超临界CO2在高分子合成与制备中的应用

介绍超临界二氧化碳流体作为介质在高分子合成与制备中的研究进展。文中表明，可在超临界二氧化碳中实施氟代单体的自由基溶液聚合、甲基丙烯酸甲酯的分散聚合、丙烯酸的沉淀聚合、丙烯酰胺的反相乳液聚合以及异丁基乙烯基醚的阳离子聚合等多种聚合反应，可用超临界二氧化碳溶胀聚合法制备梯度共混物。此外，超临界二氧化碳还可用于聚合物分级和聚合物微孔、微纤与微球材料的制备等，显示出超临界二氧化碳是一种对环境无污染且价廉的     

超临界二氧化碳中聚合体系的发展与新型功能高分子材料的制备

因拥有诸多特性,超临界二氧化碳作为聚合反应介质受到了学术界和工业界的广泛关注。近十余年来,超临界二氧化碳中聚合体系的研究有了新的进展,反应介质由单一二氧化碳发展为二氧化碳/水或二氧化碳/有机溶剂复合物,得益于连续搅拌反应装置的出现,聚合方式由间歇式发展为连续式。同时,在超临界二氧化碳中制备得到了多种新型功能高分子材料,例如含氟塑料、含氟弹性体、核壳复合材料、多孔材料以及膜材料,显示出传统溶剂无法比拟的优越性。本文对以上两方面作一介绍和评述。     

New Polymerization Systems in Supercriticai Carbon Dioxide and Related Functional Polymer Materials

因拥有诸多特性,超临界二氧化碳作为聚合反应介质受到了学术界和工业界的广泛关注。近十余年来,超临界二氧化碳中聚合体系的研究有了新的进展,反应介质由单一二氧化碳发展为二氧化碳／水或二氧化碳／有机溶剂复合物,得益于连续搅拌反应装置的出现,聚合方式由间歇式发展为连续式。同时,在超临界二氧化碳中制备得到了多种新型功能高分子材料,例如含氟塑料、含氟弹性体、核壳复合材料、多孔材料以及膜材料,显示出传统溶剂无法比拟的优越性。本文对以上两方面作一介绍和评述。     

超临界二氧化碳-高分子化学中的绿色介质

介绍了超临界二氧化碳的特点，综述了近期以超临界二氧化碳为溶剂的高分子聚合和高分子化学反应及其应用前景。指出超临界CO2在聚合反应中能作为传统有机溶剂的替代溶剂。     

超临界CO2中的高分子合成研究进展

本文介绍以超临界CO₂流体为介质的高分子合成的研究进展。说明可在超临界二氧化碳中实施氟代单体的自由基溶液聚合、甲基丙烯酸甲酯和苯乙烯的分散聚合、丙烯酸的沉淀聚合、丙烯酰胺的反相乳液聚合以及异丁基乙烯基醚的阳离子聚合等多种聚合反应。这显示出超临界CO₂是一种对环境无污染且价廉的替代溶剂。     

超临界二氧化碳中过渡金属催化有机反应研究进展

主要综述了近年来超临界二氧化碳作为反应介质过渡金属催化有机反应的最新进展.通过与常规有机溶剂中有机反应的对比,着重介绍了超临界二氧化碳作为反应介质在有机反应中所显示出的优越性,例如调控反应的选择性,提高反应速度和增加催化剂催化效率等.     

超临界(压缩)二氧化碳介质中的选择氧化*

由于超临界二氧化碳（SCCO₂）具有稳定、安全、不燃、清洁无毒、粘度小、扩散快、可压缩的特殊性质,所以使得超临界二氧化碳非常适合作为催化反应的绿色溶剂.除此之外,多种气体在超临界二氧化碳中的溶解度很高,这对于那些受传质阻碍和易引起安全隐患的气相反应来讲,使用SCCO₂作为替代的反应溶剂具有重要的价值。值得指出的是：如果选择超临界二氧化碳作为氧化反应的溶剂,其自身不会发生反应而产生副产物,从而容易得到清洁的产物。本文主要讨论了超临界二氧化碳作为反应介质对醇、烯烃和烷烃等选择氧化反应的影响,通过与传统溶剂比较可以看出超临界二氧化碳作为氧化反应溶剂的优势,对近几年来以分子氧为氧化剂,以超临界二氧化碳为介质的催化选择氧化的反应体系作了综述,并对未来的发展提出了展望。     

