Microencapsulation of dodecyl acetate by complex coacervation of whey protein with acacia gum and its release behavior

Complex coacervation of whey protein(WP) with acacia gum(AG) was carried out in water with the presence of dodecyl acetate (DA),a component of insect sex pheromones,in order to obtain microcapsules with DA as the core material and WP-AG coacervate as the wall materials.Through variations in wall/core ratios,concentrations of the wall materials in capsule preparations,DA encapsulation was optimized,which showed a high DA encapsulation was achieved when coacervation was conducted at pH 3.5 with wall/core mass ratio at 3 combined with concentration of wall materials at 1.0 wt%.Morphology and the structure of DA loaded microcapsules were examined by scanning electron microscope,which showed the microcapsules were of core/shell structure with DA encapsulated in the inner of the microcapsules.DA release was examined and the behavior of the release was discussed.     

Synthesis,UV-curing Behavior and Surface Properties of New Fluorine-containing Aromatic Oxetane Monomers

In this paper,we combined high-end cationic UV-curable material with fluorinated chain obtaining a series of new fluorine-containing aromatic oxetane monomers via a mild nucleophilic substitution reaction.The structures and properties of monomers were characterized using 1H-NMR,19F-NMR,dynamic viscosity tests and differential scanning calorimetry (DSC).It was determined that all of the fluorinated monomers obtained had much lower viscosity and higher thermostability after the introduction of hexafluorobenzene.Then,UV-curable coatings were prepared using four fluorine-containing aromatic oxetane monomers (FOX1-4);the UV-curing kinetics,with three kinds of initiators,and properties of the cured films were evaluated using real-time Fourier transform infrared (FTIR) spectroscopy,water and diiodomethane contact angle tests,surface energy calculations and scanning electron microscopy (SEM).The FTIR spectroscopy results showed that the coatings possessed excellent conversion rate (＞ 99％ with liquid initiator PAG-201 in 150 s),and as the fluorine content increased,the monomers exhibited decreased mobility with the increasing viscosity and worse solubility with fluorinated monomers,resulting in a lower conversion rate.Moreover,the coatings possessed favorable hydrophobic and oleophobic properties and low surface energies owing to the fluoride chains floating to the membrane-air interface,which was also confirmed by discrete concave structures in SEM images.These new kinds of monomers can replace traditional fluorinated cationic monomers applied to the fingerprint resistant,fouling resistant,scratch resistant and anti-aging coatings,adhesives or printing ink materials.     

DSC study of cold and heat denaturation processes of β-lactoglobulin A with guanidine hydrochloride

The cold and heat denaturations of bovine β-lactoglobuhn A (β-lg A) has been studied in solutions of guanidine hydrochloride (GuHCl) by differential scanning calorimelry (DSC) The experimental results are presented and discussed.It is shown that the number of protons bound by the monomeric molecules of β-lg A was unchanged before and after its heat denaturation below pH 3,and that the activation energy of the heat denaturation was depressed owing to the presence of GuHCl.In the solutions with 2.50 and 3.06 mol/L of GuHCl,both the cold and heat denat-urations of β-lg A were observed.In comparison with the heat denaturation,the activation energy of cold denaturation was far lower and the number of GuHCl molecules bound by the unfolded polypeptide chains after cold denaturation increased a lot.The absolute value of the enthalpy of cold denaturation was larger than that of heat denaturation It was found by the analysis that the contribution to the total denaturational enthalpy of conformational change i     

