This work investigated the redispersion and setting behavior of highly loaded (~ 18 wt.% solids in water) pastes of cellulose nanofibrils (CNFs) with carboxymethyl cellulose (CMC). A single-screw ...extruder was used to continuously process CNF + CMC pastes into cord. The adsorption of CMC onto the CNFs was assessed through zeta potential and titration which revealed a surface charge change of ~ 61% from − 36.8 mV and 0.094 mmol/g COOH for pure CNF to -58.1 mV and 0.166 mmol/g COOH for CNF + CMC with a CMC degree of substitution of 0.9. Dried CNFs with adsorbed CMC was found to be fully redispersible in water and re-extruded back into a cord without any difficulties. On the other hand, chemical treatment with hydrochloric acid, a carbodiimide crosslinker, or two wet strength enhancers (polyamide epichlorohydrin and polyamine epichlorohydrin) completely suppressed the dispersibility previously observed for dried-untreated CNF + CMC. Turbidity was used to quantify the level of redispersion or setting achieved by the untreated and chemically treated CNF + CMC in both water and a strong alkaline solution (0.1 M NaOH). Depending on the chemical treatment used, FTIR analysis revealed the presence of ester, N-acyl urea, and anhydride absorption bands which were attributed to newly formed linkages between CNFs, possibly explaining the suppressed redispersion behavior. Water uptake of the differently treated and dried CNF + CMC materials agreed with both turbidity and FTIR results.
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Despite the fact that soybean-based adhesives offer huge advantages such as sustainability and being eco-friendly, their wider application in wood composites has been severely restricted by the poor ...resistance towards wet environments and mildew. In this study, a soybean-based adhesive with excellent hygrothermal and enhanced mildew resistance was developed by optimizing the synthesis of a polyamidoamine–epichlorohydrin (PAE) resin with varying epichlorohydrin (ECH) content and applying formic acid as a terminating agent. FTIR, NMR analyses and plywood evaluation indicated that the ECH content had a significant effect on the hygrothermal resistance of the PAE-modified soybean adhesive. This is attributed to the greater number of azetidine groups resulting from higher ECH content, which effectively crosslinked the soybean meal to form compact networks. However, owing to the more powerful mildew inhibition of formic acid than sulfuric acid and ECH-derived organochlorine, higher ECH content also led to a higher amount of organochlorine in the PAE resin but required less formic acid to terminate PAE polymerization, causing reduced mildew resistance of the soybean adhesive. The PAE resin synthesized with 50% ECH was optimum for formulating a soybean adhesive for wood composites, which showed superior hygrothermal and mildew resistance compared to commercial adhesives.
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•C3G-β-CD-EP-CMC nanoparticles possessed a preferable particle size with good disperse and homogeneous morphology.•Nanoparticles formation of grafting of C3G to β-CD-EP-CMC could ...significantly improve the stability of C3G to against thermal or light degradation.•Expanded the knowledge of the application of β-CD-EP-CMC as a novel wall materials for encapsulation.•Extending the application of C3G in nutraceutical with bioactive enhancement.
Cyanidin-3-glucoside (C3G), an anthocyanin constituent of fruits and vegetables. It has been proven to possess numerous health benefits with no side effects. However, the poor stability of C3G is an intractable property that limits its application. Hence, the aim of this study is to improve the stability of C3G through the formation of well dispersed nanoparticles. In this study, C3G loaded β-CD-EP-CMC nanoparticles exhibited nearly spherical with good disperse and homogeneous morphology. Results also indicated that the nanoparticles formation of grafting of C3G to β-CD-EP-CMC could significantly improve the stability of C3G to against thermal or light degradation. Collectively, current results strongly aligned with the prospective purpose that the grafting of C3G to β-CD-EP-CMC nanoparticles could be treated as an effective approach for improving the stability. This study opens a new avenue for the utilization and development of novel wall materials β-CD-EP-CMC in C3G associated nutraceutical.