超临界二氧化碳中羰基钴催化的端基炔烃环三聚反应研究

原子经济性良好的炔烃[2+2+2]环加成反应与绿色溶剂超临界二氧化碳相结合,是一个符合绿色化学原则的环境友好反应过程.建立了一个纯超临界二氧化碳介质中八羰基二钴催化的端基炔烃环三聚反应体系,在优化的反应条件下,以较高产率选择性地制备1,2,4-三取代苯衍生物.优化了催化剂用量、二氧化碳压力、反应温度及时间等反应条件,讨论了反应物料及催化剂在超临界二氧化碳介质中的溶解性和相行为,提出了端基炔烃环三聚反应机理,并将反应底物从C≡C键拓展至C≡N键,对超临界二氧化碳介质中炔-腈环加成反应进行了初步探索.优化出的炔烃环三聚催化反应体系无需使用有机助溶剂和各类助剂,底物适应性好,产物选择性高,为合成1,2,4-三取代苯衍生物提供了一种绿色合成方法.     

超临界二氧化碳中的高分子合成

近年来,超临界二氧化碳（sc-CO2）在聚合反应中的应用受到了越来越多的关注。本文主要综述了以sc-CO2为反应介质的自由基聚合、阳离子聚合、过渡金属催化聚合、热致开环聚合、溶胶-凝胶聚合以及氧化耦合聚合的研究概况。一系列研究结果表明sc-CO2是非常有前途的反应溶剂,在高分子合成领域将会有更加广阔的应用前景。     

过渡金属催化的烯烃羰基化反应现状与进展

阐述了烯烃羰基化反应在区域选择性和立体选择性方面的现状与最新进展,同时对羰基化反应新进展－超临界二氧化碳流体作为反应介质也作了综述。     

用微扰硬球链理论计算超临界CO-2-溶质二元系的密度

溶质在超临界流体中的溶解度与流体的密度密切相关。本文采用微扰硬球链理论对纯CO2及CO2-正戊烷、CO2-正庚烷、CO2-正癸烷体系在不同条件下的密度进行计算,计算值与文献给出的实验值符合很好。     

Diterpenoid Compounds Isolated from Chloranthus oldhamii Solms Exert Anti-Inflammatory Effects by Inhibiting the IKK/NF-κB Pathway

Chloranthus oldhamii Solms (CO) is a folk medicine for treating infection and arthritis pain but its pharmacological activity and bioactive compounds remain mostly uncharacterized. In this study, the anti-inflammatory compounds of C. oldhamii were identified using an LPS-stimulated, NF-κB-responsive RAW 264.7 macrophage reporter line. Three diterpenoid compounds, 3α-hydroxy-ent-abieta-8,11,13-triene (CO-9), 3α, 7β-dihydroxy-ent-abieta-8,11,13-triene (CO-10), and decandrin B (CO-15) were found to inhibit NF-κB activity at nontoxic concentrations. Moreover, CO-9 and CO-10 suppressed the expression of IL-6 and TNF-α in LPS-stimulated RAW 264.7 cells. The inhibitory effect of CO-9 on TNF-α and IL-6 expression was further demonstrated using LPS-treated bone marrow-derived macrophages. Furthermore, CO-9, CO-10, and CO-15 suppressed LPS-triggered COX-2 expression and downstream PGE2 production in RAW 264.7 cells. CO-9 and CO-10 also reduced LPS-triggered iNOS expression and nitrogen oxide production in RAW 264.7 cells. The anti-inflammatory mechanism of the most effective compound, CO-9, was further investigated. CO-9 attenuated LPS-induced NF-κB activation by reducing the phosphorylation of IKKα/β (Ser176/180), IκBα (Ser32), and p65 (Ser534). Conversely, CO-9 did not affect the LPS-induced activation of MAPK signaling pathways. In summary, this study revealed new anti-inflammatory diterpenoid compounds from C. oldhamii and demonstrated that the IKK-mediated NK-κB pathway is the major target of these compounds.     

