Langmuir最新文献

In heritage conservation, bronze artifacts are highly valued for their unique historical and cultural significance. However, due to the complex environmental factors and the long erosion of time, many bronze artifacts commonly face more severe rust issues, directly leading to fragility and even damage. Traditional rust removal methods often failed to effectively eliminate corrosion of fragile bronze artifacts and may cause irreversible damage, particularly for the delicate bronze artifacts with complicated surfaces. Therefore, there is an urgent need to explore milder and more efficient rust removal techniques for fragile bronze artifacts. This work reports a composite hydrogel film composed of poly(vinyl alcohol) (PVA) hydrogel and the chelating agent ethylenediaminetetraacetic acid (EDTA) based on a solvent-exchange method, which is further applied to remove copper rust from fragile bronze antiquities via surface attachment, hydrogel film formation, and the peel off process. EDTA reacts with metal oxides during the hydrogel film formation process. The copper rust was then removed from the surface of the artifact along with the hydrogel film. The PVA composite hydrogel film is further peeled off from the surface of fragile bronze antiquities due to its good toughness, effectively removing copper rust. The fabricated PVA composite hydrogel film was tested to clean a fragile bronze artifact excavated from Shaanxi Province in China, which can remove ∼90% of the copper rust from the surface. This indicates the effectiveness and feasibility of the PVA-based hydrogel film in the restoration and protection of fragile bronze artifacts.

Although methane-dense storage is anticipated in wet nanoporous materials using the synergy of adsorption and hydration (the so-called adsorption-hydration natural gas, AHNG), the understanding of this technology is still insufficient, which limits its large-scale application. Here, new insights into the AHNG technology are presented, including new findings, phenomena, problems, and solutions, which are helpful to improve the understanding of this technology, enhance methane storage density, and pave the way for its application. Both synergy and antagonism between adsorption and hydration were observed; the synergy increases methane storage capacity, while the antagonism weakens the adsorption and hydration efficiency. In addition, two special phenomena were discussed, which have never been noticed by the hydrate community, and artificial intelligence was thought to provide an effective method for material design, while a storage cell was suggested to improve inner mass transfer of AHNG storage tanks.

Flexible sensors are widely applied in the fields of electronic skins and wearable devices, yet it is still a big challenge to effectively prolong the lifespan of the damaged sensors and reduce environmental pollution caused by discarded sensors after updating and upgrading. Herein, we proposed a self-healing, degradable, and biobased polyurethane elastomer for high-performance flexible pressure sensors. The elastomer synthesized using fatty diamine as a chain extender possessed a high tensile strength of 13.25 MPa and an elongation at break of 830%, and the self-healing efficiency reached up to 109.2%. Additionally, the elastomer could be fully degraded within 7 days in a 1 mol L^-1 NaOH solution with the assistance of ethanol. The elastomer-based pressure sensor with a hump-like microstructure was fabricated with reduced graphene oxide as the conductive material via a simple template method. The sensor showed a high sensitivity of 9.448 kPa^-1, a large sensing range of 0-300 kPa, a short response/recovery time of 40/80 ms, and a good sensing stability of 14,000 cycles. Moreover, the sensor was utilized to monitor different human motions, including muscle contraction, joint bending, swallowing, voice recognition, and pulse beat. Importantly, even after being severely damaged, the sensor was able to recover its function in detecting human motions. The findings of this research provide a strategy for the sustainable development of environmentally friendly and functional elastomers and flexible sensors.

Accurate determination of the zeta potential in colloidal dispersions often requires consideration of the relaxation effect, which is associated with the polarization of the electrical double layer and the surface conductivity. In this study, we pursue a new approach that combines conductivity measurements of the dispersion and dispersion medium with the electroacoustic and electrophoretic zeta potential determination. The conductivity data are analyzed with the Maxwell-Wagner-O'Konski theory, providing the Dukhin number. Zeta potentials of highly concentrated polymer dispersions were determined using the colloid vibration current (CVI) method and compared with those obtained by electrophoretic light scattering (ELS) in diluted dispersions. In both cases, the relaxation effect was now taken into account on the basis of the experimentally determined Dukhin number. The evaluation of the Dukhin numbers revealed significant surface conductivity for all investigated polymer dispersions. In addition, it was often found that not only the diffuse layer but also the stagnant layer contributes considerably to the surface conductivity. Proper consideration of both effects is essential for the reliable determination of the zeta potential, as otherwise inconsistencies can be observed in the evaluated data. Moreover, we have validated for the first time that the advanced CVI theory takes the effect of surface conductivity properly into account for a wide range of particle volume fractions. These values agree well with those obtained by the ELS method using the Dukhin-Semenikhin theory or a modified theory of Ohshima, Healy, and White. This study thus shows that the Dukhin number can serve as a key parameter to reliably connect conductivity and electrophoretic and electroacoustic experiments.

This study is focused on the application of a dual surface coating on poly(dimethylsiloxane) (PDMS) flow chambers, which aims to inhibit the contact activation pathway of coagulation. Polyethylene glycol (PEG) is a commonly used biocompatible molecule due to its hydrophilic nature and capacity to reduce protein adsorption. Corn trypsin inhibitor (CTI) is a selective inhibitor of Factor XII, which is the initial factor responsible for activating the intrinsic pathway of coagulation. By sequentially applying these two coatings to PDMS substrates, we expect the PEG-CTI coating to decrease blood clot formation and reduce fibrinogen deposition on surfaces compared to uncoated surfaces. Our results indicate that the PEG-CTI coating was successful in significantly reducing both cell adsorption and fibrinogen deposition to the surfaces of PDMS flow chambers. This study is a step toward applying PEG-CTI surface coatings to PDMS microfluidic artificial lungs, in which the surface interaction between the PDMS lungs and blood is a critical issue that must be mitigated to realize the full potential of this exciting therapeutic tool.

