Abstract:Superhydrophobic
polybenzoxazine (PBZ)/TiO2 coatings
with reversible wettability were fabricated by blending eugenol/siloxane-based
benzoxazine (E-aptmds) with TiO2 nanoparticles through
spin coating and thermal curing processes. The resulting coatings
could switch between superhydrophobicity and superhydrophilicity through
alternate ultraviolet (UV) irradiation and heating treatment cycles.
The PBZ/TiO2 coating-modified stainless steel mesh (PBZ/TiO2 mesh) had ultra-high oil/water separation fluxes of over
54… Show more
“…The peak at 1660 cm –1 was generated by the stretching vibration of the benzene ring backbone . The spectrum showed a broad peak near 620 cm –1 , which was considered a sign of the presence of Ti–O . It can be speculated that Ti–O is the bridge connecting TA molecules.…”
Section: Results
and Discussionmentioning
confidence: 98%
“…26 The spectrum showed a broad peak near 620 cm −1 , which was considered a sign of the presence of Ti−O. 37 It can be speculated that Ti−O is the bridge connecting TA molecules.…”
It is significant to explore green,
convenient, and widely applicable
superhydrophilic coatings. This study proposes a strategy of using
covalent cross-linking of tannic acid and tetrabutyl titanate to prepare
a superhydrophilic coating, which can be simply applied on the porous
substrate surface by vacuum filtration and immersion without additional
binders. The surfaces modified by coatings get intriguing superhydrophilicity
and underwater superoleophobicity due to the synergistic effect of
the high roughness and hydrophilic polyphenols. A permeation flux
of up to 5663.57 L m–2 h–1 bar–1 with a filtrate total organic carbon content of only
41.95 ppm is obtained under 0.1 bar. The modified membranes also exhibit
efficient purification of dye solutions and mixed wastewaters, with
absorbance reductions of up to 99.4%. In addition, stability tests
prove the coatings to be acid- and alkali-resistant as well as mechanically
robust. The surface modification method developed in this work can
be easily extended to various materials for industrial wastewater
treatment.
“…The peak at 1660 cm –1 was generated by the stretching vibration of the benzene ring backbone . The spectrum showed a broad peak near 620 cm –1 , which was considered a sign of the presence of Ti–O . It can be speculated that Ti–O is the bridge connecting TA molecules.…”
Section: Results
and Discussionmentioning
confidence: 98%
“…26 The spectrum showed a broad peak near 620 cm −1 , which was considered a sign of the presence of Ti−O. 37 It can be speculated that Ti−O is the bridge connecting TA molecules.…”
It is significant to explore green,
convenient, and widely applicable
superhydrophilic coatings. This study proposes a strategy of using
covalent cross-linking of tannic acid and tetrabutyl titanate to prepare
a superhydrophilic coating, which can be simply applied on the porous
substrate surface by vacuum filtration and immersion without additional
binders. The surfaces modified by coatings get intriguing superhydrophilicity
and underwater superoleophobicity due to the synergistic effect of
the high roughness and hydrophilic polyphenols. A permeation flux
of up to 5663.57 L m–2 h–1 bar–1 with a filtrate total organic carbon content of only
41.95 ppm is obtained under 0.1 bar. The modified membranes also exhibit
efficient purification of dye solutions and mixed wastewaters, with
absorbance reductions of up to 99.4%. In addition, stability tests
prove the coatings to be acid- and alkali-resistant as well as mechanically
robust. The surface modification method developed in this work can
be easily extended to various materials for industrial wastewater
treatment.
“…With 10 wt% nanoTiO 2 , the hydrophobicity of PBZ/TiO 2 nanocomposites were significantly enhanced to WCA = 155 ± 3°. 55 This type of rough structured coatings may find applications in the fields of superhydrophobic coatings.Figure 15.Water contact angle of neat PBZ and nTiO 2 /PBZ hybrid nanocomposites.…”
A new class of nanotitania reinforced polybenzoxazine (nTiO2/PBZ) hybrid nanocomposites was synthesized using newly designed phthalide cardo chain extended imine skeletal linked maleimido end capped polybenzoxazine (PHM-PBZ) and nTiO2 through in-situ sol-gel method. The formation of hybrid nanocomposites was confirmed by NMR and FT-IR spectra. The structurally stable nTiO2 present in the nTiO2/PBZ hybrids accounted their exceptional thermal stability and good char yield. The restricted motion of flexible polymeric chain resulted from the inclusion of nTiO2 in the PBZ system increased the glass transition temperature ( T g) to a higher percentage than that of neat PBZ system. With the successive enhancement in the incorporation of nTiO2, the synthesized nanocomposites exhibited better thermal stability, higher flame retardancy and lesser water absorption behaviour than the of neat PBZ. The sequential increments in the loading level of nTiO2 onto the PBZ matrices caused the lower value of dielectric constant than that of neat PBZ. The homogeneity and successful dispersion of the nTiO2 fillers in the PBZ matrix were ascertained from the strong fluorescent emissions observed in the wavelength range of 300–550 nm through optical studies. Scanning electron microscope and transmission electron microscopic micrographs evidenced the successful incorporation of nTiO2 as can be seen from the different morphology at the nanoscale level in the PBZ matrix. This kind of structurally designed nTiO2/PBZ nanocomposites may find multifaceted applications in the form of adhesives, encapsulants, matrices and sealants and in the fields of automobile and microelectronics applications for better performance and longevity.
“…PBzs have recently gained considerable interest because of their outstanding potential of exhibiting the excellent properties of traditional phenolic resins, which make them attractive alternatives to a wide range of end-use applications. Aerospace and naval composites, − automotive frames and components, , composite pipes for gas or oil, , circuit boards, , aerogels, , self-healing materials, − coatings and corrosion protection, − and paints , are among these end-use applications. PBzs possess highly attractive features such as high glass transition temperature ( T g ), , low water absorption, near zero shrinkage upon polymerization, , high char yield, , fast evolution of mechanical properties with the conversion, , similar and even lower costs than epoxy and bismaleimides resins, and excellent dielectric properties. , These outstanding properties and intrinsically rich molecular design flexibility allowing good compatibility with other structures have rendered PBz an important contender to epoxy and traditional phenolic resins in the composite industry.…”
In this study, we report the successful synthesis of
a novel Al-based
MOF/polybenzoxazine nanocomposite by a facile and green approach via
thermally induced ring-opening polymerization (ROP). Structural and
thermal characterization of the synthesized nanocomposite was accomplished
using FTIR, XRD, BET and TGA, and DSC techniques, respectively. The
Al-MOF showed catalytic activity in ROP and good thermal stability
compared to the non-catalyzed system. The catalytic impact of MIL-53-Al
on the ROP of benzoxazine is revealed by calorimetry at both isothermal
and dynamic modes in detail. The Starink isoconversional analysis
revealed that the MOF-catalyzed ROP proceeded faster at the reaction’s
early stages, typically at α ≤ 40%. The Friedman method
was also applied to the experimental data to get more insights into
the mechanisms of the ROP reaction. Results indicated that both systems
follow a conversion-dependent mechanism for cationic ROP of the benzoxazine.
Although the complexity of the ROP of benzoxazines reduces the reliability
of model fitting, the activation energy data were confirmed. Moreover,
it was demonstrated that the reaction mechanism changes from the autocatalytic
to the n-order regime during the reaction. An ROP
mechanism is proposed at which the available AlO4(OH)2 octahedra act as active sites shifting the curing exotherms
to lower temperatures.
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