单分子膜研究的方法及现状

单分子膜一般是将两亲性物质溶解在铺展溶剂中制成铺展溶液,然后铺展在底液上而得的。在其性质的研究中,测定表面压－面积关系曲线是最基本、也是最重要的一种研究手段。但是,仅有表面压－面积曲线所能了解的信息是远远不够的,因此必须结合另一些手段进行研究,测定表面粘度就是其中很重要的一种。而随着现代光谱仪器的更新、发展,光学方法已日益成为单分子膜研究的一个重要途径。     

C16OH／AEO-3混合分子膜抑制水分蒸发的研究

探讨了C16OH／AEO-3复配比例、温度、时间、环境因素等对分子膜抑制水分蒸发效果的影响。研究结果表明,当温度为25℃,膜表面浓度为8．0×10^2g／m^2时,C16OH的抑制率最高仅为35％,引入AEO-3后,当C16OH／AEO-3的复配比例为7：3时,抑制率最高可达60％以上。室外实验表明,混合膜在膜表面浓度为4．0×10^-1g／m^-2时,15d后仍有一定的抑制效果,抑制率依旧保持在30％以上。此外,在15℃-40℃的温度范围内,混合膜的抑制率高于C16OH,显示出更好的抑制水分蒸发能力。透气性测试结果表明,C16OH和混合膜均不妨碍气水界面的氧气交换。分子膜的AFM图像显示,混合膜能形成比C16OH更为凝聚的分子膜,产生更为理想的抑制水分蒸发效果。     

C_(16)OH/AEO-3混合分子膜抑制水分蒸发的研究

探讨了C16OH/AEO-3复配比例、温度、时间、环境因素等对分子膜抑制水分蒸发效果的影响.研究结果表明,当温度为25 ℃,膜表面浓度为8.0×10-2 g/m2时,C16OH的抑制率最高仅为35%,引入AEO-3后,当C16OH/AEO-3的复配比例为7 ∶ 3时,抑制率最高可达60%以上.室外实验表明,混合膜在膜表面浓度为4.0×10-1 g/m2时,15 d后仍有一定的抑制效果,抑制率依旧保持在30%以上.此外,在15 ℃～40 ℃的温度范围内,混合膜的抑制率高于C16OH,显示出更好的抑制水分蒸发能力.透气性测试结果表明,C16OH和混合膜均不妨碍气水界面的氧气交换.分子膜的AFM图像显示,混合膜能形成比C16OH更为凝聚的分子膜,产生更为理想的抑制水分蒸发效果.     

铺展溶剂对气／水界面上C16OH不溶膜的影响

文章探讨了不同铺展溶剂对十六醇（C16OH）不溶膜在空气／水界面上的性能的影响。测试了铺展系数和成膜功,π-t等温线和r-t等温线,并用AFM观察了不同溶剂下的C16OH不溶膜形貌。结果表明以石油醚（30℃～60℃）为铺展溶剂的不溶膜铺展效果最好,铺展15min后,π就达到25mN／m以上,30min以后,π趋于稳定。且石油醚（30℃-60℃）在不溶膜中的残留最少,抑制水分蒸发的效果最好。不溶膜的AFM图像显示,以石油醚（30℃～60℃）作为铺展溶剂的不溶膜结构更紧密,凝聚性更好,膜的缺陷更少,因此抑制水份蒸发的效果更好。     

铺展溶剂对气/水界面上C_(16)OH不溶膜的影响

文章探讨了不同铺展溶剂对十六醇(C16OH)不溶膜在空气/水界面上的性能的影响.测试了铺展系数和成膜功,π-t等温线和r-t等温线,并用AFM观察了不同溶剂下的C16OH不溶膜形貌.结果表明以石油醚(30℃～60℃)为铺展溶剂的不溶膜铺展效果最好,铺展15 min后,π就达到25 mN/m以上,30 min以后,π趋于稳定.且石油醚(30℃～60℃)在不溶膜中的残留最少,抑制水分蒸发的效果最好.不溶膜的AFM图像显示,以石油醚(30℃～60℃)作为铺展溶剂的不溶膜结构更紧密,凝聚性更好,膜的缺陷更少,因此抑制水份蒸发的效果更好.     

