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1.
Small ; : e2310092, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38377281

RESUMO

Supported ionic liquid membranes (SILMs), owing to their capacities in harnessing physicochemical properties of ionic liquid for exceptional CO2 solubility, have emerged as a promising platform for CO2 extraction. Despite great achievements, existing SILMs suffer from poor structural and performance stability under high-pressure or long-term operations, significantly limiting their applications. Herein, a one-step and in situ interfacial polymerization strategy is proposed to elaborate a thin, mechanically-robust, and highly-permeable polyamide armor on the SILMs to effectively protect ionic liquid within porous supports, allowing for intensifying the overall stability of SILMs without compromising CO2 separation performance. The armored SILMs have a profound increase of breakthrough pressure by 105% compared to conventional counterparts without armor, and display high and stable operating pressure exceeding that of most SILMs previously reported. It is further demonstrated that the armored SILMs exhibit ultrahigh ideal CO2 /N2 selectivity of about 200 and excellent CO2 permeation of 78 barrers upon over 150 h operation, as opposed to the full failure of CO2 separation performance within 36 h using conventional SILMs. The design concept of armor provides a flexible and additional dimension in developing high-performance and durable SILMs, pushing the practical application of ionic liquids in separation processes.

2.
Small ; : e2310952, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38377230

RESUMO

Salt scaling poses a significant obstacle to the practical implementation of solar-driven evaporation for desalination. Attempts to mitigate scaling by enhancing mass transfer often lead to a compromise in evaporation efficiency due to associated heat loss. In the present work, a novel seesaw evaporator with a Janus structure to harness scaling for periodic self-descaling is reported. The seesaw evaporators are facilely fabricated by delignifying balsa wood and subsequently single-sided spray-coating it with soot and polydimethylsiloxane (PDMS). This unique Janus structure enables the evaporator to float on the brine while ensuring an ample supply of solution for evaporation. During evaporation, salt ions are transported directionally toward the cocked end of the evaporator to form scaling, triggering the seesaw evaporator to flip once a threshold is reached. The accumulated salts re-dissolve back into the solution. By adjusting the tilt angle, the evaporator can achieve an impressive evaporation rate of up to 2.65 kg m-2  h-1 when evaporating an 8 wt.% NaCl solution. Remarkably, these evaporators maintain a stable evaporation rate during prolonged 120 h operation and produce ≈3.93-6.35 L m⁻2 ·day⁻¹ of freshwater from simulated brines when assembled into an evaporation device.

3.
Soft Matter ; 20(8): 1905-1912, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38323340

RESUMO

The spontaneous emulsification for the formation of water-in-oil (W/O) or oil-in-water (O/W) emulsions needs the help of at least one kind of the third component (surfactant or cosolvent) to stabilize the oil-water interface. Herein, with the water/CS2-soluble polymer poly(N,N-diethylacrylamide) (PDEAM) as a surfactant, the spontaneous formation of water-in-PDEAM/CS2 emulsions is reported for the first time. The strong affinity between PDEAM and water or the increase of PDEAM concentration will accelerate the emulsification process with high dispersed phase content. It is demonstrated that the spontaneous emulsification of condensed water droplets into the PDEAM/CS2 solution occurs during the breath figure process, resulting in porous films with two levels of pore sizes (i.e., micron and submicron). The emulsification degree and the amounts of submicron-sized pores increase with PDEAM concentration and solidifying time of the solution. This work brings about incremental interest in spontaneous emulsification that may happen during the breath figure process. The combination of these two simultaneous processes provides us with an option to build hierarchically porous structures with condensed and emulsified water droplets as templates. Such porous membranes may have great potential in fields such as separation, cell culture, and biosensing.