Isononanol, a branched aliphatic alcohol, is derived from isobutylene upgradation, encompassing dimerization and hydroformylation. Branched surfactants exhibit lower surface tension, superior wettability, and rapid defoaming compared to linear surfactants. Isononanol (C₉-OH) with abundant methyl branching can serve as a hydrophobic tail of branched surfactants, suffering from insufficient lipophilicity due to its short effective chain length. This paper proposes a strategy to extend the hydrophobic tail by grafting one propylene oxide (P₁) or butylene oxide (B₁) to increase chain length and branching degree with the aim of synthesizing extended multibranched alcohols C₉P₁-OH and C₉B₁-OH with purities of 95.3 and 97.2%, respectively. Subsequently, a series of extended multibranched alcohol polyether nonionic surfactants (C₉P₁E_n and C₉B₁E_n) were synthesized by ethoxylation, with their structures confirmed by Fourier-transform infrared (FT-IR) and ¹H NMR and their surfactant properties systematically investigated. The findings indicate that C₉P₁E_n and C₉B₁E_n exhibited lower γ_CMC values compared to the isononanol polyether surfactant (C₉E_n), which allows for rapid wetting on a hydrophobic surface, especially C₉B₁E₆ with an initial contact angle of only 54° compared to 80° for C₉E₆. Also remarkable is the rapid defoaming performance, with C₉B₁E₆ having less than 0.1% of the initial foam volume but C₉E₆ having up to 50.1% foam volume after 30 s. These surfactant performances provide significant benefits for the potential application of branched nonionic surfactants in the industrial cleaning field.

Exploiting conductive biobased polymer nanocomposites for electromagnetic interference (EMI) shielding is a rapidly evolving research area. In this study, we systematically fine-tune the nano- and microstructural features of bacterial cellulose (BC) modified with poly(3,4-ethylenedioxythiophene) (PEDOT) for EMI shielding applications. First, to investigate the effect of nanostructure, PEDOT is incorporated into the BC matrix using two methods: chemical vapor polymerization (CVP) and in situ polymerization. The CVP method produces more uniform and denser BC-PEDOT nanocomposites, resulting in cryogels with higher electrical conductivity and total EMI shielding effectiveness (SE_T) (52 ± 2 S/m, 37 dB) compared to those of the in situ polymerized BC-PEDOT cryogels (7 ± 1.5 S/m, 27 dB). The cryogels' microstructure is then adjusted to control the EMI shielding mechanisms by applying different drying methods: freeze-drying, air-drying, and hybrid freeze- and air-drying. Our results indicate that the more energy-efficient air-drying method enhances the reflection-dominant EMI shielding mechanism, with a slight increase in total shielding effectiveness. The drying conditions also affect the final mechanical properties of the samples. Overall, this study demonstrates that BC-PEDOT nanocomposites are excellent candidates for EMI shielding applications.

In order to investigate the essence of CH₄/CO₂ adsorption in coal for CO₂-enhanced coalbed methane recovery (CO₂-ECBM), this study established the coal structure models from the chemical composition and structure information on different rank coals to conduct CH₄ and CO₂ adsorption simulation under different environmental conditions. Thus, the differences and connections between integral heat and isosteric heat of CH₄/CO₂ adsorption in coal and its micro-mechanism were discussed. The results show that as the coal metamorphism degree deepens, the integral heat of CH₄/CO₂ adsorption, similar to adsorption capacity, presents a decreasing first and then increasing trend. While the adsorption equilibrium time of high-rank coal gives a significantly decreasing characteristic with pressure. Then, on the basis of adsorption simulation behavior, it finds that because complex functional groups exist in the coal macromolecular structure, the adsorption capacity shows a different characteristic compared with the experimental results; that is, it decreases with the coal metamorphism degree. Meanwhile, compared to CO₂ adsorption, the isosteric heat of CH₄ adsorption appears to have an obvious downward trend with increasing pressure and then gradually stabilizes. Further, there is always a clear linear relationship between CH₄ adsorption capacity, and isosteric heat for aromatic pores in different rank coals. While for slit pores, both CH₄ and CO₂ molecules exhibit significant parabolic relationships between adsorption capacity and isosteric heat. In addition, on the one hand, except for the obvious chemical adsorption of low-rank coal in the high-pressure stage, affected by pore morphology and size, the isosteric heat of CH₄ or CO₂ adsorption manifests lower values in slit pores and large pore sizes. On the other hand, based on the adsorption systems of similar structural fragments with different functional groups, -OH has been identified as the functional group with the strongest adsorption effect on gas molecules and is also the main functional group causing CO₂ chemical adsorption.

The reuse of hazardous HCl contaminants containing various impurities is a challenging issue in academia and industry. An efficient method for the direct utilization of industrial HCl contaminants has been developed based on the oxychlorination of phenol using hydrogen peroxide as an oxidant. By employing HCl from hydrochloric acid contaminants as a chlorinating agent, 87-94% of HCl was effectively reused for the synthesis of chlorophenols. The process achieved complete conversion of phenol and highly selective oxychlorination of the C-H bonds of phenol at both ortho- and para-positions, particularly forming 2,4-dichlorophenol, in the presence of reaction-promoting additives. Various characterizations indicated that the surfactants promoted the formation of stable aggregates. The reaction primarily occurred at the aggregates interface, with diameters less than 100 nm. These aggregates exert a nanoscale limiting effect on the spatial structure of phenol, resulting in the highly selective formation of 2,4-dichlorophenol during the oxidative chlorination of phenol with HCl. This method demonstrates a highly efficient treatment rate for HCl pollutants containing impurities.