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1.
羟乙基淀粉的羟乙基取代位置的研究   总被引:4,自引:0,他引:4  
将羟乙基淀粉进行甲基化-水解-还原乙酰化反应,产生羟乙基葡萄糖的部分甲基化糖醇乙酸酯衍生物,应用气相色谱/化学电离质谱(GC/CIMS)和气相色谱/电子轰击质谱/质谱(GC/EIMS/MS)联用技术研究了羟乙基在淀粉糖环上的取代位置,发现G-2位取代的量是总取代量的82.0%。  相似文献   

2.
Journal of Thermal Analysis and Calorimetry - The study is focused on the influence of a water-soluble polymer (in weight fraction up to 1.5%), cellulose derivatives—hydroxyethyl methyl...  相似文献   

3.
Hydroxyethyl cellulose sulfate (HECS) was synthesized by sulfation of hydroxyethyl cellulose with N(SO3Na)3, which was manufactured by reaction of sodium bisulfite and sodium nitrite. Barium sulfate nephelometry and light scattering method were used to determine degrees of substitution (DSs) and molecular weights (Mws), respectively. Sulfate products with DS values from 0.26 to 1.88 and Mw in the range of 12.1–54.8 kDa were obtained at temperatures from 30°C to 80°C. Furthermore, the anticoagulant activity of HECS with different DSs, concentrations, and Mws was studied. Clotting assays revealed that the introduction of sulfate groups into hydroxyethyl cellulose could improve its anticoagulant activity.  相似文献   

4.
Two previously unknown phenomena were observed in studying the reduction of selenious acid with ascorbic acid in an aqueous hydroxyethyl cellulose solution: (1) formation of nanoparticles of amorphous Se0 with uniform particle size distribution and mean particle radius of 15 ± 4 nm and (2) adsorption of more than 3000 macromolecules on these nanoparticles with formation of spherical nanostructures.  相似文献   

5.
Environmentally friendly biocomposites were prepared by blending wheat gluten(WG)as a matrix, hydroxyethyl cellulose(HEC)as a filler,and glycerol as a plasticizer,followed by thermo-molding of the mixture at 120°C for crosslinking the matrix.Moisture absorption,tensile properties,dynamic mechanical analysis,and dynamic rheology were evaluated in relation to the glycerol content.Tensile strength and modulus drop dramatically with increasing glycerol content,which is accompanied by significant depression in the glass transition temperature and improvement in the extensibility of the biocomposites.  相似文献   

6.
李伟  路福绥  翟利利  王祜英  郭雯婷 《应用化学》2011,28(10):1108-1113
采用原位聚合法以三聚氰胺-甲醛树脂为壁材制备了甲维盐微胶囊。 探讨了不同黏均相对分子质量羟乙基纤维素作为乳化剂对微胶囊表面形貌、粒径及其分布、包覆率与载药量的影响,对使用不同黏均相对分子质量羟乙基纤维素作为乳化剂制备的微胶囊的释放性能进行了表征。 结果表明,以相对分子质量较小的羟乙基纤维素制备的微胶囊外形规则、致密且无黏连现象。 随羟乙基纤维素黏均相对分子质量的增加所得微胶囊的平均粒径及粒径分布逐渐增大,包覆率与载药量逐渐减小。 释放性能的研究表明,采用相对分子质量较小的羟乙基纤维素制备的微胶囊的释放性能较好。  相似文献   

7.
The title compound, C4H14N2O2+·HPO42?·H2O, contains alternating interleaved layers of hydrogenphosphate and N‐(2‐hydroxyethyl)ethyl­enedi­ammonium moieties. The water mol­ecules are associated with channel‐like voids in the structure and a network of hydrogen bonds stabilizes the crystal packing.  相似文献   