无机氧化物复合纳米材料的制备、表征及其对蓝色染料光催化降解的探讨

采用化学共沉淀法合成Fe0.6Cr0.4/Bi7MnO12.5复合纳米材料，用透射电子显微镜（TEM）、X射线粉末衍射分析（XRD）、红外光谱（FTIR）等手段对材料进行表征，用Na2CO3溶液浸渍复合纳米晶作为催化剂，对蓝色染料进行光催化降解探讨。     

Partitioning of quencher ions in the micellar microenvironment of polyoxyethylene nonyl phenol

This paper has explored the quenching of fluorescence of the dye safranine T (ST) by the inorganic cations viz Cu2+, Co2+, Ni2+ and Mn2+ in micellar solutions of the surfactant dioxyethylene nonyl phenol (Igepal CO-210), pentaoxyethylene nonyl phenol (Igepal CO-520) and dodecaoxyethylene nonyl phenol (Igepal CO-720). The quenching results have been calculated in light of stern volmer equation (SV) to evaluate the extent of interaction between the fluorophore (ST) and quencher. The average concentration of the quencher ions in the micelle have been determined. The quenching efficiency of ST by inorganic ions in micellar medium is lower than that in aqueous medium. The results show that the ions get partitioned in the micellar medium. The values of the partition coefficient of the ions decrease with increase in HLB value and number of oxyethylene groups in Igepal.     

Supramolecular assemblies of organogelators featuring benzimidazole and long-chain pyridine dicarboxyamide

Two organogelators, CO-01 and CO-03 , featuring benzimidazole and long-chain pyridine carboxyamide groups were prepared and their physical properties were fully explored. CO-01 and CO-03 are capable of transforming various organic solvents to organogels. The morphologic investigations of these organogels have shown that the supramolecular assemblies, in the forms of fibers and spheres, are readily generated from the aggregates of CO-01 and CO-03 . The sol–gel interconversion can be readily achieved by tuning the gelator concentration and temperature. By manipulating the redox state of anthraquinone group in CO-03 , the gel–sol transition for the organogels of CO-03 can be reversibly tuned by either chemical or electrochemical oxidation/reduction reactions. The presence of polarized imidazole and amide N–H groups allows anion-induced gel collapse. The accompanying colorimetric and ratiometric fluorescent responses of gels CO-01 and CO-03 to F⁻ and CN⁻ render these organogelators being sensitive and selective anion probes.     

ABO_2型复合氧化物上CO-NO的反应性能

以柠檬酸络合法制备了 CuCrO_2、 CuAlO_2和 CuFeO2等具有铜铁矿结构的 ABO2型复合氧化物,并考察了它们在氧化和还原气氛中对 CO- NO反应的影响 . CuAlO_2和 CuCrO_2具有好的催化活性, CuCrO_2更具有相当的稳定性,经过氧化和还原条件下的 CO- NO反应后,体相组成仍然保持不变 . CuAlO_2在还原条件下,部分被还原生成了零价铜 . CuFeO_2的催化活性和稳定性较差,在还原气氛中催化 CO- NO反应过程中,样品被还原,完全转化成了 Cu0和 CuFe2O4.     

棕榈酸修饰的α-螺旋两亲性多肽的共组装

设计合成了3条棕榈酸修饰的两亲性多肽C₁₅H₃₁CO-(AEELAKK)₃-NH₂(PA1), C₁₅H₃₁CO-(AEALAKK)₃-NH₂(PA2) 和C₁₅H₃₁CO-(AEELAKA)₃-NH₂(PA3), 研究了其在水溶液中的自组装行为以及带净正电荷的PA2 和带净负电荷的PA3 等比例混合后的共组装行为, 并推测了其机理. 圆二色谱分析结果表明, 其二级结构均为α-螺旋结构, PA2和PA3等比例混合后α-螺旋含量升高. 利用透射电镜观察了PA1, PA2, PA3以及PA2+PA3(体积比1: 1)自组装体的形貌, 结果表明, PA2和PA3等比例混合后共组装形成了长的纳米纤维. 芘荧光探针研究了3种两亲性多肽以及PA2+PA3 的临界胶束浓度.     

