基于动态硼酸酯键聚合物的构筑和应用研究进展

基于动态硼酸酯键构筑的聚合物有一定的自修复能力和对刺激的多重响应性,能够通过诱导材料内部物理/化学结构的拓扑重组并以此来响应生物信号的变化。本文综述了基于水解/再酯化、二醇硼酸酯之间的酯交换和硼酸酯之间的酯交换3种不同的硼酸酯酯交换机制构筑的多种天然/非天然高分子材料;通过传统共价键和硼酸酯动态共价键协同作用设计更加稳定的四面体硼酸盐结构来解决硼酸酯基聚合物稳定性较差的策略;硼酸酯基聚合物在生物医药、传感器和可回收材料等多领域的应用潜力。重点介绍了硼酸酯键与其它动态键协同作用制备理想的聚合物材料,如水凝胶、有机凝胶、液晶材料和可回收纳米材料等。     

新型硼酸酯键合剂与HMX的键合作用

合成了一种带氨基的硼酸酯键合剂,用傅里叶变换红外光谱对硼酸酯进行了结构表征。采用红外光谱(IR)和X射线光电子能谱(XPS)技术,分析了含硼键合剂与HMX晶体间的界面相互作用。结果表明,硼酸酯键合剂中的B原子和NH2基团与HMX的NO2基团间分别产生了配位键合及诱导作用,NO2不对称伸缩振动峰出现3cm-1的位移,B1s向低结合能端移动0.8eV,NH2基的N1s也产生0.8eV的移动,证实了该含硼键合剂作为HMX键合剂的可行性。     

一种硼酸酯动态交联环氧树脂的合成与性能

利用巯基与环氧的点击反应,向环氧体系中引入二醇结构,并通过硼酸酯键对其进行交联,制备了一系列不同流变性能和玻璃化转变温度的可塑环氧树脂材料。研究了不同的配方对材料性能的影响,结果表明通过改变交联剂与动态链结的比例,体系的流变性能可以被调控;另一方面,改变软硬环氧组分的比例可以使材料的玻璃化转变温度在14.6~36.5℃之间调节。制备了该可塑环氧树脂与密胺通孔泡沫的复合材料,该材料具备良好的快速自黏结性能。材料断裂后,在10 s内即可达到最大黏结强度,且经多次拆卸-黏结循环后,黏结强度可以保持在约0.06 MPa。     

硼酸酯类键合剂研究进展

介绍硼酸酯类键合剂的发展现状,分析硼酸酯类键合剂在固体推进剂中的作用机理及其在应用中存在的问题,总结了几种典型的合成方法,对其优缺点进行了对比,并就该类键合剂的研究方向提出一些建议。     

基于动态硼酸酯键/氢键的自修复水凝胶的制备及性能

通过4-(溴甲基)苯基硼酸(PBA)和1-乙烯基咪唑(IL)的烷基化反应制备了苯硼酸离子液体(PBA-IL)单体。在2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)氧化纳米纤维素(CNF)的存在下，通过丙烯酰胺(AM)和PBA-IL的一步聚合反应，制备了一种具有半互穿网络结构的自修复导电水凝胶(PAM/PBA-IL/CNF)。通过1HNMR对PBA-IL的化学结构进行表征；通过FTIR、XPS、SEM对水凝胶的化学结构和物理形貌进行表征，并测试了水凝胶的拉伸性能、自修复性能和导电性能。结果表明，PBA-IL单体和水凝胶成功制备，且水凝胶具有典型的多孔结构。PAM/PBA-IL3/CNF水凝胶[3代表PBA-IL含量为30%，以AM、PBA-IL、CNF悬浮液、N,N’-亚甲基双丙烯酰胺(MBA)溶液、过硫酸铵(APS)的总绝干质量为基准]的断裂应力为335.1 kPa、断裂伸长率为1969.5%、断裂能为12.1 kJ/m²、自修复效率为95.43%(150 min)、电导率为6.38 mS/cm。     

黄原胶的性能及应用

黄原胶又名苫屯胶、甘兰黑腐病黄单胞菌胶。是以葡萄糖为原料,通过以甘兰叶面上离析的黄杆菌属的 Campestris 菌发酵而生产的一种生物胶。50年代后期自 USDA(即美国农业部)发现以来,由于其特殊性能而引起人们的注目。现已有工业化生产,广泛应用于各种水系液流特性的改性方面,应用范围逐年扩大。     

pH敏感性硼酸酯键及其递药系统的研究进展

由于肿瘤细胞的高代谢率导致供氧不足,肿瘤细胞在低灌注区的细胞外间隙与周围正常组织细胞相比具有高酸性,因此具有pH敏感性的纳米载药系统被广泛应用于癌症治疗中。硼酸酯键是一种可逆的pH敏感性的化学键,在酸性环境中此键可以断裂,将其制备成具有pH响应性硼酸酯键的纳米载药系统,可以达到pH敏感性控制释放药物的目的。     

