梳状高分子烷基侧链构象和堆积结构的红外光谱研究

以正十九烷和两种接枝烷基链的梳状高分子N-十八烷基聚乙烯亚胺(PEI18C)、N-十八烷基聚对苯甲酰胺(PBA18C)为研究对象,利用红外光谱对处于受限和自由状态的烷基链的构象和堆积结构随温度的变化进行了对比研究.结果表明,处于受限和自由状态的烷基链的构象排列和堆积结构及其转变行为不同,且受限于柔性PEI主链和刚性PBA主链的烷基链也不相同.从主链刚性的角度,探讨了影响烷基侧链构象和堆积结构的原因.     

二烷基二茂铁甲酰化反应的研究

甲酰基二茂铁是一种极为重要的二茂铁衍生物。以它为中间体 ,经缩合、还原和氧化等反应 [1～ 3] ,可得到许多其它的二茂铁化合物。在甲酰基二茂铁分子中引入烷基后 ,其性质在两个方面会发生显著变化。一是含碳量增加 ,导致其衍生物在有机溶剂中的溶解度增加 ;另一是化合物的物态发生了很大变化 ,固态会变为液态 ,高熔点物会变为低熔点物 ,为合成液态或低熔点二茂铁化合物提供了丰富的中间体。有关二烷基二茂铁甲酰化反应的报道甚少[4 ] ,更未见系统地研究过多种不同烷基的引入对甲酰化反应的影响。为此我们研究了 6种二烷基二茂铁的 Vilsme…     

有机锆交联羧烷基羟烷基纤维素的热性质

兼含离子型取代基(羧烷基钠盐)和非离子型取代基(羟烷基)的羧烷基羟烷基纤维素(CAHAC)复醚,由于其结构特点和性能优点,已愈来愈广泛地为人们所重视^[1-3]。有关其有机交联改性或无机交联改性的研究结果表明,在耐热增稠剂、耐盐吸水材料^[4]、尤其是在油田开采化学方面,CAHAC都有很大的发展前途。     

合成磷酰氯二烷基酯的新方法

以亚磷酸三烷基酯为原料,三氯异氰尿酸为氯代试剂,二氯甲烷为溶剂,在室温下合成了磷酰氯二烷基酯,其结构经1H NMR, 31P NMR和GC-MS确证.     

二烷基磷酸的结构与萃取稀土性能的研究

由于二(2-乙基己基)磷酸(P204)对稀土的萃取能力过强,对重稀土反萃取较困难,而改变二烷基磷酸类萃取剂的烷基结构有可能改善它对重稀土的反萃取性能。本研究考察了二(β-丁基辛基)磷酸(DDPA),二(β-己基癸基)磷酸(DHDPA-1),二(10-乙基十四烷基-7)磷酸(DHDPA-2)和二[β-(1,3,3-三甲基丁基),5,7,7-三甲基辛基]磷酸(DODPA)四种具有长碳链结构的萃取剂对稀土的萃取和反萃取性能,并与二(2-乙     

胺烷基二茂铁衍生物的合成及其结构与性质的研究

选择不同的胺组分，利用改进的Ugi法合成了一系列含有胺烷基的二茂铁衍生物，并对其结构和性质进行了研究。     

由烷基吡啶和喹啉同系物的保留指数推算结构参数的探讨

随着人们对化合物的色谱保留及其物化性质、结构参数间关系的研究,为色谱法推测化合物的物化性质及分子结构提供了可能性。我们曾把烷基喹啉、苯氧烷基吡啶类等同系列化合物的保留指数(I_R)与其分子量(M),分子中碳原子数(N),分子连通性指数(X)等作了关联,得到了I_R与M、N间的近似线性关系和I_R与X间的良好线性关系。本文根据该关系对15种烷基吡啶和6种烷基喹啉化合物的M、N和X进行计算,获得了较好的结果。     

