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本文通过研究含氯侧基液晶聚芳醚酮/含甲基苯侧基聚芳醚酮共混体系(结晶/非晶)环带球晶的形态演变和发展过程; 利用选择性溶剂刻蚀方法确定共混体系环带球晶的相组成和相结构, 探讨了环带球晶的形成机理. 相似文献
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液晶聚合物从结构上可分为3种:侧链型、主链型和主侧链型。侧链型液晶聚合物主要是聚丙烯酸酯类、聚硅氧烷类以及磷腈聚合物类。Gray等对聚丙烯酸酯类含不同取代基的联苯结构液晶聚合物进行了研究,结果表明无间隔基且取代基为氰基和饱和脂肪基时,该聚合物呈现近晶型液晶行为。为了增加介晶单元的长径比及刚性,本文在聚甲基丙烯酸酯侧链 相似文献
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以熔融缩聚方法全盛了具有苯烷基侧链取代的全芳香液晶聚酯,用TG,DSC,热台偏光显微镜研究了聚酯的热性能,并讨论了取代基对聚酯热性能的影响,所有合成的聚酯均为热致型液晶,且具有较低的相转变温度。特别是当聚对苯二甲酸对苯二酚酯的两个苯环上分别取代了叔丁基和苯烷基,或取代了两个苯烷基侧链后,聚酯的熔融温度下降到225℃以下,并可在室温下溶于普通的有机溶剂中。 相似文献
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氟硼二吡咯(BODIPY)类pH荧光探针分子是基于光诱导电子转移(PET)的荧光探针分子, 识别基团氮原子上引入不同取代基可呈现不同的光学灵敏度. 本文应用密度泛函理论(DFT)及含时密度泛函理论(TD-DFT)方法对六种含不同取代基的探针分子进行了几何构型优化及激发态计算, 探讨了不同取代基对PET效应影响. 计算结果表明: 基态时这些探针分子的最高占有分子轨道(HOMO)和最低未占有分子轨道(LUMO)都在荧光母体BODIPY的π, π*轨道, 而识别基团上氮原子孤对电子所在的轨道为HOMO-1轨道. 但是在激发态, 当氮原子上有两个取代基时, HOMO-1→LUMO跃迁的激发能都小于荧光团的HOMO→LUMO跃迁, 这将有可能产生PET效应并导致荧光熄灭, 而当氮原子上有一个取代基时不会出现这种现象. 通过激发态结构优化可以发现, 无论识别基团氮原子上有一个还是两个取代基, N原子的轨道对称性都发生变化, 由sp3→sp2, 孤对电子占据在p轨道上, 其轨道能级升高至荧光团的HOMO和LUMO轨道之间, 将导致不同程度的PET效应, 与实验结果一致. 相似文献
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通过5,10,15,20-四(4-羧基苯基)(TCPP)卟啉单体与含螺环结构的二胺单体(SpiroDA)的缩聚反应,实现了含螺环结构的卟啉基固有微孔材料的定向合成(PIM-Spiro)。同时在相同的工艺条件下,以对苯二胺(PPDA),4,4'-二氨基二苯醚(ODA)作为二胺单体分别制备了相应的聚酰胺(PA)网络材料。采用傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、热重分析(TG)、氮气吸附等分析测试手段对3种聚酰胺材料的网络结构和物理化学性能进行了表征。结果表明:螺环扭曲结构的引入可以有效提高微孔卟啉聚合物网络的比表面积,同时在溶剂中表现出很强的溶胀特性;所制备的聚酰胺网络材料中的卟啉基和酰胺键所含的高密度N—H键,赋予材料良好的碱性催化特性。 相似文献
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The interaction between water-soluble sulphonatocalix[4]arene (SC4A) and irinotecan (CPT-11) was investigated by using UV spectrophotometry. Inclusion complex of SC4A with CPT-11 was confirmed by 1H NMR and DSC analysis. Water solubility study showed that SC4A has remarkable solubilisation on CPT-11 and the complex has good water solubility. The antiproliferative activity of the complex was evaluated. The results showed that the complexation of CPT-11 with SC4A increases the antiproliferative activity of CPT-11. 相似文献
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Daisuke Tomida Kiyoshi Kuroda Kentaro Nakamura Kun Qiao Chiaki Yokoyama 《Chemistry Central journal》2018,12(1):127
Using a mass-loss method, we investigated the solubility change of gallium nitride (GaN) in supercritical ammonia with mixed mineralizers [ammonium chloride (NH4Cl)?+?ammonium bromide (NH4Br) and NH4Cl?+?ammonium iodide (NH4I)]. The solubilities were measured over the temperature range 450–550 °C, at 100 MPa. The solubility increased with NH4Cl mole fraction at 450 °C and 100 MPa. The temperature dependence of the solubility curve was then measured at an equal mole ratio of the two mineralizers. The slope of the solubility–temperature relationship in the mixed mineralizer was between those of the individual mineralizers. These results show that the temperature dependence of the solubility of GaN can be controlled by the mineralizer mixture ratio. The results of the van’t Hoff plot suggest that the solubility species were unchanged over the investigated temperature range. Our approach might pave the way to realizing large, high-quality GaN crystals for future gallium-nitride electronic devices, which are increasingly on demand in the information-based age. 相似文献
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Supercriticalfluids(SCFs)havemanyfeaturessuchashighdiffusivity,lowviscosity,andhighcompressibility.Thesemakethemattractivesolventsformanyindustrialprocesses.Supercritical(SC)CO2isthemostpopularamongthem,becauseitisnontoxic,nonflammable,easytoobtain,andhasa… 相似文献
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The aim of this study was to improve the aqueous solubility of highly hydrophobic but selective PDE4 inhibitor N-(3,4-dihydro-2h-1,5-benzodioxepin-7-yl) pyridine-4-carboxamide by associating it with polyamidoamine dendrimer. The PAMAM dendrimer restraining ethylenediamine core synthesized by a divergent approach was utilized for encapsulation. The solubility of conjugates was evaluated on the basis of concentration and generation of the dendrimer, pH of the solution, and temperature. The phase solubility diagram confirmed an increase in aqueous solubility of drug with increase in dendrimer concentration with respect to pH in the order 9.0 > 7.0 > 4.0. Moreover, values of thermodynamic parameters such as negative value of ΔHo, positive value of ΔSo and ΔGo reflects an exothermic complexation, presence of number of particles and spontaneity of the complexation. Overall, investigations validate the enhancement in solubility of drug after complexation with polyamidoamine dendrimer which further confirmed promising bioactivity of the drug-dendrimer conjugates. 相似文献
