Materials In Aqueous Solution Research Articles

Constituting of a new surface‐initiating system on polymeric microspheres and preparation of basic protein surface‐imprinted material in aqueous solution

In this work, a new surface‐initiating system was constituted on the surfaces of cross‐linked polyvinyl alcohol (CPVA) microspheres, and on this basis, papain surface‐imprinted material was successfully prepared in aqueous solution. CPVA microspheres were modified with chlorethamin as reagent, and so a mass of primary amino group was introduced onto CPVA microspheres. Whereupon, a surface initiating system (−NH2/S2O82−) was formed at the interface between the microspheres and aqueous solution, in which papain as template protein, 4‐styrene sulfonate (SSS) as functional monomer, N,N′‐methylenebisacrylamide (MBA) as cross‐linker and (NH4)2S2O8 as initiator were all dissolved. In neutral solution, the polypeptide chains of papain as a basic protein were positively charged, and the molecules of anionic monomer SSS would spontaneously gather around papain polypeptide chain, forming complex by right of strong electrostatic interaction. The free radicals produced on CPVA microspheres initiated the monomer SSS around papain polypeptide chain and the cross‐linker MBA to produce graft/cross‐linking polymerization, and at the same time, papain macromolecules were embed in the cross‐linked networks. As a result, the graft/cross‐linking polymerizing of SSS and the molecule imprinting of papain were synchronously carried out, and papain surface‐imprinted material, MIP‐PSSS/CPVA microspheres, was obtained. The experimental results show that the papain surface‐imprinted material has excellent binding affinity and high recognition selectivity for papain. The binding capacity of MIP‐PSSS/CPVA microspheres for papain reaches 44 mg/g, and relative to another basic protein, trypsin (TRY) as contrast protein, the selectivity coefficient of MIP‐PSSS/CPVA microspheres for papain is 14.35, displaying very high recognition specificity.

Defective molybdenum sulfide quantum dots as highly active hydrogen evolution electrocatalysts

Molybdenum disulfide (MoS2), a promising non-precious electrocatalyst for the hydrogen evolution reaction with two-dimensional layered structure, has received increasing attention in recent years. Its electrocatalytic performance has been limited by the low active site content and poor conductivity. Herein, we report a facile and general ultrafast laser ablation method to synthesize MoS2 quantum dots (MS-QDs) for electrocatalytic HER with fully exposed active sites and highly enhanced conductivity. The MS-QDs were prepared by ultrafast laser ablation of the corresponding bulk material in aqueous solution, during which they were partially oxidized and formed defective structures. The as-prepared MS-QDs demonstrated high activity and stability in the electrocatalytic HER, owing to their very large surface area, defective structure, abundance of active sites, and high conductivity. The present MS-QDs can also find application in optics, sensing, energy storage, and conversion technologies.

Metal Complexes Based on 2‐[5‐(3,5‐Dibromophenyl)‐2H‐1,2,4‐triazol‐3‐yl]pyridine and Their Composites with CH3NH3PbI3: Structures, Band Gaps, and Enhanced Optoelectronic Properties

From 2‐[5‐(3,5‐dibromophenyl)‐2H‐1,2,4‐triazol‐3‐yl]pyridine (HL), three metal(II) complexes formulated as NiL2(HL)·DMF (1; DMF = N,N‐dimethylformamide), NiL2 (2), and CuL2 (3) were synthesized solvothermally and characterized by single‐crystal X‐ray diffraction. Among them, 2 and 3 are isostructural, except for the different metal(II) centers in their structures. The three metal(II) complexes all exhibit mononuclear structures but possess different band structures. Density functional theory (DFT) calculations revealed that 2 and 3 are semiconductors, and their perovskite CH3NH3PbI3 (P) composite materials, 2@P and 3@P, were synthesized. The largest photocurrent densities obtained for the two composite materials are much higher than those obtained for the corresponding complexes under intermittent visible‐light illumination (λ > 420 nm), as the suitable band gaps and matched energy levels of the complexes and P prevent the recombination of photoinduced electron–hole pairs. In addition, the stable photocurrent responses of the two composite materials in aqueous solution are associated with coverage of the surface of P by the insoluble complex, which improves the water resistance of P.

