Colloid and Polymer Science最新文献

Flexible strain sensors need to obtain a stable signal as the target undergoes random and repeated deformation. Therefore, excellent mechanical properties, adhesion properties, and electrical conductivity are essential. In this study, a stretchable, self-adhesive, and conductive ionic hydrogel was designed and synthesized. Zwitterionic hydrogels were synthesized by micellar copolymerization of hydrophobic monomer methacrylate stearic acid (C18) with hydrophilic monomers [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) in the presence of sodium dodecyl sulfate (SDS) surfactant. Compared with traditional chemical cross-linked hydrogels, the elongation at break is increased by 934%. The multi-walled carbon nanotubes (MWCNTs) modified with tannic acid (TA) have good dispersibility and stability, which can be added to the hydrogel as a functional filler to enhance the tensile and conductive properties of the sensor. The hydrogel flexible sensor prepared under the synergistic action of various mechanisms has good mechanical properties, bonding properties, and conductive properties. In addition, due to the inherent antibacterial properties of the raw material, the hydrogel has a bactericidal ratio of up to 99% against E. coli and S. aureus under the premise of good biocompatibility in vitro, which has great potential in the field of monitoring human movement and healthcare.

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The degradation and recycling of waste epoxy resins is an urgent environmental problem, encouraging the use of degradable thermosetting epoxies. In this study, a high-performance thermosetting epoxy resin material that can be easily degraded and recycled was prepared using a low-viscosity and high-activity epoxy monomer, tetrahydrophthalic acid diglycidyl ester. Owing to the breakable ester bond in this epoxy monomer, the thermosetting three-dimensional epoxy cross-linked structure can be rapidly degraded using ethylene glycol at atmospheric pressure. After further depolymerization of the epoxy resin/glycol solution with NaOH, sodium cyclohexene-2-carboxylate was obtained. The sodium salt was acidified, epoxidized, and then re-prepared to obtain the epoxy monomer diglycidyl tetrahydrophthalate. The recycled epoxy monomer possesses the same thermal and mechanical properties as the original epoxy monomer, thus realizing the economic and environmentally friendly degradation and recycling of the thermosetting epoxy resin under mild conditions, and this recycling method is applicable to epoxy systems with ester bonding in the cured material.

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This study focused on the thermal stability and the thermal degradation kinetics of two poly(vinyl ethers), PVEs, with different side groups. The objective was to determine how the nature of the side group affects the thermal properties of these materials. Poly(2–Phthalimide Ethyl Vinyl Ether), PPEVE, was derived via zirconocene–mediated cationic homopolymerization, and poly(2–Amino Ethyl Vinyl Ether), PAEVE, was obtained by hydrazinolysis of PPEVE. The thermal stability was investigated by employing thermogravimetric analysis (TGA) and differential thermogravimetry, DTG, at six different heating rates. The thermal decomposition kinetics data were evaluated using the Ozawa–Flynn–Wall, OFW, and Kissinger–Akahira–Sunose, KAS, “model-free” methods to calculate the activation energies, (Ea), and subsequently the appropriate mathematical model or mechanism to describe the thermal decomposition process for each individual homopolymer.

This work investigates the Maxwell fluid flow in the variable porous space of cone and disc influenced by double diffusion on a variable porous space. In this study, the heat and mass transfer is influenced by the combined effects of Fourier’s and Fick’s laws, leading to heat and mass flux assumptions proposed by Cattaneo-Christov to characterize these transfer phenomena. The modeled equations have been converted to dimensionless form by using a suitable set of appropriate variables. This set of dimensionless equations was then solved by using artificial neural networks (ANNs). For this, initially, HAM (homotopy analysis method) has been used for the evaluation of modeled equations, and then, to analyze the dynamics of flow, Levenberg Marquardt Scheme through Neural Network Algorithm (LMS-NNA) has been employed. The optimal performance of the fluid model is observed at the epoch 10, 08, 427, 164, 203, 146, 101, 130, 255, 298, 166, and 222. The proximity to unity is a pivotal observation in this work that has been signifying a high degree of precision in the LMS-NNA design for the proposed model. The porosity factor has opposed the primary velocity profiles and has supported the secondary velocity profiles. Moreover, primary velocity profiles have declined with growth in Maxwell factor while secondary velocity panels have retarded by the upsurge in the retardation time factor. Thermal distribution has been supported by progression in thermophoresis and Brownian motion factors and has been opposed by escalation in the Prandtl number. Concentration distribution has augmented with the upsurge in thermophoresis factor and has declined with the escalation in factor, Schmidt number, and concentration relaxation time factor. It has been also observed in this work that the variable porous space controls the fluid flow and maintains the stability of Maxwell fluid flow between the cone and disc apparatus. The maximum error for testing, training, and validation of the proposed model is achieved for all 12 cases and discussed numerically in tabular form.

A general expression is derived for the Laplace transform of the time dependent transient electrophoretic mobility of spherical colloidal particles in a multi-particle suspension when a step external electric field is suddenly applied to the colloidal suspension. From the general mobility expression, we obtain a simple closed form expression for the Laplace transform of the time-dependent transient electrophoretic mobility of weakly charged spherical colloidal particles in an electrolyte solution. The obtained Laplace transform of the transient electrophoretic mobility of particles does not involve numerical integrations so that its inverse Laplace transform is easily obtained using calculation software.