内型异莰烷基甲醛肟及其烷基醚的合成 与抑菌活性

以内型异莰烷基甲醛与盐酸羟胺反应合成了内型异莰烷基甲醛肟,继而与卤代烃反应又得到5种内型异莰烷基甲醛肟烷基醚衍生物。所有6种化合物的结构通过GC-MS、~1HNMR、~(13)CNMR和IR分析方法进行表征。采用菌丝生长速率法,测试了6种化合物对12种植物病原真菌的抑菌活性。结果表明:所有的内型异莰烷基甲醛肟对12种植物病原真菌的生长有很好的抑制作用,所有内型异莰烷基甲醛肟烷基醚类化合物对6种植物病原真菌的生长也具有一定的抑制作用。     

1-烷基-1''-乙酰基二茂铁的合成

用新方法合成了1-烷基-1'-乙酰基二茂铁,该法与传统方法相比易于得到单一产物.通过7种1-烷基二茂铁甲酸与三氯化磷作用形成酰氯,再与乙酰乙酸乙酯的钠盐进行反应,皂化脱羧得到1-烷基-1'-乙酰基二茂铁化合物,用元素分析、红外光谱、核磁共振氢谱确定了化合物的结构.     

全氟烷基磺酸盐和全氟烷基磺酰亚胺盐的多相化催化研究

传统的Lewis酸催化剂在环境的压力下受到挑战,全氟烷基磺酸盐和全氟烷基磺酰亚胺盐作为均相、高效的Lewis酸催化剂在有机合成中受到人们的关注.为了简化分离操作,人们对全氟烷基磺酸盐和全氟烷基磺酰亚胺盐的多相化进行了研究,并已取得巨大进展.本文综述了全氟烷基磺酸盐和全氟烷基磺酰亚胺盐分别负载在有机载体、无机载体以及离子液体上的多相化催化最新研究进展,简要概括了其制备方法和催化活性,并对其催化应用前景进行了展望.     

The hydrolytic stability of some cyclourea compounds

The hydrolytic behavior of some cyclourea compounds was studied in a Calvet microcalorimeter and a hydrolytic testing apparatus. Information was obtained on their hydrolytic stabilities.     

硅氮化合物的结构与水解稳定性的关系

采用硅氮化合物本体与水蒸汽直接作用的方法,研究了一系列硅氮化合物的结构与水解稳定性之间的关系.结果表明,空间位阻越大则硅氮化合物水解稳定性越好,环张力对硅氮烷的水解稳定性有一定的影响,但空间位阻的作用更为显著.带有苯基的环二硅氮烷、六苯基环三硅氮烷和含硅氮键的高分子聚合物具有较大的空间位阻,因此水解稳定性非常好.     

气相色谱-氮磷检测器法表征家蝇对马拉硫磷的水解代谢

为明确家蝇对马拉硫磷的水解代谢能力及相关代谢抗性，在用常规模式底物α-萘乙酯表征了敏感及抗性家蝇的水解酶活性的基础上，使用气相色谱-氮磷检测器（GC-NPD）法比较了抗性及敏感家蝇水解酶对马拉硫磷的水解代谢能力的差异。结果表明，用2：1（v/v）的乙酸乙酯与正己烷混合物萃取后，GC-NPD可成功测定家蝇酶制备液与马拉硫磷温育后的马拉硫磷含量变化，从而可以表征家蝇酶制备液对马拉硫磷的代谢能力。马拉硫磷抗性家蝇水解酶代谢α-萘乙酯的能力是敏感家蝇的1.39倍，代谢马拉硫磷的能力是敏感家蝇的6.68倍，表明家蝇对马拉硫磷的抗性与其对马拉硫磷代谢能力增强有关。该法可用于家蝇等昆虫对马拉硫磷的代谢能力及相关抗性机制研究。     

Greatly enhanced hydrolytic degradation ability of poly(L-lactide) achieved by adding poly(ethylene glycol)