NMR Analysis to Identify Biuret Groups in Common Polyureas

Polyureas(PU) are well known as a class of high impact engineering materials, and widely used also in emerging advanced applications. As a general observation, most of them are only soluble in a very limited number of highly protonic solvents, which makes their chemical structure analysis a great challenge. Besides the presence of abundant hydrogen bonding, the poor solubility of PU in common organic solvents is often ascribed to the formation of biuret crosslinking in their molecular chains. To clarify the presence of biuret groups in PU has been of great interest. To this end, two samples, based on hexamethylene diisocyanate(HDI) and toluene diisocyanate(TDI) respectively, were synthesized by precipitation polymerization of each of these diisocyanates in water-acetone at30 °C. Their chemical structures were analyzed by high resolution magic angle spinning(HR-MAS) NMR, and through comparison of their NMR spectra with those of specially prepared biuret-containing polyurea oligomers, it was concluded that biuret group was absent in all the PU prepared at 30 °C. In addition, this NMR analysis was also applied to a PU obtained by copolymerization of TDI with ethylene diamine(EDA) and water at 65 °C in EDA aqueous solution. It was confirmed that biuret unit was also absent in this PU and that EDA was more active than water towards TDI. The presence of EDA was crucial to the formation of uniform PU microspheres. This study provides therefore a reliable method for the analysis of PU chemical structure.     

Computational Simulation and Electrochemically Deposited Molecularly Imprinted Polymer-coated Carbon Glass Electrode for Triclosan Detection

Triclosan, a kind of multi-purpose biocide, was widely used household cleaning and personal care products. The widespread use of triclosan has potential risk to the ecotype and human health due to its release into sediment, surface and ground water resources. A molecularly imprinted electrochemical sensor for triclosan detection in cosmetic emulsion was synthesized and characterized. In order to determine the suitable monomer and evaluate the template-monomer geometry as well as the interaction energy in the template-monomer prepolymerization mixture, a computational study was applied. We found that the complex formed by hybrid monomers(triclosan(o-phenylenediamine-co-resorcinol)) had more hydrogen bonds and larger binding energy than that by single kind of monomers(triclosan(o-phenylenediamine)_2 and triclosan(resorcinol)_2). Therefore, hybrid monomers were used to synthesize the imprinted electrochemical sensor, which exhibits a high sensitivity and selectivity for triclosan sensing with the detection range 0～15 ng·mL~(-1) and detection limit 0.41 ng·mL~(-1).     

Preparation and Characterization of Microencapsulated Hexadecane Used for Thermal Energy Storage

Polyurea microcapsules about 2.5μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2,4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.     

MOF-derived Co_9S_8 nano-flower cluster array modified separator towards superior lithium sulfur battery

Lithium sulfur batteries with high energy density are thought to be the most potential energy storage technology that can be commercialized.However,the shuttle effect of polysulfides deteriorates its electrochemical performance.Herein,a novel Co_9 S_8 nanostructure derived from metal organic framework material(MOF) was explored by simple liquid phase reaction and heat vulcanization of2-methylimidazole and Co(NO_3)_2·6 H_2 O on the surface of the original PP separator.The Co_9 S_8 nano-flower cluster array wall was vertically and closely arranged with the thickness of 200 nm,and the polysulfide can be adsorbed by its physical and chemical action to slow down the "shuttle effect".It is found that the cell with the modified separator can achieve an ideal discharge capacity of about 600 mAh/g at 1 C.The specific capacity is maintained at 500 mAh/g after 200 cycles,with only 0.11% of capacity decay per cycle.It provides a new way for the utilization of MOF material derivatives to modify the separator in order to improve the electrochemical performance of lithium-sulfur batteries.     

Influence of Heat Treatment Time on Cathode Material Cr8O21 for Lithium Battery北大核心CSCD