8.
According to active groups synergetic catalysis principle, a novel phosphodiester receptor 1‐(N‐guanidinoethyl)‐4‐(N‐hydroxyethyl)‐piperazidine hydrochloride was firstly synthesized and the preliminary studies of its DNA cleavage activity. It is characterized and confirmed by methods as 1H NMR and 13C NMR. A “couple hardness with softness” piperazidine is designed to connect guanidinium group and hydroxyl group; The reserch was showed that the best cleaving conditions was 7.2 in pH; Cleaving DNA by the compound reaction was oxidation process that were proved through the free radicals quenches experiments; The compound can cleaved the pUC 19 DNA by phospholipid transferance was proved by BDNPP.  相似文献   

9.
通过脱氢枞醇聚氧乙烯(10)醚(DA(EO)10H)与环氧氯丙烷缩合后,再在NaOH存在下脱氯化氢得到脱氢枞氧基聚氧乙烯(10)缩水甘油醚(DA(EO)10GE),然后通过DA(EO)10GE对羟乙基壳聚糖(HECTS)的接枝制备DA(EO)10GE接枝羟乙基壳聚糖(DA(EO)10GE-g-HECTS),最后利用Genipin对DA(EO)10GE-g-HECTS进行交联,得到DA(EO)10GE-g-HECTS/Genipin水凝胶。研究结果表明:DA(EO)10GE对HECTS糖单元摩尔比的增加能提高DA(EO)10GE-g-HECTS的接枝度,并延长其与Genipin交联形成凝胶的时间;增加Genipin的用量可提高接枝产物与Genipin交联形成凝胶的能力;负载于DA(EO)10GE-g-HECTS/Genipin凝胶中的氯霉素在人工肠液中的累积释放率与时间的关系,可以很好地用Boltzmann函数描述,且提高接枝度和降低Genipin用量有利于提高药物的最终累积释放率;低接枝度DA(EO)10GE-g-HECTS经Genipin交联形成的载药凝胶,其药物释放行为符合一级动力学方程的特征。  相似文献   

10.
A new method of the synthesis of N-(hydroxyethyl)aminomethanesulfonic acid by reaction in SO2-H2NCH2CH2OH-CH2O-H2O system was developed. Compound HO(CH2)2NHCH2SO3H was characterized by XRD, IR and mass spectroscopy.  相似文献   

11.
In this study, hydroxyethyl curdlans (HeCDs) with different molecular weights were successfully fabricated. The structure and properties of the synthesized HeCDs were measured by FTIR, 13C nuclear magnetic resonance (NMR), and Raman spectroscopy and compared with curdlan. The degree of crystallinity of HeCDs was measured with X-ray diffractometry (XRD). Differential scanning calorimetry and thermogravimetric analysis were performed to determine thermal properties of HeCs. Solubility of HeCDs was tested in water, common organic solvents, and NaOH solution. Antioxidant activities of HeCs were investigated using various in vitro assay systems. The HeCDs exhibited a dose-dependent free radical scavenging activity as shown by their DPPH radical, ABTS radical and superoxide anion radical inhibition, and ferrous chelating ability and reducing power. The improved water solubility property and antioxidant activity of these curdlan derivatives could have a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical, and pharmaceutical industries.  相似文献   

12.
以过氧化苯甲酰(BPO)为引发剂, 合成了甲基丙烯酸正丁酯/甲基丙烯酸羟乙酯(BMA/HEMA)二元共聚树脂, 采用冻胶纺丝技术制备了低分子量有机液体吸附功能纤维, 利用傅里叶变换红外光谱(FTIR)和13C核磁共振波谱(NMR)、广角X射线衍射仪(WAXD)和综合热分析仪以及环境扫描电子显微镜(SEM)研究了共聚物的交联结构、纤维的结晶性能以及纤维的表面形貌, 同时研究了共聚合阶段HEMA与BMA投料比对纤维饱和吸附量的影响. 研究结果表明, 树脂大分子间不存在化学交联结构, 大分子内和大分子间存在氢键作用, 有利于物理交联结构的形成; 纤维结晶性能随着HEMA质量分数增加而减弱, 且HEMA质量分数对纤维表面形貌有较大影响; 纤维对甲苯和三氯乙烯的饱和吸附量随着HEMA质量分数增加而增大, HEMA质量分数相同时所得纤维对三氯乙烯的吸附量明显高于对甲苯的吸附量.  相似文献   