黄原胶的性能及其应用

论述黄原胶的性质，生产工艺，技术关键，讨论了黄原胶的发酵设备，生产过程中分离，干燥，粉碎等工序。     

黄原胶的性能与应用

重点介绍了以玉米淀粉为原料生物合成黄原胶的发酵工艺以及产品分离提纯工艺；介绍了黄原胶的分子结构及其假塑流变性、对酸碱稳定性、悬浮乳化性、增稠剂的协效性等性能，并介绍了其在食品、石油和纺织等领域的应用；最后对目前国内外黄原胶生产状况作了调查分析。     

黄原胶的性能与应用

重点介绍了以玉米淀粉为原料生物合成黄原胶的发酵工艺以及产品分离提纯工艺；介绍了黄原胶的分子结构和其假塑流变性、对酸碱稳定性、悬浮乳化性以及与增稠剂的协效性等性能，并介绍了其在食品、石油和纺织等领域的应用；最后对目前国内外黄原胶生产状况作了调查分析。     

黄原胶水凝胶制备的研究进展

黄原胶水凝胶具有亲水性强、无毒、可降解及生物相容性好等优点,常作超吸水性树脂、药物载体和微胶囊。对黄原胶水凝胶的制备方法进行了综述,并对其发展进行展望。     

凹凸棒黏土/黄原胶接枝改性高吸水性树脂的制备

以丙烯酸(AA)、丙烯酰胺(AM)为单体对黄原胶(XG)进行接枝改性,再以N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸铵(APS)为引发剂,加入凹凸棒黏土,采用溶液聚合法合成了一种新型复合高吸水性树脂。通过单因素试验研究了AA中和度、交联剂用量、引发剂用量、反应温度和凹凸棒黏土用量等因素对该树脂吸水(吸盐水)性能的影响,利用傅里叶红外光谱(FT-IR)仪、热重分析(TGA)仪对其结构和热性能进行了表征。结果表明:制备高吸水性树脂的最佳工艺条件为AA中和度70%,反应温度70℃,w(交联剂)=0.06%,w(APS)=1.0%,w(凹凸棒黏土)=5%;在最佳工艺条件下制备的高吸水性树脂,其最大吸水倍率、吸盐水倍率分别为827、109 g/g。     

Effect of storage time on the mechanical and microstructural properties of bigels based on xanthan gum and castor oil

As biphasic systems bigels are formed by hydrogels and organogels. Given their characteristics, they have been studied in food, pharmaceutical and cosmetic applications for bioactives delivery. The rheological characteristics and amount used of the individual structured systems influence the final properties; thus, the objective of this work was to evaluate the effect of the proportion of castor oil organogel, the concentration of organogelator, and the storage time in the mechanical and microstructural properties of bigeles. Bigels were prepared from structured castor oil organogels with monoacylglycerides at concentrations of 6% (MOG) and 6.5% (HOG) wt/wt, and hydrogels with 2% wt/wt xanthan gum (HG) at three organogel/hydrogel ratios 15 of 85, 30 of 70, and 45 of 55. Bigels were characterized by optical microscopy with polarized light filter, centrifugal stability, texture, and rheology for 60 days. The increase in the proportion of organogel favors the mechanical response (k, G₀, and firmness) of bigels. The high viscosity of castor oil slows down the structuring of organogel droplets, showing an improvement in its mechanical properties after 15 days of its preparation. The increase in the organogelator concentration is significant in the bigels with 30% and 45% proportions of organogel in the rheological tests. By using HOG in the formation of bigels, higher values for G₀ and k were obtained, as well as higher centrifugal stability compared with bigels formed from MOG. The rheological and microstructural behavior of bigels can be modified according to their application by varying the proportions of organogel/hydrogel and the concentration of the organogelator.     

Biodegradable films based on chitosan,xanthan gum,and fish protein hydrolysate

The aim of this study was to develop films based on chitosan, xanthan gum, and protein hydrolysate of Whitemouth croaker (Micropogonias furnieri), evaluating their antioxidant activity and also their mechanical, physical, structural, morphological, thermal, and barrier properties. The mixture of xanthan gum and protein hydrolysate promoted some changes in chitosan films. The addition of xanthan gum increased tensile strength and changed the color parameters of films. The addition of Whitemouth croaker protein hydrolysate increased the antioxidant activity of the films. However, higher concentrations of hydrolysate tend to increase moisture and decrease their tensile strength. All films had homogeneous structure, with no phase separation and fissures. Significant differences in water solubility and water vapor permeability were not observed by the addition of xanthan gum and protein hydrolysate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44899.     

