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。     

巯基葡聚糖凝胶的制备及其对微量重金属离子吸附性能的研究

葡聚糖凝胶(DG)是一种交联的右旋糖苷,一般用作分子筛凝胶色谱的固体填充剂,分离不同分子量的有机化合物。1981年,林滋彦等人在DG骨架上接入黄原酸基,获得了对重金属离子具有良好吸附性能的黄原酸基凝胶。我们利用DG上的羟基与巯基乙酸的酯化反应,在DG骨架上引入了-C-CH_2-SH 基团,制备出巯基葡聚糖凝胶(SDG)。这种凝胶,目前在文献中似未见报导。研究表明,SDG的巯基含量高于黄原酸基凝胶     

不同浓度明胶水凝胶用于3D生物打印的初步研究

目的:利用天然高分子材料明胶的生物学性能及交联特性,构建不同浓度的可用于3D生物打印的生物墨水,并对其进行制备,表征与分析,为之后的生物打印提供材料基础。方法:基于以往研究,制备不同浓度的甲基丙烯酸酐(MA)改性明胶水凝胶,分别进行MA改性明胶水凝胶制备、溶胀性能、力学性能、营养液渗透、3D生物打印实验,以此来确定明胶水凝胶的物理特性及生物学特性。结果:在浓度为10%～20%的MA改性的明胶水凝胶范围内,浓度越低,水凝胶越透明,透光性越好;溶胀性能实验表明,在浓度为10%～20%的MA改性的明胶水凝胶范围内,浓度越高,溶胀率越低;力学性能实验表明,在浓度为10%～20%的MA改性的明胶水凝胶范围内,浓度越大,杨氏模量越大;营养液渗透实验表明,在浓度为10%～20%的MA改性的明胶水凝胶中,浓度越低,营养液渗透的越快。3D生物打印表明利用明胶水凝胶可以打印出预先设计的几何形状,且经过紫外光交联后,能够形成具有一定机械强度的水凝胶胶体。结论:15%的MA改性明胶水凝胶具有优良的溶胀性能,力学强度以及适合的孔隙率,并具备3D打印能力。     

耐温抗盐型黄原胶体系在油田开发中的应用研究进展

论述了黄原胶水溶液的耐温抗盐机理以及流变特性,并针对黄原胶的生物稳定性差、热氧降解快、成本高等缺点,详细综述了黄原胶的添加剂、交联体系和疏水改性研究现状,以期促进耐温抗盐型黄原胶体系在油田开发中推广使用。     

以黄原胶为凝胶浴制备GO/MWCNTs/PVP/PVDF抗污染膜

以聚偏氟乙烯(PVDF)为原料,氧化石墨烯(GO)和多壁碳纳米管(MWCNTs)为添加剂,黄原胶(XG)作为凝胶浴,通过非溶剂相转化(NIPS)法制备改性膜.采用傅里叶红外光谱(FT-IR)、扫描电镜(SEM)和接触角等表征手段,探究了组合添加剂对PVDF膜结构和亲水性能的影响.结果表明:在实验以黄原胶(XG)作为凝胶...     

淀粉衍生物与黄原胶、卡波姆复配凝胶的制备及其在护肤品中的应用研究

淀粉衍生物是一种来源广泛、价格低廉且安全性高的凝胶剂。将淀粉衍生物与黄原胶或仁波姆复配使用,发挥两者间的协同互补作用,既可减少原料用量,又可扩大淀粉和胶体的应用范围。介绍了淀粉和黄原胶的复配机理;以黄原胶及卡波姆为原料．分别加入不同浓度、不同改性方式的淀粉衍生物,研究淀粉胶体复配凝胶的黏度特性;并对优选的复配凝胶进行感官评测。结果表明,水薯淀粉衍生物和冷溶马铃薯淀粉在所选淀粉中黏度较高,较适宜与胶体制备复配凝胶;当黄原胶浓度为1．0％时,加入2．2％～2．4％的小薯淀粉衍生物或2．8％的冷溶马铃薯淀粉;或当骨波姆浓度为0．1％时,加入《1．8％～1．1％的水薯淀粉衍生物或1．6％的冷溶吗铃薯淀粉。均可得到与市告护肤凝露黏度相同的凝胶;感官评测表明．淀粉／胶体复配凝胶具有良好的质感和吸收效果。     