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Yuhuan Chen Suojiang Zhang Xiaoliang Yuan Yanqiang Zhang Xiangping Zhang Ryohei Mori 《Thermochimica Acta》2006,441(1):42-44
The solubility of CO2 in imidazolium ionic liquids (ILs), 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF4]), 1-hexyl-3-methyl imidazolium tetrafluoroborate ([hmim][BF4]) and 1-octyl-3-methyl imidazolium tetrtafluoroborate ([omim][BF4]) was determined at 305-25 K and pressures from 1 to 9 MPa. The influence of chain length of alkyl substituents on the imidazolium cation on the solubility of CO2 was investigated. The differences in solubility with chain length are in the sequence [omim][BF4] > [hmim][BF4] > [bmim][BF4]. The solubility data were correlated by the extended Henry's law, and enthalpy, Gibbs free energy and entropy changes were obtained. 相似文献
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Jef Peeters Peter Neeskens Marcus Eli Brewster 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):137-139
Pirodavir, 4-[2-[1-(6-Methyl-3-pyridazinyl)-4-piperidinyl]ethoxy]benzoic acid ethyl ester, is an antiviral compound which
has low aqueous solubility (<0.01 mg/ml). The compound is a weak base (pKa 5.8) with high lipophicity (logP 4.44). Ionization
of the compound increases the solubility in acidic medium to 2.3 mg/ml at pH 2.4. However, a low pH is not acceptable for
nasal application as this would induce irritation.
Extensive solubility studies were performed using different types of substituted cyclodextrins in order to select an appropriate
derivate capable of increasing solubility to an acceptable level for formulations for nasal application. Aqueous solubility
of pirodavir increased in a linear fashion with increasing concentration of most of the substituted cyclodextrins. However,
using 2-hydropropyl-β-cyclodextrin (HPBCD) the solubility increased in a non-linear fashion. Based on these studies HPBCD
was selected as the most appropriate excipient.
To support a clinical study on the treatment of rhinovirus cold by intranasal Pirodavir formulations were developed containing
up to 5 mg/ml of pirodavir and up to 10% of HPBCD. Stability of the formulations was studied and found to be acceptable. 相似文献
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采用相溶解度法,通过测定丹皮酚在不同温度不同浓度的β-环糊精(β-CD)、羟丙基-β-环糊精(HP-β-CD)、羟乙基-β-环糊精(HE-β-CD)、取代度为4的磺丁基醚-β-环糊精(SBE4-β-CD)以及取代度为7的磺丁基醚-β-环糊精(SBE7-β-CD)中的溶解度,绘制相溶解度曲线,丹皮酚的溶解度均随5种环糊精浓度的增加而成线性增加,相溶解度曲线为AL型,说明丹皮酚与环糊精以1∶1包合,实验结果表明,5种环糊精对丹皮酚均有增溶作用且SBE7-β-CD的增溶效果最佳. 相似文献
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Modelling of calcium sulphate solubility in concentrated multi-component sulphate solutions 总被引:1,自引:0,他引:1
The chemistry of several calcium sulphate systems was successfully modelled in multi-component acid-containing sulphate solutions using the mixed solvent electrolyte (MSE) model for calculating the mean activity coefficients of the electrolyte species. The modelling involved the fitting of binary mean activity, heat capacity and solubility data, as well as ternary solubility data. The developed model was shown to accurately predict the solubility of calcium sulphate from 25 to 95 °C in simulated zinc sulphate processing solutions containing MgSO4, MnSO4, Fe2(SO4)3, Na2SO4, (NH4)2SO4 and H2SO4. The addition of H2SO4 results in a significant increase in the calcium sulphate solubility compared to that in water. By increasing the acid concentration, gypsum, which is a metastable phase above 40 °C, dehydrates to anhydrite, and the conversion results in a decrease in the solubility of calcium sulphate. In ZnSO4–H2SO4 solutions, it was found that increasing MgSO4, Na2SO4, Fe2(SO4)3 and (NH4)2SO4 concentrations do not have a pronounced effect on the solubility of calcium sulphate. From a practical perspective, the model is valuable tool for assessing calcium sulphate solubilities over abroad temperature range and for dilute to concentrated multi-component solutions. 相似文献