含酯键和烷氧基胺的两亲性嵌段聚合物胶束的制备及聚焦超声响应行为

以聚乙二醇单甲醚(m PEG)为亲水段,聚丙二醇单丁醚(PPG)为疏水段,用酯键(COO)和烷氧基胺(CON)将它们连接在一起制得了两亲性嵌段聚合物PEG-COO-CON-HDI-PPG。采用核磁共振氢谱对产物的结构进行了表征。通过选择性溶剂诱导法制备了嵌段聚合物胶束,研究了聚合物胶束在高强度聚焦超声(HIFU)下的响应行为。结果表明,超声可使烷氧基胺均裂和酯键水解;用该胶束包覆药物,可以实现对药物的超声控制释放。     

纤维素及其酯接枝聚乙二醇制备相变储能材料的研究

采用溶液接枝聚合法,在异氰酸酯存在下,将聚乙二醇(PEG)分别链接到纤维素(Cell-OH)、纤维素醋酸酯(CDA)及纤维素月桂酸酯(LACE)骨架高分子材料上,制备了Cell-OH/PEG、CDA/PEG和LACE/PEG3种固-固相变储能材料,并通过FT-IR、TEM、POM、XRD和DSC等分析手段,对3种产物结构、结晶特性及相变储能性能等进行了比较研究。结果表明,随着与PEG接枝聚合的纤维素酯链的增长,所得产物形成酯链包裹PEG的胶囊的趋势越强,对PEG结晶的破坏程度越小,从而使产物的相变焓越高。     

NMR研究聚乙二醇的热氧降解

采用1H，13C和2D－NMR技术研究了聚乙二醇（PEG）的热氧降解，对产物的结构作了详细分析和表征，并定量讨论了抗氧剂2，6－二叔丁基－4－甲基酚（BHT）对其热氧解降解的影响，PEG的氧化降解发生在醚键氧碳上，遵循自由基氧化机理，最后形成大量的甲酸酯等酯类以及甲基，亚甲二氧基和醇，抗氧剂BHT不仅降低了PEG的氧化降解程度，而且改变了降解产物的结构分布，显著抑制了碳酸酯和亚甲二氧基结构的生成，相对增加了端羟基和端甲基结构。     

对氨基苯甲酸壳聚糖酯的制备、表征及抗菌活性

壳聚糖(CTS)经氨基保护合成席夫碱,再与由对氨基苯甲酸和氯化亚砜制备的对氨基苯甲酰氯反应,产物在一定pH下氨基去保护得到了对氨基苯甲酸壳聚糖酯(ABCTSE)。产物经FT-IR、1H NMR、13C NMR进行结构表征,证实为目标产物;由元素分析得到所制得壳聚糖酯的酯化度为16.8%、40.4%;室温下,壳聚糖衍生物在蒸馏水及有机试剂中的溶解性比壳聚糖更好;产物的TG和DTG分析结果表明所制得壳聚糖酯的稳定性稍低于壳聚糖。另外,由于分子结构中两个氨基的存在,其溶于弱酸性溶液后随着形成—NH3+的增多,使其在抑菌方面有更大优势。     

含铍聚碳硅烷的合成机理研究

含铍SiC陶瓷纤维是一种新型的高性能SiC纤维,而优质含铍聚碳硅烷先驱体(PBCS)的合成是得到该种纤维的重要保证。以乙酰丙酮铍(Be(acac)_2)和聚碳硅烷(PCS)为原料制备得到PBCS,并对其合成机理进行了深入研究,采用PCS和石蜡分别与Be(acac)2进行对比反应,用GC-MS对反应小分子产物进行分析,确定了Be(acac)_2与PCS的成键反应实际是Be与Si—H键反应,C—H键没有参与含铍键的形成反应;根据小分子反应产物的生成途径,合理分析了PBCS的合成反应原理。     

4-羟基苯甲酸-2′-辛酯的合成

以对羟基苯甲酸为起始原料 ,经羟基保护、酯化和脱羟基保护三步反应 ,合成了难以用传统酯化法制备的 4 羟基苯甲酸 2′ 辛酯 ,总收率 6 5 % ,产物结构经IR及MS鉴定。     

4-羟基苯甲酸-2'-辛酯的合成

以对羟基苯甲酸为起始原料,经羟基保护、酯化和脱羟基保护三步反应,合成了难以用传统酯化法制备的4-羟基苯甲酸-2'-辛酯,总收率65%,产物结构经IR及MS鉴定.     