A Proof of Concept Study on Utilising a Non-invasive Microwave Analysis Technique to Characterise Silver Based Materials in Aqueous Solution

This paper reports on the feasibility of using a novel and robust microwave sensing technique to analyse and detect silver materials in an aqueous solution. Two products are tested, namely: silver chloride and silver oxide. The study mainly focused on indicating the difference between them and also any change in the size/size distribution of the sample. A microwave sensor designed previously is utilised to identify the potential of the technique to carry out the analysis. The results are presented as microwave spectrums that are the material response to microwaves. The results have shown that the technique has reasonably indicated the change in material type as well as size distribution. The results also show that these curves are distinguishable and can be related to the material and the change in its size. It is concluded that there is a potential of extending this technique to determine various other properties of silver products. The study suggests a design and development of a bespoke unit as a dedicated analysis tool and to address any anomalies arising from the current feasibility. This will have a huge industrial benefit in terms of cost reduction and time associated with the industrial analysis of silver material.

Physicochemical characterization of in situ drug-polymer nanocomplex formed between zwitterionic drug and ionomeric material in aqueous solution

Biocompatible polymeric materials with the potential to form functional structures, in association with different therapeutic molecules, in physiological media, represent a great potential for biological and pharmaceutical applications. Therefore, here the formation of a nano-complex between a synthetic cationic polymer and model drug (ampicillin trihydrate) was studied. The formed complex was characterized by size and zeta potential measurements, using dynamic light scattering and capillary electrophoresis. Moreover, the chemical and thermodynamically stability of these complexes were studied. The ionomeric material, here referred as EuCl, was obtained by equimolar reaction between Eudragit E and HCl. The structural characterization was carried out by potentiometric titration, FTIR spectroscopy, and DSC. The effect of pH, time, polymer concentration and ampicillin/polymer molar ratio over the hydrodynamic diameter and zeta potential were established. The results show that EuCl ionomer in aqueous media presents two different populations of nanoparticles; one of this tends to form flocculated aggregates in high pH and concentrations, by acquiring different conformations in solution by changing from a compact to an extended conformation. Moreover, the formation of an in situ interfacial polymer-drug complex was demonstrated, this could slightly reduce the hydrolytic degradation of the drug while affecting its solubility, mainly under acidic conditions.

Electrochemical Behaviors of Directly Deposited Pt on Specific CNT As an Electrocatalyst for ORR

Pt has been considered the best element for ORR in acidic condition in the point of activity, stability and power density. Pt catalysts for ORR have been often prepared using Pt compounds as starting material in aqueous solutions. The melting temperature, Tamman temperature and Huettig temperature of Pt are much higher than those of Pt compounds such as chlorides and oxides unlike Ni, Cu (1). It might be effective to deposit Pt metal directly on support to get better dispersed catalyst particles compared with the conventional methods. A liquid phase process and gas phase processes were found to be able to afford higher activity than conventional methods for various supporting materials. It was found that specific CV curves and extremely high mass activity in the case of CNT with low D/G as a catalyst support. as shown in Fig.1. The measurement condition was executed under the condition deciced based on the discussion with Y. Takasu and W. Sugimoto (2). It is very interesting that high ORR mass activity and the strong shift of HUPD to lower potential can be observed at the same time(3,4) in the electronic structure of Pt surface. We have started to discuss this behavior related with the surfacee electronic structure of Pt, the bonding between Pt and C, stability of the catalyst.

