6 research outputs found
Tailoring surface hydrophilicity of porous electrospun nanofibers to enhance capillary and push-pull effects for moisture wicking
In this article, liquid moisture transport behaviors of dual-layer electrospun nanofibrous mats are reported for the first time. The dual-layer mats consist of a thick layer of hydrophilic polyacrylonitrile (PAN) nanofibers with a thin layer of hydrophobic polystyrene (PS) nanofibers with and without interpenetrating nanopores, respectively. The mats are coated with polydopamine (PDOPA) to different extents to tailor the water wettability of the PS layer. It is found that with a large quantity of nanochannels, the porous PS nanofibers exhibit a stronger capillary effect than the solid PS nanofibers. The capillary motion in the porous PS nanofibers can be further enhanced by slight surface modification with PDOPA while retaining the large hydrophobicity difference between the two layers, inducing a strong push–pull effect to transport water from the PS to the PAN layer
Tailoring Surface Hydrophilicity of Porous Electrospun Nanofibers to Enhance Capillary and Push–Pull Effects for Moisture Wicking
In
this article, liquid moisture transport behaviors of dual-layer electrospun
nanofibrous mats are reported for the first time. The dual-layer mats
consist of a thick layer of hydrophilic polyacrylonitrile (PAN) nanofibers
with a thin layer of hydrophobic polystyrene (PS) nanofibers with
and without interpenetrating nanopores, respectively. The mats are
coated with polydopamine (PDOPA) to different extents to tailor the
water wettability of the PS layer. It is found that with a large quantity
of nanochannels, the porous PS nanofibers exhibit a stronger capillary
effect than the solid PS nanofibers. The capillary motion in the porous
PS nanofibers can be further enhanced by slight surface modification
with PDOPA while retaining the large hydrophobicity difference between
the two layers, inducing a strong push–pull effect to transport
water from the PS to the PAN layer
Thin MoS<sub>2</sub> Nanoflakes Encapsulated in Carbon Nanofibers as High-Performance Anodes for Lithium-Ion Batteries
In this work, highly flexible MoS<sub>2</sub>-based lithium-ion battery anodes composed of disordered thin
MoS<sub>2</sub> nanoflakes encapsulated in amorphous carbon nanofibrous
mats were fabricated for the first time through hydrothermal synthesis
of graphene-like MoS<sub>2</sub>, followed by electrospinning and
carbonization. X-ray diffraction as well as scanning and transmission
electron microscopic studies show that the as-synthesized MoS<sub>2</sub> nanoflakes have a thickness of about 5 nm with an expanded
interlayer spacing, and their structure and morphology are well-retained
after the electrospinning and carbonization. At relatively low MoS<sub>2</sub> contents, the nanoflakes are dispersed and well-embedded
in the carbon nanofibers. Consequently, excellent electrochemical
performance, including good cyclability and high rate capacity, was
achieved with the hybrid nanofibrous mat at the MoS<sub>2</sub> content
of 47%, which may be attributed to the fine thickness and multilayered
structure of the MoS<sub>2</sub> sheets with an expanded interlayer
spacing, the good charge conduction provided by the high-aspect-ratio
carbon nanofibers, and the robustness of the nanofibrous mat
Simultaneous Enhancements of UV Resistance and Mechanical Properties of Polypropylene by Incorporation of Dopamine-Modified Clay
Inspired by the radical scavenging function of melanin-like
materials and versatile adhesive ability of mussel-adhesion proteins,
dopamine-modified clay (D-clay) was successfully incorporated into
polypropylene (PP) using an amine-terminated PP oligomer as the compatibilizer.
Although the PP/D-clay nanocomposites exhibit intercalated morphology,
the incorporation of D-clay greatly improves the thermo-oxidative
stability and UV resistance of PP owing to the strong radical scavenging
ability of polydopamine (PDA) and large contact area between PP and
the PDA coating on clay mineral. Moreover, the reinforcement effect
brought by D-clay is fairly significant at very low clay loadings
probably owing to the strong interfacial interactions between the
layered silicates and the compatibilizer as well as that between the
compatibilizer and the PP matrix. The work demonstrates that D-clay
is a type of promising nanofiller for thermoplastics used for outdoor
applications since it stabilizes and reinforces the polymers simultaneously
Complexes of Polydopamine-Modified Clay and Ferric Ions as the Framework for Pollutant-Absorbing Supramolecular Hydrogels
Clay-based functional hydrogels were facilely prepared
via a bioinspired
approach. Montmorillonite (clay) was exfoliated into single layers
in water and then coated with a thin layer of polydopamine (PDOPA)
via in situ polymerization of dopamine under basic aqueous conditions.
When a small amount of ferric salt was added into aqueous suspensions
of the polydopamine-coated clay (D-clay), D-clay and Fe<sup>3+</sup> ions could rapidly self-assemble into three-dimensional networks
through the formation of coordination bonds. Consequently, supramolecular
hydrogels were formed at very low D-clay contents. Rheological measurements
show that the D-clay/Fe<sup>3+</sup> hydrogels exhibit fairly elastic
response in low stain range, and have self-healing capability upon
removal of applied large stress. More importantly, the hydrogels can
be used as adsorbents to effectively remove Rhodamine 6G (Rh6G), an
organic pollutant, from water. UV–vis absorption spectra of
the Rh6G-loaded hydrogels show bands related to π–π
stacking interactions between the aromatic moieties of PDOPA and Rh6G,
confirming the formation of PDOPA/Rh6G complex on the surface of D-clay
Reinforcement of Polyether Polyurethane with Dopamine-Modified Clay: The Role of Interfacial Hydrogen Bonding
Dopamine-modified clay (D-clay) was successfully dispersed
into
polyether polyurethane (PU) by solvent blending. It is found that
the incorporation of D-clay into PU gives rise to significant improvements
in mechanical properties, including initial modulus, tensile strength,
and ultimate elongation, at a very low clay loading. The large reinforcement
could be attributed to the hydrogen bonds between the hard segments
of PU and stiff D-clay layers that lead to more effective interfacial
stress transfer between the polymer and D-clay. Besides, the interactions
between D-clay and PU are also stronger than those between Cloisite
30B organoclay and the PU chains. Consequently, at a similar clay
loading, the PU/D-clay nanocomposite has much higher storage modulus
than the PU/organoclay nanocomposite at elevated temperatures