Plasticized poly(L-lactide)(PLLA) materials have been applied in many fields and the microstructure performance of such materials attracts much attention of researchers. However, few reports declared the hydrolytic degradation ability of the plasticized PLLA materials. In this article, a small quantity of poly(ethylene glycol)(PEG) was introduced into PLLA, which aimed to understand the hydrolytic degradation behavior of the plasticized PLLA materials. The microstructures of the plasticized samples were comparatively investigated using scanning electron microscopy(SEM), wide angle X-ray diffraction(WAXD), differential scanning calorimetry(DSC) and Flourier transform infrared spectroscopy(FTIR), etc. The results demonstrated that PEG improved the hydrophilicity of sample surface, and the relatively high content of PEG enhanced the crystallization ability of PLLA matrix. The hydrolytic degradation measurement was carried out at 60 ℃ in an alkaline solution of pH = 12. The results demonstrated that the plasticized PLLA samples exhibited accelerated hydrolytic degradation compared with the pure PLLA sample, and the hydrolytic degradation was also dependent on the PEG content. Further results demonstrated that PEG induced the change of hydrolytic degradation mechanism possibly due to the good dissolution ability of PEG in water, which provided more paths for the penetration of water. Furthermore, the microstructure evolution of the plasticized PLLA during the hydrolytic degradation process was also investigated, and the results demonstrated the occurrence of PLLA crystallization, which was possibly contributed to the decreased hydrolytic degradation rate observed at relatively long hydrolytic degradation time. This work is of great significance and may open a new way for promoting the reclamation of PLLA waste material.     

Graphene oxide induced hydrolytic degradation behavior changes of poly(l-lactide) in different mediums

Graphene oxide (GO) has been widely used in polymer-based composites due to their promising properties originated from the two-dimensional platelet-like structure and a large number of oxygen-containing groups, including reinforcement effect, nucleation effect, barrier effect, etc. In this work, GO was introduced into poly(l-lactide) (PLLA) and the main attention was focused on investigating the effect of GO on hydrolytic degradation behavior of PLLA. The hydrolytic degradation measurements were carried out in three different mediums, including alkaline solution with a pH value of 12, acidic solution with the pH value of 2 and deionized water with the pH value of 7. It was demonstrated that in all mediums, the hydrolytic degradation of PLLA was greatly accelerated by adding GO and specifically, the more the GO in the composites, the more apparent the acceleration effect of the hydrolytic degradation was, furthermore, GO didn't change the hydrolytic degradation mechanisms of the PLLA matrix in all mediums. The microstructure evolution of the PLLA matrix during the hydrolytic degradation process was also comparatively investigated. The results demonstrated that crystallization occurred during the hydrolytic degradation process and the crystallization of the composites was also greatly promoted by GO. This work provides valuable information for the application and reclamation of the PLLA/GO composites.     

主链含环二硅氮烷硅橡胶水解稳定性的研究

<正> 一般说,硅氮键对水不稳定,因此聚硅氨烷尽管具有较好的耐热性,但是仍未得到应用。等指出,硅原子或氮原子上带有较大的空间位阻的基团后,如苯基等,可以提高硅氨烷的水解稳定性,取代基的电子效应对其水解稳定性也有影响。Fink发现     

Effects of thermoresponsive coacervation on the hydrolytic degradation of amphipathic poly(gamma-glutamate)s

Hydrolytic properties of thermoresponsive biopolymers with amphiphilic structures, gamma-PGA-P, were investigated. Hydrolysis was monitored in terms of molecular weight changes using GPC and spectroscopic measurements. The hydrolytic degradation of gamma-PGA-P was controlled by a change in the degree of propyl group conversion, reaction temperature, and/or reaction pH. The degradation was classified as the rapid elimination of propyl side chains and the moderate cleavage of peptide linkages in the backbone. Furthermore, hydrophobic environments established by the thermoresponsive coacervation of gamma-PGA-P60 solutions inhibited hydrolytic degradation reactions. Inversely, hydrolytic degradations increased coacervation temperatures. Kinetic studies of hydrolytic reactions suggest that the degradation rate of gamma-PGA-P60 solutions can be controlled by their thermoresponsivity. The hydrolysis reported here represents the first degradation rate controlled by thermoresponsive coacervation.     