Synthesis and characterization of novel epoxy resins-filled microcapsules with organic/inorganic hybrid shell for the self-healing of high performance resins

Novel microcapsules (MCs) with organic/inorganic hybrid shell were successfully fabricated using epoxy resin as core material and nano boron nitride (BN) and mesoporous silica (SBA-15) as inorganic shell materials in aqueous solution containing a water-compatible epoxy resin curing agent. The morphologies, thermal properties and Young's moduli of MCs were investigated. The results indicated that epoxy resins were encapsulated by BN/SBA-15/epoxy polymer hybrid layer, the resulting MCs were spherical in shape and the introduction of inorganic particles made MCs had rough surface morphology. The mean modulus value of MCs was from 2.8 to 3.1 GPa. The initial decomposition temperature (Tdi) of MCs at 5 wt% weight loss was from 309 to 312°C. MCs showed excellent thermal stability below 260°C. The structures and properties of MCs could be tailored by controlling the weight ratio of inorganic particle. When the weight ratio of BN to SBA-15 was 0.15:0.10, MCs had the highest Tdi and modulus. The resulting MCs were applied to high performance 4,4′-bismaleimidodiphenylmethane/O,O′-diallylbisphenol A (BMI/DBA) system to design high performance BMI/DBA/MC systems. Appropriate content of MCs could improve the fracture toughness and maintain the glass transition temperature (Tg) of BMI/DBA system. The core materials released from fractured MCs could bond the fracture surfaces of the BMI/DBA matrix through the polymerization of epoxy resins. When the healing temperature schedule of 100°C/2h+150°C/1h was applied, 15 wt% MCs recovered 98% of the virgin fracture toughness of BMI/DBA. Copyright © 2016 John Wiley & Sons, Ltd.

Electrochemical and microgravimetric studies of poly[3,4-ethylenedioxythiophene]-tyrosinase biocomposite material electrodeposited onto gold electrodes by a sinusoidal voltages method

The electrodeposition of poly(3,4-ethylenedioxythiophene)-tyrosinase (PEDOT-Ty) biocomposite material onto gold electrode has been achieved by means of a sinusoidal voltages (SV) method. The SV method consists in the superimposition of a sinusoidal voltage (sin wave) with fixed frequency and amplitude onto a d.c. potential. The influence of electrochemical parameters like frequency and amplitude of SV signal, d.c. potential value, deposition time, on the electrodeposition process has been investigated. The biocomposite material has been prepared as a thin layer onto quartz crystals coated with gold. The frequency change of the quartz crystal during the electrodeposition of the biocomposite material was recorded simultaneously with the measured current response. The morphology of the deposited PEDOT-Ty coatings was investigated by scanning electron microscopy. The electrochemical behavior of the biocomposite material in aqueous solution was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The use of d.c. potential value of 0.6 V revealed the contribution of the SV component to the electrodeposition process. The PEDOT-Ty modified electrode was used as an electrochemical biosensor in the voltammetric determination of dopamine in the presence of hydroquinone. The analytical performances of the prepared biosensors were also investigated.

Stability analysis of functionalized mesoporous carbon materials in aqueous solution

Mesoporous carbons obtained by soft and hard template methods were oxidized by ammonium persulfate under different conditions. The functional groups present on the surface of carbon materials were identified by FT-IR and thermogravimetric studies. Longer time of oxidation process was favorable for generation of higher density of carboxylic, phenolic and etheric groups. The stability of pristine and functionalized mesoporous carbons dispersed in water was analyzed by multiple light scattering and laser diffraction methods. Additionally, the zeta potential of mesoporous carbons suspensions was measured. Particle–particle interactions, particle size and their density determined the sedimentation behavior of materials in aqueous solution. Non-modified CKIT-6 and CSBA-15 exhibited higher transmission level than the oxidized materials. Higher transmission intensity is related to more intense sedimentation. The results indicate that the dispersion of functionalized CKIT-6 and CSBA-15 in a liquid phase is much more stable than that of non-modified mesoporous carbon materials. In contrast, for the carbon samples obtained by the soft template method, the modification did not produce significant changes in the intensity of back-scattered light.