不同流体界面上大豆11S球蛋白吸附膜膨胀黏弹性的比较研究

采用轴对称滴形分析法(ADSA)检测了空气/水、正十二烷/水和大豆油/水界面上不同浓度(0.001%~0.1%)的大豆11S球蛋白吸附膜的表面膨胀黏弹性随吸附时间的变化。研究表明,在体相蛋白溶液pH8.0和离子强度0.05mol/L的恒定条件下,随着吸附时间的延长,表面膨胀弹性增大,膨胀弹性明显大于膨胀黏性。从表面流变学的角度分析,空气/水和大豆油/水界面上大豆11S球蛋白吸附膜实际上是弹性的,膨胀弹性随液滴体相蛋白浓度的增加而增大,受界面类型的影响很大。空气/水界面上吸附膜的膨胀黏弹性最大,而大豆油/水界面上吸附膜的膨胀黏弹性最小。     

分子蒸馏单月桂酸甘油脂的研制

纯度在90%以上的单月桂酸甘油脂(GML)具有优良的乳化和防腐功效。由于GML是热敏性难分离物质,所以需要采用分子蒸馏(MolecularDistillation)提取高纯度的GML产品。本文从空气残压、蒸馏温度、冷凝面温度、料液流速等几个方面着手,结合分子平均自由程理论,确定了GML粗产品的分子蒸馏工艺。     

分子蒸馏单月桂酸甘油脂的研制

纯度在90%以上的单月桂酸甘油脂(GML)具有优良的乳化和防腐功效。由于GML是热敏性难分离物质,所以需要采用分子蒸馏(MolecularDistillation)提取高纯度的GML产品。本文从空气残压、蒸馏温度、冷凝面温度、料液流速等几个方面着手,结合分子平均自由程理论,确定了GML粗产品的分子蒸馏工艺。      

基于分子交联的蛋白膜性能改良技术的研究进展

蛋白膜由于具有无毒害、可降解、绿色环保、可延长食品保质期、提供营养等优点,在可食膜研究领域具有重要地位。如何改善其相对较弱的机械强度以及某些不足的阻隔性能,是研究者长期以来一直关注并将持续关注的问题。本文首先阐述了蛋白膜的成膜机制、性能指标,接着重点对基于分子交联的蛋白膜性能改良技术,包括物理交联、化学交联、酶法交联以及物理能交联等进行综述,最后对蛋白膜交联的意义和发展趋势进行了展望。     

聚氧化乙烯对大豆分离蛋白静电纺丝影响的研究

初步研究了聚氧化乙烯(PEO)对大豆分离蛋白(SPI)静电纺丝的影响,分析了SPI/PEO共混配比和相应过程参数(电压、溶液流速和接收距离)对共混溶液性质和静电纺丝可纺性的影响,通过扫描电镜对所得纤维形态进行了表征。结果表明,随着溶液中PEO含量的增加,体系的粘度增大,电导率下降,得到的电纺纤维形态均一,直径分布较窄,明显改善了SPI的可纺性;电压、溶液流速和接收距离均对电纺纤维的形成及形貌有一定的影响,三者过高或过低都会导致纤维形貌的变化,形成串珠或颗粒。10wt%SPI/PEO共混溶液的最佳电纺共混比为70/30,电压为15kV,接收距离为10cm,溶液流速为1.5mL/h。      

Nanofibrous web quality in dependence on the preparation of poly(ethylene oxide) aqueous solutions

The method of preparation of polymer solutions significantly influences the quality of the corresponding electrospun nanofibrous webs. However, this factor is often ignored, and in a majority of presentations concerning the electrospinning process, the applied method is not mentioned. This paper compares the influence of magnetic stirring, vibrational shaking and ultrasonication on a solution of poly(ethylene oxide) in distilled water. Along with the methods of preparation, other parameters were altered such as concentration, intensity of mixing and molecular weight. The best results from the viewpoint of electrospinning were achieved with moderate magnetic stirring.     

Effect of polymer concentration on electrospinning of hydroxypropyl-β-cyclodextrins/PEO nanofibres

Hydroxypropyl-β-cyclodextrin (HP-β-CD) is a β-cyclodextrin (β-CD) derivative which is toxicologically harmless to mammals and other animals. In this study, HP-β-CD is electrospun from an aqueous solution by blending with poly(ethylene oxide) (PEO). The aqueous solutions containing different HP-β-CD/PEO blends (50:50–90:10) with varying concentrations (4–12 wt.%) were electrospun at 1 ml/h feed rate, 12 cm working distance and 7 kV applied voltage. The morphology of the nanofibres was investigated by scanning electron microscope. The average diameter of the nanofibres was measured using ImageJ software. It was found from the results that the uniform nanofibres with an average diameter of 264, 244 and 236 nm were obtained from 8 wt.% solution of 50:50, 60:40 and 70:30 HP-β-CD/PEO blends, respectively. The average diameter of the fibre decreases with increasing HP-β-CD/PEO ratio. However, higher proportion of HP-β-CD (i.e. above 70:30 HP-β-CD/PEO blend) in the spinning solution increases the possibility of creating more beads in the fibres. Although the polymer concentrations have not shown a significant effect on fibre diameter, the 8 wt.% solution of 50:50 HP-β-CD/PEO yielded uniform smooth fibres with the narrowest distribution of the diameters. As the aim of this study is to maximize the HP-β-CD content in the fibre, the blend ratio of 70:30 HP-β-CD/PEO and solution concentration of 8 wt.% were optimized to obtain smooth HP-β-CD/PEO nanofibres.     