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•A new catalyst based on polyoxotungstophosphates was synthesized.•It showed excellent catalytic performance for the epoxidation of allyl chloride.•The catalytic mechanism was proved ...by FT-IR and 31P NMR spectroscopy.•The interface reaction is the rate-controlling step.•The interfacial properties of the catalyst were studied.
The preparation of epoxy compounds by catalytic oxidation with hydrogen peroxide, an environmentally friendly oxidant, is beneficial to reducing pollutants. A new temperature-controlled phase transfer catalyst, (C18H37)2(CH3)2N3{PO4W(O)(O2)24}, was developed for the catalytic epoxidation of allyl chloride with H2O2. Allyl chloride could be epoxidized to epichlorohydrin (ECH) in 97.1% conversion and more than 99% selectivity with equimolar H2O2 and as-prepared catalyst. The catalyst could be precipitated from the solution after reaction by cooling to 10 °C and it was easily recycled five times without significant loss of activity. The catalytic mechanism was proved by FT-IR and 31P NMR spectrum. The constant interface cell device was employed for the kinetic study, and the results indicated that the interface reaction was the control step of the reaction process. The prepared catalyst exhibited obvious interfacial activity and aggregated at the interface.
In this paper, modified starch nanocrystals (SNCs) are prepared successfully by grafting the epichlorohydrin‐dimethylamine copolymer (PA) onto oxidized starch nanocrystals (OSNCs). The material is ...used as an adsorbent to deal with the methyl blue (MB) dye. The OSNCs‐PA is characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and Scanning electron microscopy. The zeta potential of OSNCs‐5.0%PA is +46.6 mV, which has a good adsorption performance for MB. In the adsorption process, the effects of adsorption time, pH, and initial MB concentration on the adsorption capacity are studied with the different OSNCs‐PA, and the adsorption kinetics and adsorption isothermal curves are also fitted. The results show that the maximum adsorption capacity of OSNCs‐0.5%PA, OSNCs‐3.0%PA, OSNCs‐5.0%PA on MB could reach 142.86, 166.67, and 169.49 mg g−1, respectively. The adsorption of OSNCs‐PA for MB conform to the second‐order kinetics and the Langmuir adsorption isotherm.
The authors present a facile method for the preparation of modified starch nanocrystals by grafting epichlorohydrin‐dimethylamine copolymer (PA) onto oxidized starch nanocrystals. It has a good adsorption performance for methyl blue dye. The maximum adsorption capacity of OSNCs‐0.5%PA, OSNCs‐3.0%PA, OSNCs‐5.0%PA on MB can reach 142.86, 166.67, and 169.49 mg g−1, respectively.
Enantioselective hydrolysis of epoxides by epoxide hydrolase (EH) is one of the most attractive approaches for the synthesis of chiral epoxides. So far, attempts to develop an efficient epoxide ...hydrolase -mediated biotransformation have been limited by either the low activity or insufficient enantioselectivity of epoxide hydrolase. In this study, iterative saturation mutagenesis (ISM) of epoxide hydrolase from
Agrobacterium radiobacter
AD1 (ArEH) was performed for efficient production of (
R
)-epichlorohydrin. Six amino acid residues, I108, A110, D131, I133, T247, and G245, were selected for site saturation mutagenesis, and a sequential combination of positive mutants using ISM was constructed. Targeted mutagenesis generated five mutants (T247K, I108L, D131S, T247K/I108L, and T247K/I108L/D131S) with improved activity and enantioselectivity. Kinetics analysis showed that the best mutant, T247K/I108L/D131S, exhibited a 4.5-fold higher catalytic efficiency (
k
cat
/
K
m
) value and a 2.1-fold higher enantioselectivity (
E
value) towards epichlorohydrin than the wild-type (WT) enzyme. Molecular docking computations support the source of notably improved enantioselectivity. In addition, the triple mutant also displayed a significantly enhanced thermostability, with > 8-fold longer half-life at 50 °C than WT. A gram-scale kinetic resolution of (
R
,
S
)-epichlorohydrin was performed using T247K/I108L/D131S mutant as biocatalyst, affording a (
R
)-epichlorohydrin yield of 40.2% (> 99.9% enantiomeric excess) and an average productivity of 1410 g L
−1
d
−1
. The engineered T247K/I108L/D131S variant is a promising biocatalyst for the enzymatic synthesis of (
R
)-epichlorohydrin.