PEG基复合固体电解质与Al的阳极键合性能研究

为了探究PEG基固体电解质与金属的阳极键合性能,本文以聚乙二醇(PEG)为基体,引入LiClO4提供导电粒子,并采用纳米颗粒(CeO2、SiO2)对其络合物进行改性,制备了PEG基复合固体电解质(PEG)10LiClO4-SiO2和(PEG)10LiClO4-CeO2,研究了其与铝的阳极键合性能.通过交流阻抗、X射线衍射、SEM扫描电镜、力学实验及阳极键合实验等对所制备样品进行分析和表征.研究发现,经过碱金属锂盐及无机纳米颗粒改性后,破坏了PEG材料原有的分子结构,有效抑制了材料内部结晶,促进了离子迁移,提高了基体的室温电导率及力学性能.本文所制备的PEG基复合固体电解质与铝成功实现了阳极键合连接,(PEG) 10 LiClO4-8wt.％ CeO2与Al的阳极键合性能最佳,在结合界面处所生成的键合层是其连接的关键因素.     

双金属氰化络合物催化二氧化碳-氧化苯乙烯的共聚

以钴锌双金属氰化络合物(Co-Zn DMC)为催化剂,高催化效率地合成了CO_2/StO二元共聚物,以及CO_2/StO/CHO三元共聚物,并对催化剂和聚合产物用元素分析、红外光谱(IR)、核磁共振(~1H-NMR)等进行表征。二元共聚催化效率高达3600 g Polym/g Cat,碳酸酯键含量达94.5%,(?)n=13000 g/mol,分子量分布PDI=1.29;三元共聚催化效率为890 g Polym/g Cat,碳酸酯键含量为92.6%,(?)_n=16700 g/mol,PDI=1.61。通过热重分析(TG)和差示扫描量热分析(DSC)研究了聚合产物的热性能,三元共聚物的T_g较聚碳酸苯亚乙酯提高了10℃左右,其碳酸酯键热分解温度都比相应的二元共聚物有所降低。     

高交替度聚碳酸亚环己酯的合成与热性能

文中用SalenAl(OiPr)作催化剂,并以路易斯碱为共催化剂,催化二氧化碳与氧化环己烯共聚得到了高产率高交替度(碳酸酯键含量>99%)的聚碳酸亚环己酯。用1H-NMR、IR、DSC、TG等对共聚产物进行了结构性能的分析和表征。DSC和TGA结果表明,该高交替度聚碳酸亚环己酯的玻璃化转变温度(Tg)为135℃,在280℃左右开始分解,350℃完全分解。并讨论了碳酸酯键含量对共聚物的热分解性能的影响,进一步表明了碳酸酯含量高的共聚物具有热分解的彻底性。     

Photocatalytic decomposition of acephate in irradiated TiO2 suspensions

In the present study, the photocatalytic degradation of acephate (O,S-dimethyl acetyl phosphoramidothioate ((CH(3)O)(CH(3)S)P(O)NHCOCH(3))) in aqueous TiO2 suspensions is extensively investigated, pertaining to the concentration of photocatalyst and substrate on degradation rate of acephate. It is found that the acephate can be degradated and mineralized. The high-degradation rate is obtained with 4 g/L concentration of TiO2. Moreover, Langmuir-Hinshelowood rate expression is employed for the degradation of acephate with adsorption constant and rate constant, i.e., 2.0 L/mmol and 0.6 mmol/(min L), respectively. The main target is to identify the products by a number of analytical techniques, such as HPLC, IC, ESR and GC-MS. Under acidic condition, the primary products are phosphorothioic acid, O,O',S-trimethyl ester (CH(3)O(CH(3)S)P(O)OCH(3)) and phosphoramidothioic acid, O,S-dimethyl ester (CH(3)O(CH(3)S)P(O)NH(2)), etc. It indicates that the decomposition of acephate begin from the destruction of C-N and P-N bonds. Subsequently, the P-S, P-O, P-C bonds may be oxidized gradually or simultaneously, and the final products such as CO(2), H(3)PO(4), were formed. About 100% sulfur atoms are transformed into SO(4)(2-) in 180 min, however; only 3% nitrogen atoms and 2% phosphorus atoms were transformed into NO(3)(-) and PO(4)(3-).     