Surface Basicity Induced RuO2 Modification on Nanosized Li-Rich Cathode Li1.26Fe0.22Mn0.52O2 with Superior Electrochemical Performance

In this study, nanosized Li1.26Fe0.22Mn0.52O2 are modified with conductive RuO2 by using the surface basicity of Li-rich materials in aqueous solution to induce a chemically deposit of Ru3+. No additional precipitant is added. After heat-treatment, RuO2 modifies the surface of nano-particles verified by Energy Dispersive Spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The deposition process accompanies chemical-delithium activation of Li2MnO3 component. As a result, the intensity of superlattice peaks distinctly reduces monotonously in XRD patterns. And the electrode performances about the initial coulombic efficiency, the capacity and rate capability are improved greatly. In addition, for RuO2 modified samples, a new discharge plateau around 2.8 V appears, which is ascribed to spinel-like structure, enhancing the electrochemical activity of electrode. This facile modification method adopted in the work can be feasible and beneficial toward advanced Li-rich cathode materials.

Synthesis, Crystal Structure, Spectroscopic Properties, and Interaction with Ct-DNA of Zn(II) with 2-Aminoethanethiol Hydrochloride Ligand.

The zinc(II) complex (C2H6NS)2Zn·ZnCl2 was synthesized with 2-aminoethanethiol hydrochloride and zinc sulfate heptahydrate as the raw materials in aqueous solution. The composition and structure of the complex were characterized by elemental analysis, infrared spectra, single crystal X-ray diffraction, and thermogravimetry. The crystal structure of the zinc(II) complex belongs to monoclinic system, space group P 21/n, with cell parameters of a = 0.84294(4), b = 0.83920(4), c = 1.65787(8) nm, Z = 2, and D = 2.041 g/cm3. In this paper, the interaction of complex with Ct-DNA was investigated by UV-visible and viscosimetric techniques. Upon addition of the complex, important changes were observed in the characteristic UV-Vis bands (hyperchromism) of calf thymus DNA and some changes in specific viscosity. The experimental results showed that the complex is bound to DNA intercalative (intercalation binding).

Specific ionic effect for simple and rapid colorimetric sensing assays of amino acids using gold nanoparticles modified with task-specific ionic liquid

In this study, a novel task-specific ionic liquid functionalized gold nanoparticle (TSIL-GNP) was successfully prepared and applied in the recognition of amino acids. Particularly, the surface of GNP was modified with the ionic liquid containing carbamido and ester group via thiol, which was characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The stability of this material in aqueous solution improves apparently and can remain unchanged for more than three months. The effect of pH was also discussed in this study. Attractive ionic interaction would effectively weaken intensity of the covalent coupling between the metal ion and the functional groups of amino acids. Thus, TSIL-GNP was successfully applied to recognizing serine, aspartic acid, lysine, arginine, and histidine in the presence of Cu2+ through distinctive color changes. Suspension would be generated once a spot of cysteine was added into the GNPs solution. Results indicated that it had a good linear relationship between extinction coefficients and concentration of amino acids in a wide range of 10−3–10−6 M. Moreover, the proposed strategy was successfully used to analyze the histidine in urinary samples. In brief, TSIL-GNP is a suitable substrate for discrimination of five amino acids in a rapid and simple way without sophisticated instruments.