Poly(methyl methacrylate)-induced Microstructure and Hydrolysis Behavior Changes of Poly(L-lactic acid)/Carbon Nanotubes Composites

Poly(L-lactic acid)(PLLA)-based composites exhibit wide applications in many fields.However,most of hydrophilic fillers usually accelerate the hydrolytic degradation of PLLA,which is unfavorable for the prolonging of the service life of the articles.In this work,a small quantity of poly(methyl methacrylate)(PMMA)(2 wt%-10 wt%)was incorporated into the PLLA/carbon nanotubes(CNTs)composites.The effects of PMMA content on the dispersion of CNTs as well as the microstructure and hydrolytic degradation behaviors of the composites were systematically investigated.The results showed that PMMA promoted the dispersion of CNTs in the composites.Amorphous PLLA was obtained in all the composites.Largely enhanced hydrolytic degradation resistance was achieved by incorporating PMMA,especially at relatively high PMMA content.Incorporating 10 wt%PMMA led to a dramatic decrease in the hydrolytic degradation rate from 0.19%/h of the PLLA/CNT composite sample to 0.059%/h of the PLLA/PMMA-10/CNT composite sample.The microstructure evolution of the composites was also detected,and the results showed that no crystallization occurred in the PLLA matrix.Further results based on the interfacial tension calculation showed that the enhanced hydrolytic degradation resistance of the PLLA matrix was mainly attributed to the relatively strong interfacial affinity between PMMA and CNTs,which prevented the occurrence of hydrolytic degradation at the interface between PLLA and CNTs.This work provides an alternative method for tailoring the hydrolytic degradation ability of the PLLA-based composites.     

Hydrolytic degradation behavior of poly(l-lactide)/SiO2 composites

In this work, different contents of nano-silica (SiO₂) particles were introduced into poly(l-lactide) (PLLA) to prepare PLLA/SiO₂ composites though a two-step compounding method, i.e. solution compounding (preparing master batch) and subsequent melt compounding (master batch dilution). The dispersion of SiO₂ was characterized using scanning electron microscope (SEM). The hydrophilicity of the material was evaluated by measuring the contact angle of water on the sample surface. The hydrolytic degradation measurements of the nanocomposites were carried out in alkaline solution at two different temperatures, i.e. 37 and 55 °C. Subsequently, microstructure evolution of PLLA matrix during the hydrolytic degradation process was systematically investigated using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The results showed that SiO₂ had good dispersion in the PLLA matrix. Largely enhanced hydrolytic degradation ability was achieved for PLLA/SiO₂ composites. Increasing the content of SiO₂ or enhancing the hydrolytic degradation temperature accelerated the hydrolytic degradation of PLLA matrix. Further results showed that SiO₂ promoted the reorganization of microstructure of PLLLA matrix during the hydrolytic degradation process.     

Role of hydrolytic degradation of polylactide drug carriers in developing micro- and nanoscale polylactide-based drug dosage forms

The present analytical survey explores different aspects of hydrolytic degradation of drug dosage forms (DF) based on polylactides, homopolymers of lactic acid (PLA) and copolymers of lactic and glycolic acids (PLGA). The study includes various scientific data from multiple sources describing the effect of the PLGA nanocarrier hydrolytic degradation rate on the profile of drug release from the DFs intended for intravenous and intramuscular administration, including micro- and nanoparticles, and implants. The following aspects are explored in the review: design of experiments aimed at studying the hydrolytic degradation kinetics of PLGA carriers; commonly employed analytical methods; interpretation of the mechanism of PLGA-based DF hydrolytic degradation; factors that influence the hydrolytic degradation rate of PLGA drug carriers as part of DFs; interrelation between the processes of polymer carrier hydrolytic degradation and drug substance release from the PLGA-based DFs.