Chromium oxide (Cr8O21) cathode material for lithium batteries was synthesized by thermal decomposition of chromium trioxide (CrO3) at high temperature. The electrochemical properties of chromium oxide depended on the time and temperature during the heat treatment. Pure phase chromium oxide was prepared, and the effects of heat treatment time on the structures and electrochemical properties of Cr8O21 were systematically studied. The first discharge mechanism of chromium oxide in lithium batteries was explored, and the results were similar to that in lithium-sulfur batteries. The crystal phases and electrochemical properties of the prepared chromium oxide were analyzed by TGA, XRD, SEM, EDS, ICP, EIS techniques and constant current discharge measurement. The results show that heat treatment time had an important impact. Extending the heat treatment time was beneficial to improve the electrochemical properties of the material. The less the amount of residual CrO3, the better the electrochemical performance. The severe oxidation reaction between CrO3 and the electrolyte caused the electrode to be corroded. The material obtained in 48 h exhibited excellent performance, complete crystallization, good morphology, and low electrochemical impedance. At a constant discharge current of 0.05 mA, the specific capacity of the material reached 383.26 mAh窑g-1 with the specific energy of 1153.83 mWh窑g-1 and the average discharge voltage of 3.01 V. This study provides an effective way to prepare pure phase chromium oxide and proves its potential application in the field of lithium batteries. © 2021 Authors. All rights reserved.     

Fabrication of C@Mo_xTi_(1-x)O_(2-δ) nanocrystalline with functionalized interface as efficient and robust PtRu catalyst support for methanol electrooxidation

A core shell structured C@Mo_xTi_(1-x)O_(2-δ)nanocrystal with a functionalized interface(C@MTNC-FI) was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO_2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process, infiltration of Mo dopants and carbon coating, which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell. Pt Ru nanoparticles(NPs) were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP). The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC) and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25% increase in durability. The improved catalytic performance is due to several aspects including ultrafine crystals of TiO_2 with abundant grain boundaries, Mofunctionalized interface with enhanced electron interactions, and core shell architecture with excellent electrical transport properties. This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.     

Perspective on the R&Ds in energy chemistry systems engineering

正1 Introduction Energy chemistry systems engineering(ECSE),the application of the principles of system engineering in the field of energy chemistry,is a rapidly developing cutting-edge interdiscipline.It is used for various processes and systems in the domain of energy chemistry,dealing with problems of the efficient conversion,comprehensive utilization and complementary integration of material and energy with the theories,methods and techniques of system engineering,in order to     

界面聚合法制备正二十烷微胶囊化相变储热材料

采用界面聚合的方法, 以甲苯鄄2,4-二异氰酸酯(TDI)和乙二胺(EDA)为反应单体, 非离子表面活性剂聚乙二醇壬基苯基醚(OP)为乳化剂, 合成了正二十烷为相变材料的聚脲包覆微胶囊. 结果表明, 二异氰酸酯和乙二胺按质量比1.9:1 进行反应. 以透射电镜和激光粒度分析仪分析微胶囊, 测得空心微胶囊直径约为0.2 μm, 含正二十烷微胶囊约为2-6 μm. 红外光谱分析证明, 壁材料聚脲是由TDI 及EDA 两种单体形成的. 正二十烷的包裹效率约为75%. 微胶囊的熔点接近囊芯二十烷的熔点, 而其储热量在壁材固定时随囊芯的量而变. 热重分析表明, 囊芯正二十烷、含正二十烷的微胶囊以及壁材料聚脲, 能够耐受的温度分别约为130 ℃、170 ℃及270 ℃.     

Microencapsulation of octadecane as a phase-change material by interfacial polymerization in an emulsion system

 Microcapsules containing phase-change material for thermal adaptable fiber application were synthesized and characterized. The microcapsules of about 1 μm in diameter were prepared using an interfacial polycondensation method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Octadecane was used as a phase-change material and NP-10 which is nonionic surfactant, was used as an emulsifier. To investigate the reaction ratio of monomers, microcapsules were synthesized with 3 g TDI and 0–4 g DETA. Polyurea microcapsules were formed not only by reaction with TDI and DETA, but also by reaction of TDI with hydrolyzed TDI at the interface. TDI was reacted with DETA in the weight ratio of 3:1. NP-10 was reacted with TDI to form urethane. The microcapsules containing octadecane showed a phase change of octadecane at 29–30 °C. The core content measured using the heat of fusion of octadecane was less than that calculated. The efficiency of octadecane encapsulation increased as the core content decreased. Received: 17 July 2001 Accepted: 13 September 2001     