Chitosan membranes for tissue engineering: comparison of different crosslinkers

Chitosan (CS), a derivative of the naturally occurring biopolymer chitin, is an attractive material for biomedical applications thanks to its biocompatibility, biodegradability, antibacterial properties and ability to enhance cell adhesion and growth compared to other biopolymers. However, the physical and mechanical stability of CS based materials in aqueous solutions is limited and crosslinking agents are required to increase CS performances in a biological environment. In this work, the effect of three highly-biocompatible crosslinkers as genipin (GP), γ-glycidoxypropyltrimethoxysilane (GPTMS), dibasic sodium phosphate (DSP) and a combination of GPTMS and DSP (GPTMS_DSP) on CS physicochemical, thermal, morphological, mechanical properties, swelling and degradation behavior was investigated. Infrared spectroscopy and thermogravimetric analyses confirmed the chemical reaction between CS and the different crosslinkers. CS wettability was enhanced when CS was DSP ionically crosslinked showing contact angle values of about 65° and exhibiting a higher swelling behavior compared to covalently crosslinked films. Moreover, all the crosslinking methods analyzed improved the stability of CS in aqueous media, showed model molecule permeation in time and increased the mechanical properties when compared with non-crosslinked films.The possibility to tailor the final properties of CS scaffolds through crosslinking is a key strategy in applying CS in different biomedical and tissue engineering applications. The obtained results reveal that the optimization of the crosslinking mechanism provides CS membrane properties required in different biomedical applications.

Enhanced Dispersion of TiO2 Nanoparticles in a TiO2/PEDOT:PSS Hybrid Nanocomposite via Plasma-Liquid Interactions.

A facile method to synthesize a TiO2/PEDOT:PSS hybrid nanocomposite material in aqueous solution through direct current (DC) plasma processing at atmospheric pressure and room temperature has been demonstrated. The dispersion of the TiO2 nanoparticles is enhanced and TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased electrical conductivity was observed for the plasma treated TiO2/PEDOT:PSS nanocomposite. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma treated TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are proposed to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer binding.

Photocatalytic valorization of ethanol and glycerol over TiO2 polymorphs for sustainable hydrogen production

Photocatalytic reforming of renewable raw materials in aqueous solutions represents a valid possibility for the valorization of wastes from agricultural and industrial processes. In this study, we prepared TiO2 materials with different phase compositions by changing the urea/Ti molar ratio employed during the hydrothermal preparation method. After deposition of Pt nanoparticles, the photocatalytic H2 production was investigated using ethanol and glycerol as sustainable sacrificial agent. While anatase/rutile nanocomposites showed poor catalytic activity, the anatase/brookite nanocomposites showed more promising performances. Specifically, the anatase-rich materials showed the best performances on mass bases. When normalized with respect to the surface area of the photocatalysts, the activity continuously increased with the brookite content, indicating that exposed facets of brookite possess an intrinsic higher activity than that of the other polymorphs.

Facile synthesis of allyl resinate monomer in an aqueous solution under microwave irradiation

We have developed a facile method for production of allyl resinate monomer (allyl rosin ester) via a phase transfer reaction under microwave irradiation. The synthesis of allyl resinate was conducted using allyl chloride and sodium resinate as starting materials in aqueous solution at 50° for 30 min with a yield of 94.7%, which is 20% higher than conventional heating method. The products precipitated spontaneously from the aqueous phase after reaction, which significantly facilitated the subsequent separation of monomer products. The synthesized monomer product appeared as a viscous liquid, with a viscosity of 460 mPa ⋅s at 25° and a density of 1.0469 g/cm3. The physical and chemical properties suggested that the synthesized monomer has great potential for free radical polymerization. A facile method for production of allyl resinate monomer via a phase transfer reaction was developed. Microwave irradiation could significantly improve the formation of allyl resinate monomer. The replacement of solvents with water has potential to reduce the production cost of the monomers.