4.
Ecotoxicol Environ Saf ; 274: 116220, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38513531

RESUMO

Previous research investigating the correlation between prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and subsequent blood pressure (BP) in offspring has yielded limited and contradictory findings. This study was conducted to investigate the potential relationship between maternal PFAS levels during pregnancy and subsequent BP in early childhood. A total of 129 expectant mothers from the Shanghai Birth Cohort were included in the study. Using high-performance liquid chromatography/tandem mass spectrometry, we measured ten PFAS compounds in maternal plasma throughout the pregnancy. When the children reached the age of 4, we examined their systolic BP (SBP) and diastolic BP (DBP), along with mean arterial pressure (MAP) and pulse pressure (PP). Data interpretation employed multiple linear and logistic regression models, complemented by Bayesian kernel machine regression (BKMR).We found that the majority of PFAS concentrations remained stable during pregnancy. The linear and BKMR models indicated a positive relationship between the PFAS mixture in maternal plasma and offspring's DBP and MAP, with perfluorohexanesulphonic acid (PFHxS) having the most significant influence (PFHxS and DBP [first trimester:ß=3.03, 95%CI: (1.01,5.05); second trimester: ß=2.35, 95%CI: (0.94,3.75); third trimester: ß=2.57, 95%CI:(0.80,4.34)]; MAP [first trimester:ß=2.55, 95%CI: (0.64,4.45); second trimester: ß=2.28, 95%CI: (0.95,3.61); third trimester: ß=2.35, 95%CI:(0.68,4.01)]). Logistic regression highlighted an increased risk of prehypertension and hypertension in offspring with higher maternal PFHxS concentrations during all three trimesters [first trimester: OR=2.53, 95%CI:(1.11,5.79), second trimester: OR=2.05, 95%CI:(1.11,3.78), third trimester: OR=3.08, 95%CI:(1.40,6.79)]. A positive correlation was identified between the half-lives of PFAS and the odds ratio (OR) of prehypertension and hypertension in childhood (ß=0.139, P=0.010). In conclusion, this research found maternal plasma PFAS concentrations to be positively associated with BP in offspring, with PFHxS showing the most significant influence. This correlation remained consistent throughout pregnancy, and this effect was proportional to the half-lives of PFAS.


Assuntos
Ácidos Alcanossulfônicos , Poluentes Ambientais , Fluorocarbonos , Hipertensão , Pré-Hipertensão , Criança , Gravidez , Feminino , Humanos , Pré-Escolar , Pressão Sanguínea , Pré-Hipertensão/induzido quimicamente , Teorema de Bayes , Poluentes Ambientais/toxicidade , Fluorocarbonos/toxicidade , China , Hipertensão/induzido quimicamente , Ácidos Alcanossulfônicos/toxicidade
5.
Angew Chem Int Ed Engl ; 63(24): e202316299, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38422222

RESUMO

Vinylene-linked two-dimensional polymers (V-2DPs) and their layer-stacked covalent organic frameworks (V-2D COFs) featuring high in-plane π-conjugation and robust frameworks have emerged as promising candidates for energy-related applications. However, current synthetic approaches are restricted to producing V-2D COF powders that lack processability, impeding their integration into devices, particularly within membrane technologies reliant upon thin films. Herein, we report the novel on-water surface synthesis of vinylene-linked cationic 2DPs films (V-C2DP-1 and V-C2DP-2) via Knoevenagel polycondensation, which serve as the anion-selective electrode coating for highly-reversible and durable zinc-based dual-ion batteries (ZDIBs). Model reactions and theoretical modeling revealed the enhanced reactivity and reversibility of the Knoevenagel reaction on the water surface. On this basis, we demonstrated the on-water surface 2D polycondensation towards V-C2DPs films that show large lateral size, tunable thickness, and high chemical stability. Representatively, V-C2DP-1 presents as a fully crystalline and face-on oriented film with in-plane lattice parameters of a=b≈43.3 Å. Profiting from its well-defined cationic sites, oriented 1D channels, and stable frameworks, V-C2DP-1 film possesses superior bis(trifluoromethanesulfonyl)imide anion (TFSI-)-transport selectivity (transference, t_=0.85) for graphite cathode in high-voltage ZDIBs, thus triggering additional TFSI--intercalation stage and promoting its specific capacity (from ~83 to 124 mAh g-1) and cycling life (>1000 cycles, 95 % capacity retention).