PET固相缩聚反应的影响因素

ＰＥＴ的固相缩聚是将低分子量预聚体加热到熔点和玻璃化温度之间,切片内部缩聚反应持续进行,分子量不断提高,乙二醇、水等副产物借助真空或惰性气体带出反应器,固相缩聚中包括酯化反应、酯交换反应以及小分子的扩散过程。表观反应速率受预聚体颗粒形状大小、结晶度、惰性气体、反应温度、反应时间等因素的影响,其中反应温度、惰性气体中小分子副产物含量两个主要影响因素,应合理选择并控制这些参数,以利于生产由高质量的ＰＥ     

聚(环三磷腈-间苯三酚)微球的制备及其在聚酯阻燃中的应用

为提高聚对苯二甲酸乙二醇酯(PET)的阻燃性能,以六氯环三磷腈(HCCP)和间苯三酚为原料制备聚(环三磷腈-间苯三酚)(PCTP)微球,将PCTP微球作为阻燃剂通过物理共混方式添加到PET中制备PET/PCTP复合材料,并借助热重分析仪、锥形量热仪、热重-红外联用仪、极限氧指数仪和万能材料试验机等对PET/PCTP体系的热稳定性、阻燃性能、力学性能和阻燃机制进行分析。结果表明:向PET中添加质量分数为2% 的PCTP微球所制备的PET/PCTP2.0 复合材料,其极限氧指数(LOI)从24.4%增加到31.1%,且UL-94 达到V-0水平;相较于PET,PET/PCTP2.0复合材料的峰值热释放速率和总热释放量均显著降低(分别下降28.7%和17.7%),断裂强力下降13.3%,仍保持较好的力学性能;PET/PCTP复合材料在燃烧过程中可快速生成致密连续的炭层,隔绝可燃物内外的热量交换,同时释放出CO₂等不燃气体,稀释PET基材周围的氧气从而实现阻燃。     

Characterization of virgin and recycled poly(ethylene terephthalate) (PET) fibers

In this study, we compared the properties of recycled poly(ethylene terephthalate) (PET) fibers and virgin PET fibers. All these experiments present the differences or similarities between them on surface morphology, mechanical properties, and internal fiber structure. The results show that the surface morphology of both PET fibers is similar. According to the tests on mechanical properties, it can be observed that recycled PET fibers have a higher tensile strength and greater elongation at break. The recycled fiber has a higher degree of crystallinity while with the smaller average crystallite size based on the X-ray diffraction data. In polarized attenuated total reflectance infrared technique, the virgin fibers have a better performance than the recycled ones in orientation. Fourier Transform Infrared spectrum analysis indicates that both kinds of fibers have the similar representative groups.     

Insulinoma cell line (MIN6) adhesion and spreading mediated by Arg-Gly-Asp (RGD) sequence conjugated in thermo-reversible gel

We have functionalized gels with a putative cell-binding (-Arg-Gly-Asp-) (RGD) domain in an effort to regulate mammalian cell behavior in cells entrapped with gel. Adhesion molecules composed of Gly-Arg-Gly-Asp-Ser (GRGDS) peptides and cell recognition ligands were inculcated into thermo-reversible hydrogel composed of N-isopropylacrylamide, with a small amount of succinyl poly(ethylene glycol) (PEG) acrylate (MW 2000) used as a biomimetic extracellular matrix (ECM). The GRGDS-containing p(NiPAAm-co-PEG) copolymer gel was studied in vitro for its ability to promote cell spreading and to increase the viability of cells by introducing PEG spacers. Hydrogel lacking the adhesion molecules proved to be a poor ECM for adhesion, permitting only a 20% spread of the seeded cells after 10 d. When PEG spacer arms, immobilized by a peptide linkage, had been integrated into the hydrogel, conjugation of RGD promoted cell spread by 300% in a 28-d trial. In addition, in a serum-free medium, only GRGDS peptides conjugated with the spacer arm were able to promote cell spread.     

高分子量壳聚糖∕聚氧乙烯复合纳米纤维的制备

利用3%的高分子量壳聚糖（HCS）与聚氧化乙烯（PEO）以3:1的比例溶解在50%的乙酸水溶液中;使用浓度高于临界胶束浓度的不同表面活性剂改善溶液的可纺性;借助静电纺丝技术制备了HCS/PEO复合纳米纤维。采用扫描电子显微镜（SEM）对复合纳米纤维形貌进行表征;采用傅立叶红外光谱（FTIR）方法研究了HCS、PEO及表面活性剂的相互作用;采用单纤维强力仪测试薄膜力学性能的变化;评价使用戊二醛处理后的HCS、PEO复合纳米纤维膜的力学性能。实验结果表明PEO增强了HCS的成纤性。以胶束形式存在的表面活性剂;通过改变混合溶液中分子间的结合方式;降低溶液粘度;提高了可纺性能。戊二醛交联处理提高了复合纤维的强度。特别是阴阳离子混合表面活性剂的使用;纤维形貌最好;强度明显提高。