聚丙烯与马来酸酐在超临界CO2中的接枝聚合

聚丙烯(PP)以其强度高、耐热性好、密度小、易加工和价廉等特点成为重要的通用塑料。但由于非极性的分子结构,其亲水性、染色性、抗静电性、粘接性和印刷性并不理想,难以与极性聚合物和填料共混、复合。PP通过接枝引入极性基团是最常用的化学改性方法。常用的接枝单体有马来     

Theoretical study of the CH2 + O photodissociation of formaldehyde adsorbed on the Ag(111) surface

Configuration interaction calculations of the ground and excited states of the H2CO molecule adsorbed on the Ag(111) surface have been carried out to study the photoinduced dissociation process leading to polymerization of formaldehyde. The metal-adsorbate system has been described by the embedded cluster and multireference configuration interaction methods. The pi electron-attachment H2CO- and n-pi* internally excited H2CO* states have been considered as possible intermediates. The calculations have shown that H2CO* is only very weakly bound on Ag(111), and thus that the dissociation of adsorbed formaldehyde due to internal excitation is unlikely. By contrast, the H2CO- anion is strongly bound to Ag(111) and gains additional vibrational energy along the C-O stretch coordinate via Franck-Condon excitation from the neutral molecule. Computed energy variations of adsorbed H2CO and H2CO- at different key geometries along the pathway for C-O bond cleavage make evident, however, that complete dissociation is very difficult to attain on the potential energy surface of either of these states. Instead, reneutralization of the vibrationally excited anion by electron transfer back to the substrate is the most promising means of breaking the C-O bond, with subsequent formation of the coadsorbed O and CH2 fragments. Furthermore, it has been demonstrated that the most stable state for both dissociation fragments on Ag(111) is a closed-shell singlet, with binding energies relative to the gas-phase products of approximately 3.2 and approximately 1.3 eV for O and CH2, respectively. Further details of the reaction mechanism for the photoinduced C-O bond cleavage of H2CO on the Ag(111) surface are also given.     

New types of nonclassical iridium carbonyls formed in Ir-ZSM-5: a Fourier transform infrared spectroscopy investigation

In this work we report some new nonclassical carbonyls of iridium formed after CO adsorption on Ir-ZSM-5 (Ir-MFI). Mainly Ir+ cations were found on sample activated at 523 K and reduced by CO at the same temperature. With CO they formed Ir+(CO)2 gem-dicarbonyls (2104 and 2033 cm(-1)) that decomposed at 673 K without leaving a measurable fraction of monocarbonyls. The dicarbonyl structure was established by 12CO-13CO coadsortpion experiments. In the presence of CO in the gaseous phase and at ambient temperature the Ir+(CO)2 dicarbonyls were converted into Ir+(CO)3 species (2182, 2099, and 2074 cm(-1)). At 100 K these complexes are able to accommodate a fourth CO molecule thus producing tetracarbonyls (2155, 2145, 2125, and 2105 cm(-1)). The results are explained by the high coordinative unsaturation of the Ir+ cations in the ZSM-5 matrix. This is also the reason for the formation of mixed Ir+(H2O)(CO)2 species after CO-H2O coadsorption (2087 and 2015 cm(-1)). Evacuation of the sample at 673 K, followed by treatment with CO at 523 K, generates Ir2+ cations. With CO these cations form another kind of geminal complex, namely, Ir2+(CO)2 species (2173 and 2129 cm(-1)). Here again, the structure was confirmed by 12CO-13CO coadsortpion experiments. These dicarbonyls are decomposed at 573 K (again without producing monocarbonyls) and are able to accommodate additionally neither CO nor water molecules. The results are explained by the smaller cationic radius of Ir2+ (as compared to Ir+), which is associated with a decrease of the number of ligands required for coordinative saturation.