6.
Soft Matter ; 19(26): 4916-4925, 2023 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-37340833

RESUMO

Fluorinated polymers are emerging as important alternatives for isoporous film fabrication by the breath figure technique, originating from the special characteristics endowed by fluorine elements such as low surface energy and good chemical stability. In this work, we design and synthesize polystyrenes (∼3600 Da) with perfluoroalkyl groups (-C3F7 or -C7F15) at both chain ends and hydrophilic oligo(ethylene glycol) units ((C2H4O)n, n = 1/2/3) in the chain middle by taking advantage of the bifunctional atom transfer radical polymerization (ATRP) initiators and post-substitution of the terminal bromine. We investigate the influence of the two disparate groups on the physical characteristics of the polymers and self-assembly behaviors during the dynamic breath figure process. It shows that the elongation of hydrophilic segments can greatly decrease the interfacial tension between the polymer solution and water (from 41.8 to 37.4 mN m-1), and the functionalization with perfluoroalkyl end groups diminishes the ability of the polymers to precipitate at the interface, as demonstrated by the cloud point results. Studies of the morphology of the porous films suggest that both low interfacial tension and strong capability of interfacial precipitation are beneficial to droplet stabilization and honeycomb pattern formation at low solution concentrations.

7.
Methods ; 207: 20-28, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36031139

RESUMO

Bladder cancer is a heterogeneous, complicated, and widespread illness with high rates of morbidity, death, and expense if not treated adequately. The accurate and exact stage of bladder cancer is fundamental for treatment choices and prognostic forecasts, as indicated by convincing evidence from randomized trials. The extraordinary capability of Deep Convolutional Neural Networks (DCNNs) to extract features is one of the primary advantages offered by these types of networks. DCNNs work well in numerous real clinical medical applications as it demands costly large-scale data annotation. However, a lack of background information hinders its effectiveness and interpretability. Clinicians identify the stage of a tumor by evaluating whether the tumor is muscle-invasive, as shown in images by the tumor's infiltration of the bladder wall. Incorporating this clinical knowledge in DCNN has the ability to enhance the performance of bladder cancer staging and bring the prediction into accordance with medical principles. Therefore, we introduce PENet, an innovative prior evidence deep neural network, for classifying MR images of bladder cancer staging in line with clinical knowledge. To do this, first, the degree to which the tumor has penetrated the bladder wall is measured to get prior distribution parameters of class probability called prior evidence. Second, we formulate the posterior distribution of class probability according to Bayesian Theorem. Last, we modify the loss function based on posterior distribution of class probability which parameters include both prior evidence and prediction evidence in the learning procedure. Our investigation reveals that the prediction error and the variance of PENet may be reduced by giving the network prior evidence that is consistent with the ground truth. Using MR image datasets, experiments show that PENet performs better than image-based DCNN algorithms for bladder cancer staging.


Assuntos
Neoplasias da Bexiga Urinária , Humanos , Neoplasias da Bexiga Urinária/diagnóstico por imagem , Teorema de Bayes , Redes Neurais de Computação , Algoritmos
8.
Environ Health ; 22(1): 72, 2023 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-37858165

