfaces to exploit their diverse properties in the development of new, smart, and responsive coatings
Evaluation of Hydrophobic Polyvinyl-Alcohol Formaldehyde Sponges As Absorbents for Oil Spill
Macroporous materials are a class
of absorbents used for oil spill cleanup. In this article, novel macroporous
and hydrophobic polyvinyl formaldehyde (PVF-H) sponges were prepared
by the reaction of stearoyl chloride with hydroxyl groups of hydrophilic
PVF sponge at different temperatures. Attenuated total reflectance-infrared
(ATR-IR) spectroscopy confirmed the successfully anchoring of hydrophobic
stearoyl groups on the PVF networks. Scanning electron microscopy
(SEM) images demonstrated that the as-prepared PVF-H had interconnected
open-cell structures, and mercury intrusion porosimetry indicated
that the average pore size ranged from 60 to 90 ÎĽm and porosity
was greater than 94.8%. Such PVF-H sponges can absorb oil products
effectively, such as toluene, <i>n</i>-hexane, kerosene,
soybean oil, hydraulic oil, and crude oil up to 13.7 g·g<sup>–1</sup> to 56.6 g·g<sup>–1</sup>, and this level
of absorption was approximately 2–4 times higher than that
absorbed by commercial polypropylene nonwoven mat. In low-viscosity
oils, the samples can reach the saturated absorption amount only in
1 min, but in higher-viscosity oils, absorption equilibrium can be
reached in 10 min. In a simulated oil slick system, these macroporous
and hydrophobic sponges can still maintain high oil absorption capacities
within the range of 14.4 g·g<sup>–1</sup> to 57.6 g·g<sup>–1</sup>, whereas a relatively low absorption rate (approximately
20 min) indicated high absorption performance and excellent selectivity
in the oil–water mixture. In addition, the absorbed oils were
collected effectively only through a simple squeeze. The PVF-H sponges
were subjected to 35 absorption–squeeze cycles and exhibited
good reusability and 90% recovery for oils. The samples prepared at
different temperatures differed in their absorption capacities to
some extent. However, this new kind of macroporous and PVF-H sponges
had excellent absorption performance on oil products
pH Dependence of Adsorbed Fibrinogen Conformation and Its Effect on Platelet Adhesion
Quartz crystal microbalance
with dissipation (QCM-D) and dual polarization
interferometry (DPI) were used to investigate fibrinogen (Fib) adsorption
behavior on different surfaces by changing the pH value. Moreover,
integrin adhesion to the adsorbed Fibs was studied using DPI. Qualitative
and quantitative studies of platelet adhesion to the adsorbed Fibs
were performed using scanning electron microscopy (SEM), confocal
laser scanning microscope (CLSM), and released lactate dehydrogenase
(LDH) assay. Experimental results indicated that the conformation
and orientation of the absorbed Fibs depended on surface property
and pH cycling. For the hydrophilic surface, Fibs adsorbed at pH 7.4
and presented a αC-hidden orientation. As a result, no integrin
adhesion was observed, and a small number of platelets were adhered
because the αC-domains were hidden under the Fib molecule. By
changing the rinsing solution pH from 7.4 to 3.2 and then back to
7.4, the adsorbed Fib orientation became αC-exposed via the
transformation of Fib conformation during pH cycling. Therefore, integrin
adhesion was more likely to occur, and more platelets were adhered
and activated. For the hydrophobic surface, the adsorbed Fibs became
more spread and stretched due to the strong interaction between the
Fibs and surface. αC-exposed orientation remained unchanged
when the rinsing solution pH changed from 7.4 to 3.2 and then back
to 7.4. Therefore, a large number of integrins and platelets were
adhered to the adsorbed Fibs, and almost all of the adhered platelets
were activated
Evaluation of Hydrophobic Polyvinyl-Alcohol Formaldehyde Sponges As Absorbents for Oil Spill
Macroporous materials are a class
of absorbents used for oil spill cleanup. In this article, novel macroporous
and hydrophobic polyvinyl formaldehyde (PVF-H) sponges were prepared
by the reaction of stearoyl chloride with hydroxyl groups of hydrophilic
PVF sponge at different temperatures. Attenuated total reflectance-infrared
(ATR-IR) spectroscopy confirmed the successfully anchoring of hydrophobic
stearoyl groups on the PVF networks. Scanning electron microscopy
(SEM) images demonstrated that the as-prepared PVF-H had interconnected
open-cell structures, and mercury intrusion porosimetry indicated
that the average pore size ranged from 60 to 90 ÎĽm and porosity
was greater than 94.8%. Such PVF-H sponges can absorb oil products
effectively, such as toluene, <i>n</i>-hexane, kerosene,
soybean oil, hydraulic oil, and crude oil up to 13.7 g·g<sup>–1</sup> to 56.6 g·g<sup>–1</sup>, and this level
of absorption was approximately 2–4 times higher than that
absorbed by commercial polypropylene nonwoven mat. In low-viscosity
oils, the samples can reach the saturated absorption amount only in
1 min, but in higher-viscosity oils, absorption equilibrium can be
reached in 10 min. In a simulated oil slick system, these macroporous
and hydrophobic sponges can still maintain high oil absorption capacities