黄原胶与丙烯酰胺接枝共聚反应的研究

以过硫酸铵为引发剂,在氮气保护下,研究了黄原胶与丙烯酰胺的接枝共聚反应。考察了单体浓度、引发剂浓度、反应温度和反应时间等因素对接枝率及接枝效率的影响,探讨了过硫酸铵引发黄原胶接枝丙烯酰胺共聚反应的基本规律。采用红外光谱、X射线粉末衍射对接枝共聚物的结构进行研究,用热重分析法表征了产物的热性能,并初步探讨了接枝机理。结果表明,过硫酸铵能有效地引发黄原胶与丙烯酰胺的接枝共聚反应,并且接枝率和接枝效率随单体浓度、引发剂浓度、反应温度的变化出现极大值,随反应时间的延长不断上升,直至基本不变。     

含硫、氮的硼酸酯添加剂的制备及摩擦学性能

在催化剂存在下,通过酯化反应制备了含二正丁基二硫代氨基甲酸结构的有机硼酸酯(SNBC)。通过四球磨损试验机考察SNBC在100N基础油中的摩擦学性能,采用扫描电子显微镜(SEM)和能谱仪(EDS)分别分析磨损表面形貌和磨斑表面元素组成,通过水解稳定性实验测定硼酸酯的水解稳定性。结果表明,合成的硼酸酯(SNBC)具有较好的水解稳定性,同时SNBC作为润滑油添加剂与二烷基二硫代磷酸锌(ZDDP)相比具有较好的减摩性能,在低添加量下能显著提高基础油的极压性能。SEM分析表明,SNBC能有效减轻钢球摩擦副表面的擦伤和磨损。     

Effect of xanthan gum on enhancing the foaming properties of whey protein isolate

The foaming properties of whey protein isolate (WPI) in the presence of xanthan gum (XG) were investigated. XG dispersion did not exhibit any foaming properties. The optimal foaming overrun (FO), or the amount of air incorporated into the dispersion, was obtained from the dispersion of 5% WPI and 0.05% XG at 949%. This WPI-XG dispersion had a significantly higher overrun than that of WPI (868%) or egg white (879%) (P<0.05). Optimal foam stability (FS) of 216 min was obtained at 5% WPI and 0.2% XG; however, the overrun was reduced slightly (844%). XG increased stability to 15 times that of WPI alone. The overrun of 5% WPI plus 0.05% XG was further increased to 1343% when 1 M NaCl was added (P<0.05). However, FS (51 min) was significantly reduced. A significant increase in the FO of 5% WPI plus 0.05% XG (1081%) was observed when pH was adjusted to 5.0 with no significant change in FS (56 min) (P<0.05). The FO (1457%) was significantly increased (P<0.05) when the WPI-XG was heat treated (55°C for 5 min). WPI-XG dispersions at acidic pH and temperatures below 85°C have a variety of potential applications in products such as protein beverages, angel food cake, and unique infant formulas.     

含酯基双子季铵盐阳离子表面活性剂的合成及性能

分别以氯乙酸辛酯 ,氯乙酸十二醇酯、氯乙酸十四醇酯和四甲基乙二胺反应合成了相应的含酯基双子季铵盐阳离子表面活性剂化合物 (Ⅰ～Ⅲ )。滴体积法测定化合物Ⅰ～Ⅲ的表面张力和cmc。γcmc分别为2 7 3 1、 3 3 73和 3 4 0 1(mN/m) ,cmc分别为 5 0 1× 10 -3 、 3 98× 10 -3 和 3 16× 10 -3 (mol/dm3 )。     

Kinetic interpretation of influence of sodium chloride concentration and temperature on xanthan gum dispersion flow model

The present study derives a fixed‐concentration (0.4%) xanthan gum dispersion flow model for different molar concentrations of sodium chloride (0–0.25M) and different temperatures (20–70°C). The Ostwald–de Waele model is used in all cases. A temperature rise reduces the shear‐thinning characteristics of the systems, although the power law index is much less sensitive to changes in temperature when NaCl is added, even in very small amounts. The lowest consistency values correspond to the dispersions formulated in the absence of salt, the highest values are observed for molar values of ≥0.15, and there are decreases in consistency upon raising the temperature in all cases. The viscous behavior of the dispersions is interpreted using the Eyring equation. The activation energy and the free volume decrease when the shear rate is increased. The addition of NaCl, regardless of the molar concentration involved, provokes an important decrease of the activation energy. The free volume is independent of the molar concentration of NaCl for molar values >0.025. These results are related to the structure of the dispersions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 332–339, 2002