RESUMO

BACKGROUND: Humans are widely exposed to perfluoroalkyl substances (PFAS), which have been found to be associated with various adverse birth outcomes. As blood pressure (BP) is an important parameter reflecting cardiovascular health in early life, it is necessary to investigate the association of PFAS exposure during early lifetime and BP in childhood. Therefore, we investigated the potential association between PFAS levels in umbilical cord blood and BP of the offspring at 4 years of age in a prospective cohort study. METHODS: PFAS in umbilical cord blood samples after birth were measured with high-performance liquid chromatography/tandem mass spectrometry in the Shanghai Birth Cohort. BP was measured at 4 years of age in the offspring. Multiple linear regression model was used to investigate the association between individual PFAS level and BP of the offspring. Bayesian kernel machine regression (BKMR) was used to analyze the relationship between the PFAS mixture and BP of the offspring, while weighted quantile sum (WQS) regression was utilized for sensitivity analysis. RESULTS: A total of 129 mother-child pairs were included in our analysis. In multiple linear regressions, we observed that long-chain PFAS, mainly including perfluorooctane sulfonate (PFOS), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUA), was negatively associated with systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP). BKMR showed that an increase in umbilical cord blood PFAS mixture levels was significantly associated with a decrease in SBP, DBP and MAP [Estimated differences (SD): -0.433 (0.161); -0.437 (0.176); -0.382 (0.179), respectively]. The most important component in the association with SBP, DBP, and MAP was PFUA. PFDoA was found to be positively associated with SBP, DBP and MAP in both models. Sensitivity analysis with WQS regression showed consistent results. CONCLUSION: Our findings suggested that umbilical blood PFAS exposure was negatively associated with BP in offspring at 4 years of age, including SBP, DBP, and MAP.


Assuntos
Ácidos Alcanossulfônicos , Poluentes Ambientais , Fluorocarbonos , Humanos , Pressão Sanguínea , Estudos Prospectivos , Sangue Fetal , Teorema de Bayes , China/epidemiologia
9.
Langmuir ; 38(40): 12207-12216, 2022 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-36184874

RESUMO

Immobilization of metal nanoparticles (NPs) on flexible substrates for surface-enhanced Raman scattering (SERS) has received great attention. Anchoring NPs on substrates generally involves the process of surface modification, thanks to its simple, universal, and nondestructive features. 2-Hydroxy-1,4-naphthoquinone (HNQ), a plant-derived compound used to dye hairs and nails, may interact with polyamine or metal ions to form a surface coating. Here, we report the formation of amino-quinone coatings via the co-deposition of HNQ and polyethyleneimine, which provides a functionalized platform to rapidly immobilize Ag NPs on substrates such as a poly(dimethylsiloxane) (PDMS) film to fabricate Ag-PDMS substrates for SERS detection. The detection concentrations are down to 10-8 M for rhodamine 6G. This work expands the system of surface co-deposition and further provides a facile route to prepare a highly efficient SERS substrate.


Assuntos
Nanopartículas Metálicas , Análise Espectral Raman , Nanopartículas Metálicas/química , Compostos Fitoquímicos , Poliaminas , Polietilenoimina , Prata/química
10.
Langmuir ; 38(31): 9587-9596, 2022 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-35881583

RESUMO

The advanced oxidation process of the photo-Fenton reaction can produce hydroxyl radicals with extremely strong oxidizing properties for the efficient and green degradation of various chemical and microbial pollutants. Herein, we report an approach to fabricating heterogeneous Fenton catalysts of ß-FeOOH nanorods on porous substrates triggered by mussel-inspired coatings of levodopa (3,4-dihydroxy-phenyl-l-alanine, l-DOPA) and polyethylenimine (PEI) for efficient photocatalytic dyes' degradation and sterilization. The l-DOPA-based coatings not only promote the formation and immobilization of ß-FeOOH nanorods on the porous substrates by strong coordination between catechol/carboxyl groups and Fe3+ but also improve the energy band structure of the Fenton catalysts through a valence band blue shift and band gap narrowing. The photo-Fenton catalysts prepared by the l-DOPA-based coatings exhibit high electron transport efficiency and improved utilization of sunlight. Only 2 h of mineralization is needed to fabricate these catalysts with excellent photocatalytic efficiency, in which the degradation efficiency of methylene blue can reach 99% within 30 min, whereas the sterilization efficiency of E. coli/S. aureus can reach 93%/94% within 20 min of the photo-Fenton reaction. Additionally, the prepared catalysts reveal a high photodegradation performance for various dyes including methylene blue, methyl blue, methyl orange, direct yellow, and rhodamine B. Furthermore, the catalysts retain high dye degradation efficiencies of above 90% after five photodegradation cycles, indicating cycling performance and good stability.