黄原胶接枝聚丙烯酸水凝胶的合成及对亚甲基蓝阳离子染料的吸附性能

以黄原胶和丙烯酸为原料,N,N'-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,在水溶液中合成黄原胶接枝聚丙烯酸(XG-g-PAA)水凝胶,考察了pH值、吸附时间、阳离子染料亚甲基蓝(MB)的初始浓度等对水凝胶吸附性能的影响,研究了水凝胶对MB的等温吸附行为。结果表明,当pH值大于5.0时,XG-g-PAA水凝胶对MB有较大的吸附量;水凝胶吸附平衡时间为5 h;室温下随着MB初始浓度的增大,水凝胶对MB的吸附量较大;水凝胶对MB的吸附行为符合Freundlich吸附等温模型,其相关系数为0.985 54,吸附过程以化学吸附为主。     

不溶性淀粉黄原酸酯的制备及其在含Cr(Ⅵ)废水处理中的应用

以玉米淀粉为原料、环氧氯丙烷为交联剂制备交联淀粉,再进行黄原酸化反应制备不溶性淀粉黄原酸酯(ISX),并将其用于含Cr(VI)废水的处理。考察了环氧氯丙烷的用量、二硫化碳的用量、氢氧化钠的用量、黄原酸化时间、稳定剂的用量等制备条件对所制备的ISX处理含Cr(VI)废水效果的影响。最佳的制备条件为:玉米淀粉15g,交联剂2.2mL,氢氧化钠2.5mL,二硫化碳2.5mL,硫酸镁3g,黄原酸化反应3h。合成的淀粉黄原酸酯对质量浓度为50mg/L的含Cr(VI)废水的去除率达到99.6%以上。     

酚醛基炭气凝胶的研究进展

炭气凝胶是一种多孔纳米炭材料,具有低密度、高孔隙率、高比表面积、优异的导电性和良好的成型性能等优点,是炭材料研究的热点和重要方向。本文旨在通过阐明酚醛基炭气凝胶的制备原料和制备工艺的发展过程,从而突出未来酚醛基炭气凝胶的发展方向。基于此,本文首先重点介绍了酚醛基炭气凝胶的制备方法,主要包括溶胶-凝胶化、干燥以及炭化过程三个最主要的步骤;进而详述了以三种不同的前体,即间苯二酚、苯酚、生物质单宁/木质素分别制备酚醛基炭气凝胶的方法及其优缺点;接下来对酚醛基炭气凝胶作为吸附材料（气体吸附/液体吸附）的吸附量以及在电化学储能以及其他领域的应用进行了综述;最后对酚醛基炭气凝胶未来的研究方向和发展前景进行了总结和展望。文章指出,传统的以间苯二酚为原料辅以超临界干燥的方法制备的酚醛基炭气凝胶,原料成本较高,反应条件苛刻,实际生产应用受限;以苯酚取代间苯二酚,亦或是采用冷冻干燥等方法改进其制备工艺,可以大幅度降低原料和生产成本;但未来的发展方向和重点将是绿色、可再生的生物质原料（单宁、木质素、腰果酚等）及复合气凝胶材料的研发。因此,酚醛基炭气凝胶在未来的发展还需要进一步改进其制备工艺和方法,拓宽其原料来源,从而提高性能,扩大应用领域。     

天然高分子亲水性凝胶材料在竹醋液中 溶胀度的初步研究

测定了壳聚糖、黄原胶、海藻酸钠3种天然高分子亲水性凝胶材料在竹醋液中的溶胀度。探讨了温度、pH值对其溶胀度和溶胀速率的影响。结果表明在20~40℃ 范围内,3种凝胶的溶胀度和溶胀速率随着温度的升高而增加;在不同pH值的竹醋液中,壳聚糖和黄原胶的溶胀速率十分相近,而且黄原胶比壳聚糖更稳定。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.