within the range of 14.4 g·g<sup>–1</sup> to 57.6 g·g<sup>–1</sup>, whereas a relatively low absorption rate (approximately
20 min) indicated high absorption performance and excellent selectivity
in the oil–water mixture. In addition, the absorbed oils were
collected effectively only through a simple squeeze. The PVF-H sponges
were subjected to 35 absorption–squeeze cycles and exhibited
good reusability and 90% recovery for oils. The samples prepared at
different temperatures differed in their absorption capacities to
some extent. However, this new kind of macroporous and PVF-H sponges
had excellent absorption performance on oil products
Evaluation of Hydrophobic Polyvinyl-Alcohol Formaldehyde Sponges As Absorbents for Oil Spill
Macroporous materials are a class
of absorbents used for oil spill cleanup. In this article, novel macroporous
and hydrophobic polyvinyl formaldehyde (PVF-H) sponges were prepared
by the reaction of stearoyl chloride with hydroxyl groups of hydrophilic
PVF sponge at different temperatures. Attenuated total reflectance-infrared
(ATR-IR) spectroscopy confirmed the successfully anchoring of hydrophobic
stearoyl groups on the PVF networks. Scanning electron microscopy
(SEM) images demonstrated that the as-prepared PVF-H had interconnected
open-cell structures, and mercury intrusion porosimetry indicated
that the average pore size ranged from 60 to 90 ÎĽm and porosity
was greater than 94.8%. Such PVF-H sponges can absorb oil products
effectively, such as toluene, <i>n</i>-hexane, kerosene,
soybean oil, hydraulic oil, and crude oil up to 13.7 g·g<sup>–1</sup> to 56.6 g·g<sup>–1</sup>, and this level
of absorption was approximately 2–4 times higher than that
absorbed by commercial polypropylene nonwoven mat. In low-viscosity
oils, the samples can reach the saturated absorption amount only in
1 min, but in higher-viscosity oils, absorption equilibrium can be
reached in 10 min. In a simulated oil slick system, these macroporous
and hydrophobic sponges can still maintain high oil absorption capacities
within the range of 14.4 g·g<sup>–1</sup> to 57.6 g·g<sup>–1</sup>, whereas a relatively low absorption rate (approximately
20 min) indicated high absorption performance and excellent selectivity
in the oil–water mixture. In addition, the absorbed oils were
collected effectively only through a simple squeeze. The PVF-H sponges
were subjected to 35 absorption–squeeze cycles and exhibited
good reusability and 90% recovery for oils. The samples prepared at
different temperatures differed in their absorption capacities to
some extent. However, this new kind of macroporous and PVF-H sponges
had excellent absorption performance on oil products
Fabrication of Hyperbranched Block-Statistical Copolymer-Based Prodrug with Dual Sensitivities for Controlled Release
Dendrimer
with hyperbranched structure and multivalent surface
is regarded as one of the most promising candidates close to the ideal
drug delivery systems, but the clinical translation and scale-up production
of dendrimer has been hampered significantly by the synthetic difficulties.
Therefore, there is considerable scope for the development of novel
hyperbranched polymer that can not only address the drawbacks of dendrimer
but maintain its advantages. The reversible addition–fragmentation
chain transfer self-condensing vinyl polymerization (RAFT-SCVP) technique
has enabled facile preparation of segmented hyperbranched polymer
(SHP) by using chain transfer monomer (CTM)-based double-head agent
during the past decade. Meanwhile, the design and development of block-statistical
copolymers has been proven in our recent studies to be a simple yet
effective way to address the extracellular stability vs intracellular
high delivery efficacy dilemma. To integrate the advantages of both
hyperbranched and block-statistical structures, we herein reported
the fabrication of hyperbranched block-statistical copolymer-based
prodrug with pH and reduction dual sensitivities using RAFT-SCVP and
post-polymerization click coupling. The external homo oligoÂ(ethylene
glycol methyl ether methacrylate) (OEGMA) block provides sufficient
extracellularly colloidal stability for the nanocarriers by steric
hindrance, and the interior OEGMA units incorporated by the statistical
copolymerization promote intracellular drug release by facilitating
the permeation of GSH and H<sup>+</sup> for the cleavage of the reduction-responsive
disulfide bond and pH-liable carbonate link as well as weakening the
hydrophobic encapsulation of drug molecules. The delivery efficacy
of the target hyperbranched block-statistical copolymer-based prodrug
was evaluated in terms of <i>in vitro</i> drug release and
cytotoxicity studies, which confirms both acidic pH and reduction-triggered
drug release for inhibiting proliferation of HeLa cells. Interestingly,
the simultaneous application of both acidic pH and GSH triggers promoted
significantly the cleavage and release of CPT compared to the exertion
of single trigger. This study thus developed a facile approach toward
hyperbranched polymer-based prodrugs with high therapeutic efficacy
for anticancer drug delivery