Assuntos
Corantes , Levodopa , Corantes/química , Escherichia coli , Peróxido de Hidrogênio/química , Ferro/química , Azul de Metileno , Porosidade , Staphylococcus aureus , Esterilização
11.
Langmuir ; 38(45): 13793-13802, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36327135

RESUMO

Thin-film-composite (TFC) nanofiltration membranes have found wide uses in environment remediation and industrial separation. There is a growing trend to avoid the use of organic solvents and toxic chemicals during membrane fabrication. Therefore, the aqueous fabrication of TFC membranes receives considerable interest as a green and sustainable process. However, it remains challenging to construct a defect-free and ultrathin film in a homogeneous aqueous phase without the assistance of an interface. The contra-diffusion process provides a special "interface" to confine the film formation within a narrow space by regulating the competition between precursor diffusion and interfacial reactions. Herein, Fe3+/tannic acid (TA) TFC membranes were fabricated by a contra-diffusion process. The effects of fabrication parameters on the Fe3+/TA TFC membrane microstructure and performance were also investigated. The negatively charged membrane performs a competitive Na2SO4 rejection of 95.6% with a permeation flux of 44.3 L m-2 h-1 under 0.6 MPa as well as more than 99.5% rejection to several anionic dyes. The as-prepared membranes perform superior nanofiltration performance compared to other reported Fe3+/TA-based membranes, owing to the thin and defect-free selective layers by self-regulation. Moreover, the membranes exhibit stable rejection during a long-term nanofiltration test.

12.
Entropy (Basel) ; 24(5)2022 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-35626496

RESUMO

Link prediction based on bipartite networks can not only mine hidden relationships between different types of nodes, but also reveal the inherent law of network evolution. Existing bipartite network link prediction is mainly based on the global structure that cannot analyze the role of the local structure in link prediction. To tackle this problem, this paper proposes a deep link-prediction (DLP) method by leveraging the local structure of bipartite networks. The method first extracts the local structure between target nodes and observes structural information between nodes from a local perspective. Then, representation learning of the local structure is performed on the basis of the graph neural network to extract latent features between target nodes. Lastly, a deep-link prediction model is trained on the basis of latent features between target nodes to achieve link prediction. Experimental results on five datasets showed that DLP achieved significant improvement over existing state-of-the-art link prediction methods. In addition, this paper analyzes the relationship between local structure and link prediction, confirming the effectiveness of a local structure in link prediction.

13.
Entropy (Basel) ; 24(7)2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35885189

RESUMO

Domain adaptation aims to learn a classifier for a target domain task by using related labeled data from the source domain. Because source domain data and target domain task may be mismatched, there is an uncertainty of source domain data with respect to the target domain task. Ignoring the uncertainty may lead to models with unreliable and suboptimal classification results for the target domain task. However, most previous works focus on reducing the gap in data distribution between the source and target domains. They do not consider the uncertainty of source domain data about the target domain task and cannot apply the uncertainty to learn an adaptive classifier. Aimed at this problem, we revisit the domain adaptation from source domain data uncertainty based on evidence theory and thereby devise an adaptive classifier with the uncertainty measure. Based on evidence theory, we first design an evidence net to estimate the uncertainty of source domain data about the target domain task. Second, we design a general loss function with the uncertainty measure for the adaptive classifier and extend the loss function to support vector machine. Finally, numerical experiments on simulation datasets and real-world applications are given to comprehensively demonstrate the effectiveness of the adaptive classifier with the uncertainty measure.

