聚丙烯腈分离膜改性研究进展及其应用

综述了聚丙烯腈分离膜改性研究新进展,包括表面接枝、复合、共聚合、聚合物化学反应、分子印迹法等,着重介绍了改性聚丙烯腈分离膜在渗透蒸发、生物大分子的固定化、徽滤、超滤、气体分离、人工脏器以及模拟生物膜等方面的应用。     

芳香族聚酰胺纤维改性技术进展

分析了芳香族聚酰胺纤维目前存在的问题,在55篇参考文献的基础上,综述了间位芳香族聚酰胺、对位芳香族聚酰胺的各种改性技术的进展,探讨了芳香族聚酰胺纤维改性技术的发展前景.     

Preparation and Modification of Chitin-Based Fibers

Spinning solutions of chitin were modified with polyvinylpyrrolidone, methyl cellulose, and sulfite cellulose. The resulting systems were used for preparing fibers by the wet formation method. The deformation and strength characteristics of these fibers were determined, and their X-ray diffraction analysis was carried out. The influence of the modifying additives on the structure and characteristics of the systems prepared was explained.     

硅烷改性含氟丙烯酸酯共聚物乳液

利用正硅酸乙酯(TEOS)水解和长链烷基三甲氧基硅烷(WD-10)的硅烷偶联剂作用,以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)和甲基丙烯酸十二氟庚酯(DFMA)为原料的核壳型含氟丙烯酸酯聚合物乳液进行原位复合改性。通过XRD、FTIR、SEM-EDX、TEM、RGD、DSC、NMR等测试技术分析和讨论了合成的聚合物乳液的乳胶粒子结构和形态,以及TEOS和WD-10含量对改性的聚合物乳液稳定性和对聚合物成膜性的影响。结果表明,TEOS水解产生了S iO2,核壳型结构粒子基本呈现圆形分布,粒径为40~50 nm。TEOS的最佳质量分数为3.1%~3.8%,WD-10含量宜控制在TEOS质量分数为0.9%~0.95%之间。     

含环氧基的丙烯酸酯共聚物改性环氧树脂

合成了一系列含环氧基团的丙烯酸酯聚合物（ＨＧＭＢ），并对其改性环氧树脂／４，４‘－二氨基二苯基甲烷的抗冲性能，动态力学行为进行了考察，结果表明：当必性体系中加入质量分数为１５％的ＨＧＭＢ（甲基丙烯酸缩水甘油酯、甲基丙烯酸羟乙基酯、甲基丙烯酸甲酯、丙烯酸丁酯的摩尔分数分别为４．３％、５％、２５．７％、６５％）时，与空白体系相比，改性体系的冲击强度提高５０％，且玻璃化有所提高，模量没有降低。     

Modification Study of Aluminum sec-Butoxide by Acrylic Acid

A new way of modifying aluminum sec-butoxide (Al(OBu^s)₃) is proposed. This synthesis is carried out by reacting Al(OBu^s)₃ dissolved in tetrahydrofuran with an unsaturated acid, viz. acrylic acid.The structure evolution of Al(OBu^s)₃ with increasing acrylic acid amounts is investigated by infrared, ¹H NMR, ¹³ C NMR, and ²⁷Al NMR spectroscopies and viscosity measurements. Information obtained suggests that the exchange reaction occurring between butoxy groups and acrylate ligands is stopped for an acid/alkoxide molar ratio within the range 1.6–1.7. This value leads us to assume that the dominant trimeric species of precursor is preserved after modification. Moreover, ²⁷Al NMR analysis only reveals the presence of hexacoordinated Al sites in the structure of the modified Al(OBu^s)₃.Evidence of the acrylic acid reaction with sec-butanol released during the alkoxide modification is also proved by the infrared and ¹³ C NMR data. However the produced ester amount can be considered as negligible.     

水溶性丙烯酸聚合物的改性及其应用

叙述了水溶性丙烯酸聚合物的改性及其在涂料、胶粘剂、敏感性水凝胶、皮革涂饰剂等方面的应用新进展。     

甲基磺酸对PBO纤维的表面改性

采用甲基磺酸(MSA)溶液对PBO纤维表面进行化学改性,用单丝拔出试验测定了改性前后PBO纤维与环氧树脂基体的界面剪切强度,并通过扫描电镜(SEM)、X-射线光电子能谱(XPS)、接触角分别对处理前后纤维的表面形貌、表面组成以及表面自由能进行了表征.研究结果表明:在甲基磺酸质量分数为60%的溶液中,60℃下处理6 h的PBO纤维与环氧树脂基体的界面剪切强度比未处理的提高了81%,并且纤维表面O元素的质量分数增加了13.3%,表面自由能增加了17.3%.当溶液中甲基磺酸的质量分数、处理时间和处理温度进一步提高时,PBO纤维的皮层将遭受破坏,导致界面剪切强度下降.     

Chalcogen Bonding: An Overview

In the last few decades, “unusual” noncovalent interactions like anion‐π and halogen bonding have emerged as interesting alternatives to the ubiquitous hydrogen bonding in many research areas. This is also true, to a somewhat lesser extent, for chalcogen bonding, the noncovalent interaction involving Lewis acidic chalcogen centers. Herein, we aim to provide an overview on the use of chalcogen bonding in crystal engineering and in solution, with a focus on the recent developments concerning intermolecular chalcogen bonding in solution‐phase applications. In the solid phase, chalcogen bonding has been used for the construction of nano‐sized structures and the self‐assembly of sophisticated self‐complementary arrays. In solution, until very recently applications mostly focused on intramolecular interactions which stabilized the conformation of intermediates or reagents. In the last few years, intermolecular chalcogen bonding has increasingly also been exploited in solution, most notably in anion recognition and transport as well as in organic synthesis and organocatalysis.     