Curcumin (Cur) is an anti-inflammatory polyphenol that can be complexed with polymeric cyclodextrin (CD) to improve solubility and bioavailability. The aim of the present work was to prepare a CurCD ...hydrogel to treat inflammatory skin conditions. Epichlorohydrin-β-CD (EpiβCD) was used as polymeric CD. To characterize the binary system, solid-state and in-solution studies were performed. Afterwards, an experimental design was performed to optimize the hydrogel system. Finally, the CurEpiβCD hydrogel system was tested for anti-inflammatory activity using a HaCat psoriasis cell model. Co-grinded Cur/EpiβCD binary system showed a strong interaction and Curcumin solubility was much improved. Its combination with Pluronic
F-127/hyaluronate hydrogel demonstrated an improvement in release rate and Curcumin permeation. After testing its anti-inflammatory activity, the system showed a significant reduction in IL-6 levels. Hydrogel-containing CurEpiβCD complex is a great alternative to treat topical inflammatory diseases.
In this study, chitosan (CTS) was crosslinked with both epichlorohydrin (ECH) and triphosphate (TPP), by covalent and ionic crosslinking, respectively. The resulting new CTS–ECH–TPP adsorbent was ...characterized by CHN analysis, EDS, FTIR spectroscopy, TGA and DSC, and the adsorption and desorption of Cu(II), Cd(II) and Pb(II) ions in aqueous solution were investigated. Potentiometric studies were also performed and revealed three titratable protons for each p
K
a value of 5.14, 6.76 and 9.08. The results obtained showed that the optimum pH values for adsorption were 6.0 for Cu(II), 7.0 for Cd(II) and 5.0 for Pb(II). The kinetics study demonstrated that the adsorption process proceeded according to the pseudo-second-order model. Three isotherm models (Langmuir, Freundlich and Dubinin-Radushkevich) were employed in the analysis of the adsorption equilibrium data. The Langmuir model resulted in the best fit and the new adsorbent had maximum adsorption capacities for Cu(II), Cd(II) and Pb(II) ions of 130.72, 83.75 and 166.94
mg
g
−1, respectively. Desorption studies revealed that HNO
3 and HCl were the best eluents for desorption of Cu(II), Cd(II) and Pb(II) ions from the crosslinked chitosan.
In this work, new ultrastretchable and super-elastic hydrophilic thermoplastic elastomeric (TPEs) materials were developed for the first time from the thermoplastic polyurethane (TPU) and ...epichlorohydrin-ethylene oxide-allyl glycidyl ether (GECO) rubber using straightforward melt-blending and dynamic vulcanization approaches, which allows the creation of tailorable hydrophilic TPE materials. The resulting materials can absorb up to ∼80% water within 4 h. The absorbed water convert itself into hexagonal ice crystals in the TPE matrix which was directly evident from differential scanning calorimetry and cryo-transmittance electron microscopy. The phase components of developed TPE were found to be interactive which was analysed from the torque and loss tangent values. Interaction was further enhanced after dynamic vulcanization which was predicted from the rheological Palierne model. Interestingly, interfacial tension between the TPU and GECO was significantly reduced after dynamic vulcanization which suggested stronger inter-domain interaction between the phase components. It was revealed that the resulting TPE possess droplet-matrix phase morphological structure which was supported from the theoretical Kerner model prediction. Surprisingly, resulting materials showed extraordinary elastomeric properties than that of TPEs reported earlier, such as very high strain at break (∼800–1000%) and lowest tension set (∼2–6%) which enables the creation of ultrastretchable and super-elastic materials.
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•A new kind of ultra-stretchable, superelastic and tailorable hydrophilic TPE was developed.•The developed TPE showed extraordinary elastic properties having high strain at failure (1000%) and low-tension set (∼2%).•The hexagonal ice crystals were formed in the TPE matrix by absorbed water.
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