14.
Langmuir ; 37(12): 3721-3730, 2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-33734690

RESUMO

Mussel-inspired surface modification has received significant interest in recent years because of its simplicity and versatility. The deposition systems are still mainly limited to molecules with catechol chemical structures. In this paper, we report a novel deposition system based on a monophenol, vanillic acid (4-hydroxy-3-methoxybenzoic acid), to fabricate metal-phenolic network coatings on various substrates. The results of the water contact angle and zeta potential reveal that the modified polypropylene microfiltration membrane is underwater superhydrophobic and positively charged, showing applications in oil/water separation and dye removal. Furthermore, the single-face modified Janus membrane is promising in switchable oil/water separation. The results demonstrate a novel example of the metal-monophenolic deposition system, which expands the toolbox of surface coatings and facilitates the understanding of the deposition of phenols.

15.
Nano Lett ; 20(12): 8760-8767, 2020 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-33211495

RESUMO

Organic solvent nanofiltration (OSN) is regarded as a promising separation technology in chemical and pharmaceutical industries. However, it remains a great challenge in fabricating OSN membranes with high permeability and precise selectivity by simple, transfer-free, and up-scalable processes. Herein, we report lysozyme nanofilm composite membranes (LNCM) prepared by one-step methods with hydrophobic substrates at the air/water interface. The microporous substrates not only promote the heterogeneous nucleation of amyloid-like lysozyme oligomers to construct small pores in the formed nanofilms but also benefit for the simultaneous composition of LNCM via hydrophobic interactions. The constructed nanopores are reduced to around 1.0 nm, and they are demonstrated by grazing incidence small-angle X-ray scattering with a closely packed model. The LNCM can tolerate most organic polar solvents and the permeability surpasses most of state-of-the-art OSN membranes.


Assuntos
Filtração , Muramidase , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Solventes
16.
Angew Chem Int Ed Engl ; 60(26): 14636-14643, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34010463

RESUMO

Polymerization at the liquid-liquid interface has attracted much attention for synthesizing ultrathin polymer films for molecular sieving. However, it remains a major challenge to conduct this process outside the alkane-water interface since it not only suffers water-caused side reactions but also is limited to water-soluble monomers. Here, we report the interfacial polymerization at the alkane/ionic liquid interface (IP@AILI) where the ionic liquid acts as the universal solvent for diversified amines to synthesize task-specific polyamide nanofilms. We propose that IP@AILI occurs when acyl chloride diffuses from the alkane into the ionic liquid instead of being triggered by the diffusion of amines as in the conventional alkane-water system, which is demonstrated by thermodynamic partitioning and kinetic monitoring. The prepared polyamide nanofilms with precisely adjustable pore sizes display unprecedented permeability and selectivity in various separation processes.

17.
Angew Chem Int Ed Engl ; 60(5): 2346-2354, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33058424

RESUMO

Engineering coatings with precise physicochemical properties allows for control over the interface of a material and its interactions with the surrounding environment. However, assembling coatings with well-defined properties on different material classes remains a challenge. Herein, we report a co-assembly strategy to precisely control the structure and properties (e.g., thickness, adhesion, wettability, and zeta potential) of coatings on various materials (27 substrates examined) using quinone and polyamine building blocks. By increasing the length of the amine building blocks from small molecule diamines to branched amine polymers, we tune the properties of the films, including the thickness (from ca. 5 to ca. 50 nm), interfacial adhesion (0.05 to 5.54 nN), water contact angle (130 to 40°), and zeta potential (-42 to 28 mV). The films can be post-functionalized through the in situ formation of diverse nanostructures, including nanoparticles, nanorods, and nanocrystals. Our approach provides a platform for the rational design of engineered, substrate-independent coatings for various applications.

18.
Langmuir ; 36(6): 1454-1461, 2020 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-31983209

RESUMO

Porous materials have attracted great interest in recent years, and a variety of surface modification methods have been developed to endow porous materials with multifunctional applications. Herein, multifunctional porous materials are fabricated based on surface metallization. Metallized sponges with Ag and Cu are highly hydrophobic and are still hydrophobic under oil. The metallized sponges selectively adsorb oils from oil/water mixtures and can completely remove oils from water. We further demonstrate continuous oil-water separation by the metallized sponges with the aid of a peristaltic pump. The Ag-metallized materials show high catalytic performance for both chemical reduction and dye degradation. The catalytic reduction efficiency of 4-nitrophenol reaches 97.7% within 60 min and remains as high as 96% after 15 cycles. Moreover, the metallized materials show 99.99% bactericidal efficiency for both Staphylococcus aureus and Escherichia coli. Particularly, the Cu-metallized materials exhibit stable conductivity under deformation; and metal patterns are realized via the metallization method combined with a patterned mask, which may provide a feasible approach for flexible electronics. This work provides a versatile method to introduce metal coatings to porous materials, broadening the applications of porous materials.