Capacity Fade Mechanisms of NaTi2(PO4)3 When Used As an Aqueous Anode

The capacity fade of NaTi2(PO4)3 when used as an anode material in aqueous electrolytes was investigated using electrochemical methods including electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT), as well as transmission electron microscopy (TEM) and x-ray diffraction (XRD). Both EIS and GITT indicated a continual increase in resistance of the synthesized material with little change in the diffusion rate of the sodium ion into the structure. XRD showed no change in crystallinity of the material after cycling. Morphological characterization using TEM showed an amorphous sodium phosphate layer formed between the in-situ carbon coating and the NaTi2(PO4)3 particles during synthesis when titania particles >100nm were used in the precursor powder. This layer was not present when smaller titania particles were used. Additionally, TEM showed the in-situ carbon coating became detached from the active material upon cycling. We believe this detachment of the conductive coating is the primary cause of capacity fade during cycling when the small titania particles are used in the synthesis. A better understanding of the detachment mechanism is needed to improve the cycle stability of NaTi2(PO4)3 materials in aqueous solutions.

Highly sensitive and selective fluorescent detection of rare earth metal Sn(II) ion by organic fluorine Schiff base functionalized periodic mesoporous material in aqueous solution

Abstract A Schiff base 3-((4-aminophenyl)imino)-5-fluoroindolin-2-one (APIFI) functionalized mesoporous material (APIFI-SBA) has been first developed by covalent binding with epoxypropoxyl groups on the inner surface of siliceous wall. The obtained material has been characterized by small angle X-ray diffraction, nitrogen adsorption–desorption and Fourier transform infrared spectroscopy. The results indicate that the Schiff base molecule APIFI is successfully immobilized within the channels of mesoporous material with linked ligand. Moreover, the ordered porous structure of mesoporous host is still retained on the Schiff base functionalized mesoprous material. The material APIFI-SBA shows high sensitivity and selectivity of detecting Sn2+ ions in aqueous media. A good linearity between the fluorescence intensity of the material and the concentration of Sn2+ ion is constructed, which enables it as a fluorescent chemosensor for detecting Sn2+ ion in aqueous solution. In future, it is potential to be used as a novel chemosensor for a lot of practical applications in chemical, environmental and biological systems.

Adsorption Characteristics of Bisphenol A onto Low-Cost Modified Phyto-Waste Material in Aqueous Solution

The potential of agricultural waste materials for the removal bisphenol A (BPA) from aqueous solu- tion was investigated. BPA is an endocrine-disrupting compound(EDC) used mainlyintheplasticmanufactur- ingindustry. It maybe hazardousto humansand animals because of its estrogenic activity. Agricultural wastes are sustainable adsorbents because of their low cost and availability. Hence, this study investigated the removal of BPA from water by adsorption onto treated coir pith, coconut shell and durian peel. The adsorption of BPA from water onto adsorbent was evaluated using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). The effects of mor- phology, functional groups, and surface area on adsorp- tion before and after pretreatment with sulfuric acid and reaction were investigated, and it was found that the treated adsorbent were able to remove BPA. Carbonyl andhydroxylgroupshadappearinlargenumberinFTIR analysis. The present study indicates that coir pith had removed 72 % of BPA with adsorption capacity of 4.308 mg/g for 24 h, followed by durian peel (70 %, 4.178 mg/g) and coconut shell (69 %, 4.159 mg/g). The results proved that these modified phyto-waste were promising materials as alternative adsorbent for the re- moval of BPA from aqueous solution.

Aqueous Lithium-Ion Batteries Using O2 Self-Elimination Polyimides Electrodes

Lithiated negative electrode materials (in discharge state) in aqueous solutions could be oxidized in the presence O2 and H2O, resulting in their poor charge/discharge cycle life. In the present work, we reported that lithiated polyimide can be oxidized by O2 in aqueous solution without much negative effect on its charge/discharge cyclability. The lithiated polyimide is converted to the almost identical polyimide structure by O2 oxidation in the aqueous solution based on FTIR spectra (O2 self-elimination performance). We also confirmed the good charge/discharge voltage profile and capacity of polyimide as an anode material in aqueous solutions. A sealed polymide-AC/LiNO3/LiMn2O4 aqueous LIB exhibited excellent cycle life with a capacity retention above 95% after 1000 charge/discharge cycles on 2C rate (charge/discharge) at room temperature, even when the battery was overcharged once after the 50th cycle.