13.
Soap-free emulsion polymerization of methyl methacrylate (MMA) and hydroxyethyl methacrylate (HEMA) was carried out in the presence of colloidal nano-SiO2 particles. The effect of nano-SiO2 level on the monomer conversion, polymerization rate (Rp), and emulsion stability was investigated. The viscosity, particle size distribution of the emulsions, surface tension, and ionic conductivity of these systems were determined. Upon the introduction of the nano-SiO2 particles into this system, the Rp and monomer conversion increased and the average particle size of the P(MMA-HEMA) emulsion decreased in comparison to emulsions formed in the absence of nano-SiO2. However, the particle size distribution became broader to some degree. Scanning electron microscope observations demonstrated that the shape of these latex particles were uniformly spherical. The surface tension and ionic conductivity of the system increased significantly after polymerization, but the presence of nano-SiO2 resulted in an increase in surface tension and a decrease in ionic conductivity in comparison to the particle–free system.  相似文献   

14.
This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.  相似文献   

15.
Thermo- and UV photo-triggerable monoolein (MO) cubic phases were developed by incorporating poly(hydroxyethyl acrylate-co-coumaryl acrylate-co-octadecyl acrylate) (P(HEA-CA-ODA)) in the cubic phases. P(HEA-CA-ODA)s, for which the HEA/CA/ODA molar ratio was 98.6:0:1.4, 96.7:2.0:1.3, 96.2:2.6:1.2, 95:3.8:1.2, and 92.8:6.1:1.1, calculated on the 1H NMR spectra, were prepared by a free radical reaction. The air–water interfacial tension was inversely proportional to the CA content of the copolymer. The copolymers for which the CA content was 2.6%, 3.8%, and 6.1% exhibited their phase transition temperature in an aqueous solution in the temperature range from 25°C to 40°C. As the CA content was more, the temperature sensitivity was higher and the phase transition temperature was lower. The UV light (254 nm, 6 W)-induced dimerization degree of CA was proportional to its content in the copolymers. The release of fluorescein isothiocyanate-dextran from cubic phases containing P(HEA/CA/ODA)s was promoted by UV light irradiation, possibly due to the photo-induced collapse of the copolymer chains. The release from cubic phases incorporating copolymers, for which the CA content was 3.8% and 6.1%, was enhanced by increasing the releasing medium temperature from 23°C to 37°C, possibly due to the thermal collapse of the copolymer chains.  相似文献   

16.
The unimolecular decomposition of two radical isomers of C2H5O (CH3CH2O/ethoxy, CH3CHOH/α‐hydroxyethyl) are investigated by means of Rice–Ramsperger–Kassel–Marcus/master equation simulations in helium and nitrogen bath gases on an accurate one‐dimensional potential energy surface. For ethoxy, simulations are carried out between temperatures of 406 and 1200 K and pressures of 0.001 and 100 atm. For CH3CHOH, simulations are carried out between temperatures of 800 and 1500 K and pressures of 0.001 and 100 atm. Results are compared with available experimental data, with good agreement. The dominant product of α‐hydroxyethyl decomposition is CH3CHO + H, with C2H3OH + H and CH3 + CH2O, being minor channels. Rate coefficients are strongly dependent on temperature and pressure and are recommended with attendant uncertainty factor estimates. The relative roles of vinyl alcohol and acetaldehyde in the context of combustion chemistry are also discussed.  相似文献   