正十六烷聚脲微胶囊化相变材料

用界面聚合法，合成了直径大约2.5 μm可用于热能储存含相变材料的聚脲包覆微胶囊.在含乳化剂的水溶液中，将溶有芯材正十六烷的有机相乳化成微米级油性液滴，随后加入的水溶性单体二胺与甲苯2,4-二异氰酸酯在胶束界面相互反应形成囊壁.分别用乙烯二胺，1,6-己二胺和它们的混合物作为水溶性单体进行了研究.并用红外光谱和热分析分别考察了不同胺类对微胶囊化学结构和热性质的影响.红外谱图显示合成了聚脲微胶囊，热重曲线表明含正十六烷的聚脲微胶囊能够耐受大约300 ℃高温，差示扫描量热测试表明所有样品均具有合适的相转变热，冷热循环实验揭示微胶囊能够维持储热容量不衰减.研究表明微胶囊化的正十六烷作为相变储热材料具有良好的应用前景.     

N,N,N′,N′,N″‐penta(methyl acrylate)diethylenetriamine: A novel ligand for atom transfer radical polymerization of methyl methacrylate

A novel ligand, N,N,N′,N′,N″‐penta (methyl acrylate) diethylenetriamine (MA₅‐DETA), was synthesized by the reaction of diethylenetriamine with methyl acrylate in almost quantitive yield. The polymerizations of methyl methacrylate with MA₅‐DETA as the ligand and α,α‐dichlorotoluene (DCT) and ethyl 2‐bromoisobutyrate (2‐EBiB) as the initiators, respectively, under different conditions were examined. The polymerization with CuCl/MA₅‐DETA/DCT was closely controlled in bulk and gave polymers with quite narrow molecular weight distributions (M_w/M_n's) of 1.16–1.29. The polymerization with the system CuBr/MA₅‐DETA/EBiB in bulk gave high activity. However, the system was not well controlled and gave the polymers with M_w/M_n = 1.35–1.53. The solution polymerization in anisole with CuBr/MA₅‐DETA/EBiB showed a better‐controlled nature. Moreover, the addition of CuBr₂ into the aforementioned system can further improve its controllability. The M_w/M_n's of the resulting polymers ranged from 1.11 to 1.21. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1963–1969, 2004     

A Study of the Slow Release of Urea from Microcapsules with TDI as the Wall-Sealing Treatment

The release of urea from ethylcellulose coated microcapsules was efficiently reduced by post-treatment with toluene-2,4-diisocyanate (TDI) in n-hexane. Our results show that TDI can be used as a sealant which modifies the shell characteristics of the ethylcellulose film. The modification is rather complicated in that it probably includes cross-linking between ethylcellulose and TDI, a reaction between urea and TDI, and biuret or polyurea formation from TDI absorbed on the microcapsules surface with moisture. The influence of post-treated conditions on the release of urea from ethylcellulose shell was studied.     

Polyurea nanocapsules obtained from nano‐emulsions prepared by the phase inversion temperature method

We describe here a new and simple method for preparation of polyurea nanocapsules from nanodroplets that were obtained by the phase inversion temperature (PIT) method. In the first stage, a nano‐emulsion was prepared, by a heating–cooling cycle, in which the oil phase contained an oil soluble monomer (toluene 2 , 4 ‐diisocyanate (TDI)). In the second stage, a water‐soluble monomer and crosslinker (diethylenetriamine (DETA)) was added, leading to formation of a polymeric shell by an interfacial polycondensation reaction. The new method was demonstrated for obtaining nanocapsules of about 100 nm, in which hexadecane, dodecane, or decane were the core materials, without using any special equipment. The morphology and structure of the nanocapsules were evaluated by attenuated total reflection Fourier transform infrared (ATR‐FTIR) measurements and electron microscopy. The thermal behavior of the nanocapsules containing hexadecane was studied by Differential Scanning Calorimetry (DSC) measurements, indicating that such nanocapsules can be utilized in thermal energy storage. Copyright © 2010 John Wiley & Sons, Ltd.     