19.
Langmuir ; 36(3): 742-753, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31895574

RESUMO

The linear shrinkage behavior in thermoresponsive diblock copolymer films and its potential application in temperature sensors are investigated. The copolymer is composed of two thermoresponsive blocks with different transition temperatures (TTs): di(ethylene glycol) methyl ether methacrylate (MEO2MA; TT1 = 25 °C) and poly(ethylene glycol) methyl ether methacrylate (OEGMA300; TT2 = 60 °C) with a molar ratio of 1:1. Aqueous solutions of PMEO2MA-b-POEGMA300 show a three-stage transition upon heating as seen with optical transmittance and small-angle X-ray scattering: dissolution (T < TT1), self-assembled micelles with core-shell structure (TT1 < T < TT2), and aggregation of collapsed micelles (T > TT2). Due to the restrictions in the polymer chain arrangement introduced by the solid Si substrate, spin-coated PMEO2MA-b-POEGMA300 films exhibit an entirely different internal structure and transition behavior. Neutron reflectivity shows the absence of an ordered structure normal to the Si substrate in as-prepared PMEO2MA-b-POEGMA300 films. After exposure to D2O vapor for 3 h and then increasing the temperature above its TT1 and TT2, the ordered structure is still not observed. Only a D2O enrichment layer is formed close to the hydrophilic Si substrate. Such PMEO2MA-b-POEGMA300 films show a linear shrinkage between TT1 and TT2 in a D2O vapor atmosphere. This special behavior can be attributed to the synergistic effect between the restrained collapse of the PMEO2MA blocks by the still swollen POEGMA300 blocks and the impedance of chain arrangement by the Si substrate. Based on this unique behavior, spin-coated PMEO2MA-b-POEGMA300 films are further prepared into a temperature sensor by implementing Ag electrodes. Its resistance decreases linearly with temperature between TT1 and TT2.

20.
Langmuir ; 36(22): 6228-6237, 2020 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-32388986

RESUMO

The impact of thermal history on the kinetic response of thin thermoresponsive diblock copolymer poly(diethylene glycol monomethyl ether methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate), abbreviated as PMEO2MA-b-POEGMA300, films is investigated by in situ neutron reflectivity. The PMEO2MA and POEGMA300 blocks are both thermoresponsive polymers with a lower critical solution temperature. Their transition temperatures (TTs) are around 25 °C (TT1, PMEO2MA) and 60 °C (TT2, POEGMA300). Thus, by applying different temperature protocols (20 to 60 or 20 to 40 to 60 °C), the PMEO2MA-b-POEGMA300 thin films experience different thermal histories: the first protocol directly switches from a swollen to a collapsed state, whereas the second one switches first from a swollen to a semicollapsed and finally to a collapsed state. Although the applied thermal histories differ, the response and final state of the collapsed films are very close to each other. After the thermal stimulus, both films present a complicated response composed of an initial shrinkage, followed by a rearrangement. Interestingly, a subsequent reswelling of the collapsed film is only observed in the case of having applied a thermal stimulus of 20 to 40 °C. The normalized film thickness and the D2O amount of each layer in the PMEO2MA-b-POEGMA300 films are consistent at the end of the two different thermal stimuli. Hence, it can be concluded that the thermal history does not influence the final state of the PMEO2MA-b-POEGMA300 films upon heating. Based on this property, these thin films are especially suitable for the temperature switches on the nanoscale, which may experience different thermal histories.

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