In
recent years, the biomimetic superhydrophobic coatings have
received tremendous attention, owing to their potential in fabricating
self-cleaning surfaces, in environmental applications. Consequently,
extensive research has been devoted to create a superhydrophobic surface
using the oxidized derivatives of CNTs and graphene. Thus, the design
and development of a self-cleaning/superhydrophobic surface with good
biocompatibility are an effective approach to deal with the bacterial
infections related to biomedical devices used in hospitals. In this
context, herein, we have developed the material based on ionic liquid
(IL)-functionalized multiwalled carbon nanotubes (MWCNTs) for hydrophobic
coatings, which was fully characterized with various techniques such
as Fourier transform infrared, powder X-ray diffraction, energy-dispersive
X-ray spectroscopy, and scanning electron microscopy. We have evaluated
the synthesized ILs for their antibacterial potential against the
pathogenic bacterial strains such as Gram-positive (Staphylococcus aureus and methicillin-resistant S. aureus) and Gram-negative (Escherichia
coli) bacterial strains. Further, atomic force and
scanning electron microscopic studies have been performed to investigate
the morphological changes to unravel the mechanism of action, whereas
DNA binding study indicates the binding of IL-1d@MWCNT with DNA (K
a = 2.390 × 104 M–1). Furthermore, the developed material (IL-1d@MWCNT) is coated onto
the surface of polyvinyl chloride (PVC) and evaluated for hydrophobicity
through water contact angle measurements and possesses long-term antibacterial
efficiency against both under-investigating pathogenic strains. For
the biocompatibility assay, the obtained coated PVC material has also
been evaluated for its cytotoxicity, and results reveal no toxicity
against viable cells. These all results are taken together, indicating
that by coating with the developed material IL-1d@MWCNT, a robust
self-sterilizing surface has achieved, which helps in maintaining
a bacteria-free surface.
An experimental investigation is performed to characterize the effect of carbon nanotubes on the average mechanical properties of polyurethane foams. Polyurethane foams are doped with as-grown and oxidized carbon nanotubes at varying carbon nanotube concentrations. It is observed that the inclusion of carbon nanotubes up to a threshold concentration decreases the density of freely expanding polyurethane foams. Uniaxial and cyclic compression testing of foam samples is carried out to study their energy dissipation and rate dependent deformation behavior. While energy dissipation is observed to be higher in neat polyurethane foams, carbon nanotube reinforced foams show better recovery when compressed beyond elastic limit due to their stiffer foam cell walls. It is shown that incorporation of oxidized carbon nanotubes should be preferred over as grown carbon nanotubes to improve flexural, thermal and acoustic response of polyurethane foams. Scanning electron microscopy analysis of compressed samples reveals that cell shearing; cell bending and fracture at nodes are the predominant mode of deformation in all foam samples.
This study aims to develop carbon nanotubes (CNTs) reinforced poly(vinyl alcohol) (PVA) foams as a possible material for stapedial annular ligament (SAL) application. As-grown (AG) and purified CNTs are used as reinforcing fillers for PVA foams. Uniaxial and cyclic compression tests reveal that specific modulus and energy dissipation behavior improve after reinforcing foam with CNTs. A relatively higher improvement in specific modulus is recorded for purified CNTs as they tend to produce stiffer cell walls. Thermogravimetric analysis shows thermal stability improves after addition of CNTs in PVA foams. The 50 wt % degradation temperature is higher for PVA_AG foam in comparison to neat PVA foam. Under dynamic loading storage, modulus is found to be higher for CNT doped foams with higher relative improvement with purified CNTs than AG CNTs. It is shown that reinforcing PVA foams with purified CNTs is a feasible strategy to improve their average mechanical properties and microstructure for SAL application. While the specific elastic modulus of neat PVA foam found to be in range of 0.05-0.06 MPa gcc −1 with almost zero porosity. The addition of CNTs provides a wide range of specific elastic modulus 0.1-1.3 MPa gcc −1 with an average pores size of about 300 μm.
An experimental investigation is carried out to explore the possibility of carbon nanotubes addition and incorporation of polydimethylsiloxane soft interlayer in improving the impact strength and energy-absorbing capability of conventional glass fiber-reinforced plastics. To this end, deformation behavior of glass fiber-reinforced plastics, carbon nanotube-modified glass fiber-reinforced plastics, and glass fiber-reinforced plastics-polydimethylsiloxane sandwich coupons under high strain rate loading are compared using the split-Hopkinson pressure bar testing technique. While neat epoxy is used to process conventional glass fiber-reinforced plastics, the carbon nanotubes-modified glass fiber-reinforced plastics samples are fabricated using 0.5 wt. % carbon nanotube-modified epoxy. The split-Hopkinson pressure bar testing reveals that the addition of carbon nanotubes improves the peak stress and energy-absorbing capacity of the epoxy matrix. The improved impact response of carbon nanotube-modified epoxy translates into enhanced peak stress and energy-absorbing capability of carbon nanotubes-modified glass fiber-reinforced plastics in comparison to conventional glass fiber-reinforced plastics under impact loading. The microscopy analysis of failed composite samples reveals that while glass fiber-reinforced plastics primarily fails at the fiber/epoxy interface, the failure initiates in the epoxy matrix in carbon nanotubes-modified glass fiber-reinforced plastics samples. The impact testing of sandwich samples shows that the insertion of neat and 0.05 wt. % carbon nanotube-modified polydimethylsiloxane interlayer helps to distribute the impact load in a wider domain and thus delays the failure of glass fiber-reinforced plastics sandwich coupons. Moreover, the carbon nanotube-modified polydimethylsiloxane interlayer is better suited to increase the damage resistance and energy-absorbing ability of glass fiber-reinforced plastics. The present study provides a feasible strategy to enhance the failure strength and energy-absorbing capacity of conventional composites using carbon nanotube-modified epoxy and polydimethylsiloxane-based interlayer.
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