Surface Modification of Banana Fibers by DBD Plasma Treatment

Banana fibers, an environmentally friendly raw material freely available, were physically modified by atmospheric dielectric barrier discharge (DBD) plasma treatment of different dosages. The influence of the plasma treatment applied on the banana fibers was performed considering the mechanical properties, wettability, chemical composition and surface morphology. These properties were evaluated by tensile tests, static and dynamic contact angle, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray diffractometry, conductivity and pH of aqueous extract, differential scanning calorimetry and scanning electron microscopy images. We compare untreated and treated fibers with three different DBD plasma dosages. The results of this study showed considerable modifications in banana fibers when these are submitted to plasma treatment.     

气相生长碳纤维的表面改性及表征

用浓硝酸(65%~68%)对气相生长碳纤维(VGCF)进行了不同时间的表面化学改性。X射线衍射(XRD)分析表明：改性使得VGCF的石墨晶型结构改变，其改变的程度随改性时间的延长而加深；BET比表面积(S_BET)测试表明：改性后的VGCF的S_BET有一定的变化，经120 min长时间的改性处理后，S_BET明显降低；傅立叶变换红外光谱(FTIR)测定得出：改性后VGCF表面上生长了不同类型的含氧基团，其总含量随改性时间的增大而增加；程序升温还原(TPR)得出：改性后VGCF表面上生成有2类以上的热稳定性不同的含氧基团，计算求得含氧基团的氧总含量为2 mmol·g^-1以上；NH₃吸附微量量热测定得出：表面酸性基团的强度和含量随改性时间增加而增大；透射电子显微镜(TEM)结果表明：改性没有明显破坏VGCF的外观结构；吸油值(AOV)实验给出：改性后VGCF的AOV显著降低而亲水性增强；双液法接触角测试给出：改性后VGCF的表面能(SE)明显增大；偶联剂与VGCF作用的FTIR研究表明：改性后VGCF表面含氧基团和偶联剂发生反应，增强了偶联剂在VGCF表面上的结合强度。     

疏水性聚丙烯酸酯人工晶状体的低温等离子体改性

通过低温等离子体表面改性技术对疏水性聚丙烯酸酯人工晶状体进行表面改性, 并对改性前后材料的表面结构、形貌和光学性能进行了表征. 静态水接触角结果显示, 经过氨等离子体处理后的人工晶状体亲水性效果最好, 同时最佳的改性时间为120 s, 改性功率为150 W. XPS分析结果进一步证实, 经等离子体处理后, 在人工晶状体表面引入了极性基团. 原子显微镜观察结果显示, 改性后材料表面更加凹凸不平, 粗糙度显著增加而透光率变化很小, 但过大功率改性的样品透光率明显下降. 时效性测试结果表明, 人工晶状体在改性14 d后疏水性恢复趋于稳定.     

Surface Modification of Textile Fibers and Cords by Plasma Polymerization

In this paper we report on the treatment of industrial fibers and cords by means of plasma polymerization techniques. Coatings of plasma-polymerized pyrrole or acetylene were deposited on aramid fibers, aramid cords and polyester cords. The equipment was a custom-built semi-continuous reactor operated on a pulsed DC glow discharge. The fibers and cords were tested for adhesion to various polymers such as tire cord skim stock rubber compounds and epoxy adhesives. Standard industrial pull-out force adhesion measurement techniques were used. The deposition conditions of the plasma polymer films were varied within wide limits. It was found that, in general, films deposited under low-power and high-pressure conditions performed better than films prepared under high-power and low-pressure conditions. For some systems pulsing of the discharge power improved the performance further. For all systems studied, the optimized plasma polymer surface modification outperformed current industrial standards. The plasma-polymerized coatings were characterized by various techniques and the excellent performance results are explained in a tentative model based on the molecular structure of the films. This structure was found to be strongly dependent on the discharge conditions.     

Microscale Ionic Diodes: An Overview

Ionic rectifier membranes or devices generate uni-directional ion transport to convert an alternating current (AC) ion current input into stored energy or direct current (DC) in the form of ion/salt gradients. Electrochemical experiments 80 years ago were conducted on biological membrane rectifier systems, but today a plethora of artificial ionic rectifier types has been developed and electroanalytical tools are employed to explore mechanisms and performance. This overview focuses on microscale ionic rectifiers with a comparison to nano- and macroscale ionic rectifiers. The potential is surveyed for applications in electrochemical analysis, desalination, energy harvesting, electrochemical synthesis, and in selective ion extraction.     

Total Syntheses of Heliannuols: An Overview

Nature has always been recognized as a rich source for the identification of new drug candidates. Heliannuols have drawn wide attention because of their interesting structural scaffolds and biological potential. Biological evaluation has shown that heliannuols have the allelopathic activity and may be used as lead compounds in herbicides. The synthesis of this family of molecules has always been challenging because of their unique scaffold and multiple chiral centers. Up to now, there have been 32 synthetic routes toward these kinds of natural compounds and a mini-review; however, the synthesis of heliannuols F, I, and J have not been reported yet. Many different strategies such Julia coupling, Dickman condensation, ring-closing metasis, ring contraction or expansion, rearrangement, and intramolecular epoxide opening have been employed in these syntheses. More efficient and highly enantiocontrolled and ecofriendly strategies should be developed for sustainable chemistry.     

Preparation of Monoalkyl Terephthalates: An Overview

Terephthalic acid can be readily converted to the corresponding monoalkyl terephthalate in high yield, via a two‐step procedure. This method is advantageously compared to the more representative methods described in the literature. The purification of the expected monoester, a crucial problem for this synthetic pathway, is discussed, and an original procedure has been developed.