17.
《中国化学会会志》2017,64(6):612-617
We report a new, unique process for the design of poly(2‐hydroxyethyl methacrylate) (PHEMA )‐based hybrid materials, which involves the coating of PHEMA on TiO2 and TiO2 /Ag nanoparticle surface under visible light. New hybrid materials initiated under different conditions were prepared under visible light, which could be used for the theoretical design of nanohybrid materials. The hybrid materials thus prepared were characterized by Fourier transform infrared spectroscopy (FTIR ), transmission electron microscopy (TEM ), and thermogravimetric analysis (TGA ). The experimental results confirmed the successful synthesis of TiO2–PHEMA hybrid materials. Compared to other methods, the method reported here involving the direct combination of PHEMA on the TiO2 surface was simply catalyzed by visible light without the addition of initiators.  相似文献   

18.
Polymethacrylate was firstly synthesized via suspension polymerization of the monomers including butyl methacrylate (BMA) and hydroxyethyl methacrylate (HEMA) using benzoyl peroxide (BPO) as initiator. Then a mixture was prepared by mixing the synthesized polymethacrylate with the solution of HEMA and BPO and preserved in a sealed container for 24 h. Thereafter, we employed a differential scanning calorimeter (DSC) to monitor the reaction process of HEMA involved in the mixture at a constant heating rate. The viscosity changing with time for the above mixture was also measured by a rotating viscometer at 85°C with N, N-dimethylformamide (DMF) as diluting agent. Finally, the results of DSC test and viscosity test were analyzed for revealing the reaction mechanism of HEMA involved in the above mixture. Based on this analysis, we chose suitable technology parameters for the above-prepared mixture's reactive extrusion. During the reactive extrusion, the polymerization of HEMA was initiated and the generated PHEMA built an interpenetrating polymer network with the synthesized polymethacrylate by H-bonds to make the extruded resultant applicable for oil absorbent. Then the oil-absorptive capacity of the extruded resultant was characterized through oil absorbency, remaining ratio, and gel fraction, and its internal morphology was observed by polarizing microscope and field emission scanning electron microscopy.  相似文献   

19.
Sequential poly(methyl acrylate)/poly(hydroxyethyl acrylate) interpenetrating polymer networks with different poly(hydroxyethyl acrylate) contents were prepared by free radical polymerization of hydroxyethyl acrylate inside the previously polymerized poly(methyl acrylate) network. Differential scanning calorimetry on dry samples shows that the interpenetrating polymer networks exhibit phase separation, and no differences are found between the glass transition temperatures of the two phases present in the interpenetrating polymer network and those of the pure components. Thermally stimulated depolarization current experiments were used to study the influence of water sorption on the mobility of the different molecular groups in the poly(hydroxyethyl acrylate) phase of the interpenetrating polymer network. Isothermal water sorption of the interpenetrating polymer networks and pure poly(methyl acrylate) and poly(hydroxyethyl acrylate) networks is analyzed with different theories to compare the behavior of the poly(hydroxyethyl acrylate) phase in the interpenetrating polymer networks with that of the pure poly(hydroxyethyl acrylate) network. Diffusion coefficients of water in the interpenetrating polymer networks are obtained by means of dynamic sorption experiments. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1587–1599, 1999  相似文献   

20.
Vinyl mercaptoacetate S‐sulfate sodium salt (VMAS) was prepared with a yield of 74% from a reaction of vinyl chloroacetate and sodium thiosulfate. Polymerization of VMAS with 2‐hydroxyethyl acrylate (HEA) in the presence of ammonium persulfate and N,N,N ′,N ′‐tetramethylethylenediamine afforded a colorless copolymer bearing the S—SO3 Na+ group in 3.2–4.3 mol‐% and having a MW of 2.4–13×104. The polymer was water‐soluble but, upon treatment with an oxidizing agent, was transformed quickly into a water‐tolerant material. It again became water‐soluble on the addition of a reducing agent. The unique solubility alternation was explained by the formation and fission of S—S bond crosslinking in the polymer.  相似文献   

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