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Time-dependent transient Henry function for spherical colloidal particles in a multi-particle suspension.

This study introduces a novel method for the rapid and efficient detection of paracetamol, leveraging a colorimetric sensing mechanism predicated on the utilization of TMB-MnO₂ nanosheets. The interaction of paracetamol with MnO₂ is characterized by a selective reaction mechanism, leading to the reduction of MnO₂ to Mn²⁺ ions and consequent attenuation of the oxidase-mimetic activity of MnO₂. The developed colorimetric sensor exhibits a linear detection range for paracetamol extending from 5 × 10⁻⁴ to 10⁻² M, with a lower detection limit quantified at 5.24 × 10⁻⁷ M. Empirical assessments conducted to ascertain the influence of potential interferents prevalent in actual samples revealed a negligible impact on the colorimetric sensor. Furthermore, the application of this sensor system to real-world samples demonstrated its capability to detect paracetamol with a notable recovery rate and a relative standard deviation of < 6.65%. This approach manifests significant promise for the efficacious detection of paracetamol in various sample matrices.

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In the present study, the MnO₂ adsorbents with a crystal structure, the components of approximately 59% Mn and 40% O, and the specific linkages of -OH and O-Mn-O were characterized by the techniques XDR, EDX, and FI-IR, respectively. Especially, the individual and simultaneous adsorptions of chromium, Cr(VI), and an antibiotic, CFX, on the manganese dioxide (MnO₂) material were systematically investigated. Compared with the individual adsorption, the CFX adsorption efficiency was significantly reduced in the Cr(VI) presence due to the Cr(VI)-CFX complexation formed by the Cr₂O₇²⁻ or HCrO₄⁻-NH₂⁺ electrostatic attractions. The optimal experimental conditions for the Cr(VI)-CFX simultaneous adsorption were found to be pH 6, 1 mM NaCl, 60 min contact time, and 50 mg.mL⁻¹ MnO₂ dosage. The maximum adsorption efficiencies of the Cr(VI) and the CFX on the MnO₂ were achieved at 98.1 and 87.5%, respectively. The maximum adsorption capacities of the Cr(VI) and CFX were correspondingly extrapolated to be 144.5 and 100.1 mg.g⁻¹ by the Langmuir adsorption model. The Cr(VI)-CFX simultaneous adsorption was adequately described by the Freundlich isotherm and the pseudo-second kinetic models. The chemisorption of Cr(VI)-CFX governed the simultaneous adsorption with the formation of multiple adsorbed layers.

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High internal phase emulsions (HIPEs) are commonly stabilized by a large amount of surfactants that should be removed after the polymerization of the continuous phase, and the resulting polyHIPEs from W/O HIPEs are usually brittle and chalky. Herein we report on an amphiphilic polymerizable polyurethane (PPU) macromolecular surfactant synthesized by polyaddition reaction of diisocyanates and polyols, which can well stabilize up to 88% internal phase volume of W/O HIPE with a content of only 5 wt% based the oil phase. Compared with the HIPEs stabilized by traditional surfactant Span 80, HIPEs stabilized by PPU at either room temperature or 70 °C are much more stable owing to the increased viscosity which can inhibit droplet coalescence. Moreover, the resulting polyHIPEs not only have several times higher mechanical properties than those stabilized by Span 80 but also have higher elasticity. The effects of concentration of PPU on the morphology and mechanical properties of the resulting polyHIPEs were investigated. It was found that with the increase of PPU content, the average void and window sizes decreased, while the compression strength increased. Cyclic compression tests were performed to examine reversible compressibility and durability of these polyHIPEs.

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The polymerizable polyurethane macromolecular surfactant (PPU) synthesized through the polyaddition reaction of diisocyanates and polyols can solely stabilize high internal phase emulsions (HIPEs), and highly interconnected macroporous polymer produced by the polymerization of HIPE stabilized with PPU, known as polyHIPE, can withstand large deformation compression with no visible cracks.

This study investigated the use of cellulose nanocrystals (CNC)/chitosan (Chit) polyelectrolyte complex as a stabilizing agent for Pickering emulsions. We demonstrated that chitosan reduces the surface charge of CNC improving the emulsification process. An optimal stabilizing complex containing 1% chitosan results in emulsions with minimal zeta potential (3.2 ± 0.3 mV), droplet size (2.8 ± 0.8 μm), and creaming index (19.8 ± 1.0%) values, along with high stability during storage, a change in pH, and high centrifugal forces (up to 2000 g). The study also showed that the maximum neutralized surface charge of the CNC in the CNC-Chit complex allows for effective adsorption on the surface of sunflower oil droplets, producing a denser stabilizing layer with a smaller droplet size. Additionally, chitosan addition is linked to improved stability and higher viscosity, with little dependence on ionic strength and temperature. Potentiometric titration revealed that compared with sulfated CNCs, five times less chitosan is needed to neutralize the negative surface charge of acetylated CNC. The wettability of a hydrophilic surface depends on the surface charge of the complex, and the wettability and adhesion performance increase with increasing chitosan content. Additionally, we showed that tuning the stabilizer composition can change the bioaccessibility of lipophilic compounds during oral administration.

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