A new cross‐linked system of silicone rubber based on silicone‐polyurea block copolymer

A new cross‐linked system of silicone rubber (SR) was obtained from silicone‐polyurea block copolymers that was synthesized with aminopropyl terminated polydimethylsiloxane and (4‐isocyanatocyclohexyl)‐methane. SR possessed self‐reinforced and physical cross‐linked structure. It had better mechanical properties that the hardness, the tensile strength, and the elongation at break could reach 65 Shore A, 3.78 MPa, and 458% with the polyurea segment content ranging from 2.01% to 9.13% by weight . The hydrogen bond that led to the physical cross‐linked structure was proved byFourier transform infrared spectroscopy. The microphase separated structure that caused the self‐reinforcement was illustrated by scanning electron microscopy, X‐ray diffraction analysis, and dynamic mechanical analysis. Fourier transform infrared spectroscopy results showed the hydrogen bond formation between the polyurea units. Scanning electron microscopy, dynamic mechanical analysis, and X‐ray diffraction analysis results proved the microphase separation existed between polyurea units and ―Si―O―Si― chains. The increase of polyurea contents enhanced the binding of hydrogen bond and improved the extent of microphase separation. Accordingly, it decreased the thermal properties and lowered the glass transition temperature (T_g) from −108°C to −114°C. Also, the increase of polyurea contents increased the hydrophobicity of SR that the surface free energy could reach to −24.81 mN/m.     

Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

A polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The T_g of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388     

Efficient synthesis of β‐(1,6)‐linked oligosaccharides through microwave‐assisted glycosylation

A microwave‐assisted glycosylation method was developed for efficient synthesis of oligosaccharides. Di‐functional AB monomers, 2,3,4‐tri‐O‐acetyl‐α‐d ‐galactopyranosyl bromide ( 3a ) and 2,3,4‐tri‐O‐acetyl‐α‐d ‐glucopyranosyl bromide ( 3b ) were designed and synthesized as weakly reactive monomers to avoid unwanted glycosylation or degradation during preparation and storage. The glycosylations of these monomers gave low conversions and low molecular weight oligosaccharides at rt, reflux, and under low microwave energy irradiation. However, the glycosylation became very effective when high microwave energy was applied, giving 100% conversion and producing oligosaccharides with M_n = 4.76 kDa for 3a and M_n = 4.05 kDa for 3b. The acetylated oligosaccharides were further subjected to deprotection for structural analysis, which indicated the oligosaccharides contain predominantly linear β‐(1,6)‐glycosyl linkages. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3693–3699     

One‐component,double‐chromophoric thioxanthone photoinitiators for free radical polymerization

Two one‐component, double‐chromophoric thioxanthone photoinitiators, namely TX‐EDA and TX‐DETA were synthesized by the reaction of thioxanthone aldehyde (TX‐A) with ethylenediamine (EDA) and diethylenetriamine (DETA), respectively via a facile Schiff base reaction. Both photoinitiators were characterized by spectral analysis and photobleaching studies. DFT calculations are employed to reveal the contribution of the different orbitals to the excitation of the initiators. The double‐chromophoric nature of the initiators gives rise to an increased absorption in the near UV region when compared with the pristine TX‐A. Photoinitiated polymerization of various vinyl monomers with TX‐EDA and TX‐DETA has been investigated in the presence and absence of a co‐initiator and compared for formulations consisting of precursor TX‐A. In addition, real‐time FTIR spectroscopic studies were performed in methyl methacrylate polymerization with both initiators. The higher efficiency observed with TX‐DETA may be attributed to the additional hydrogen donating sites adjacent to nitrogen atoms. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3475–3482