A promising codrug of nicotinic acid and ibuprofen for managing dyslipidemia. I: synthesis and in vitro evaluation

Nicotinic acid is therapeutically the optimum antihyperlipidemic agent, yet its intolerable cutaneous flushing hinders its wide clinical implication. The codrug of nicotinic acid and ibuprofen (IBP) was synthesized in the aim of overcoming the troublesome side effect of nicotinic acid by blockade of prostaglandin synthesis through released IBP, thus enhance patient's compliance. The physico-chemical properties of codrug namely solubility, partition coefficient, and pKa were determined. Its solubility in aqueous and organic solvents was highest in 0.1 M HCl and isopropanol, respectively. The kinetics of hydrolysis of the codrug and IBP 2-hydroxyethyl ester was studied in aqueous phosphate buffer solution in pH 1.2, 6.8, and 7.4 at 70°C, 80°C, and 90°C. The hydrolysis was found to be pH dependent and followed Arrhenius equation. The half-life of codrug and IBP 2-hydroxyethyl ester at 25°C in pH 7.4 was 218 days and 3 years, respectively. In vitro enzymatic hydrolysis of codrug and IBP 2-hydroxyethyl ester was studied in human plasma and rat liver homogenate. Codrug and IBP 2-hydroxyethyl ester exhibited faster in vitro enzymatic hydrolysis than in vitro chemical hydrolysis. The pseudo-first-order rate constants were 0.0113, 0.177 min(-1) for codrug and 0.0006, 0.0569 min(-1) for IBP 2-hydroxyethyl ester in human plasma and rat liver homogenate, respectively. Thus, nicotinic acid will be rapidly released from codrug to manage dyslipidemia, followed by the later release of IBP from IBP 2-hydroxyethyl ester to alleviate nicotinic acid cutaneous flushing.     

A promising codrug of nicotinic acid and ibuprofen for managing dyslipidemia. I: Synthesis and in vitro evaluation

Nicotinic acid is therapeutically the optimum antihyperlipidemic agent, yet its intolerable cutaneous flushing hinders its wide clinical implication. The codrug of nicotinic acid and ibuprofen (IBP) was synthesized in the aim of overcoming the troublesome side effect of nicotinic acid by blockade of prostaglandin synthesis through released IBP, thus enhance patient’s compliance. The physico-chemical properties of codrug namely solubility, partition coefficient, and pKa were determined. Its solubility in aqueous and organic solvents was highest in 0.1?M HCl and isopropanol, respectively. The kinetics of hydrolysis of the codrug and IBP 2-hydroxyethyl ester was studied in aqueous phosphate buffer solution in pH 1.2, 6.8, and 7.4 at 70°C, 80°C, and 90°C. The hydrolysis was found to be pH dependent and followed Arrhenius equation. The half-life of codrug and IBP 2-hydroxyethyl ester at 25°C in pH 7.4 was 218 days and 3 years, respectively. In vitro enzymatic hydrolysis of codrug and IBP 2-hydroxyethyl ester was studied in human plasma and rat liver homogenate. Codrug and IBP 2-hydroxyethyl ester exhibited faster in vitro enzymatic hydrolysis than in vitro chemical hydrolysis. The pseudo-first-order rate constants were 0.0113, 0.177?min^?1 for codrug and 0.0006, 0.0569?min^?1 for IBP 2-hydroxyethyl ester in human plasma and rat liver homogenate, respectively. Thus, nicotinic acid will be rapidly released from codrug to manage dyslipidemia, followed by the later release of IBP from IBP 2-hydroxyethyl ester to alleviate nicotinic acid cutaneous flushing.     

Oligoesters and polyesters produced by the curing of sunflower oil epoxidized biodiesel with cis-cyclohexane dicarboxylic anhydride: Synthesis and characterization

Oligoesters and polyesters produced from sunflower oil biodiesel were synthesized and characterized. The polymers were obtained through the reaction of fatty acid methyl epoxy esters (EE) with cis-1,2-cyclohexane dicarboxylic anhydride (CH) and triethylamine (TEA) as initiator. Some reactions were conducted by adding small amounts of 1,4-butanediol diglycidyl ether (BDGE). The intermediate products of the synthesis process, including sunflower oil, methyl ester, epoxidised methyl esters, and the oligoesters and polyesters produced, were followed by Fourier Transform Infrared Spectroscopy and ¹H and ¹³C nuclear magnetic resonance. The products obtained from the curing of the epoxidised esters with different compositions present similar chemical structures; however, they still depend on the amount of the epoxy resin BDGE that was added in the polymerization reaction. Thermoplastic materials with molecular weights (MW) starting at 3800 g/mol and reaching very high MWs, resulted in cross linked polymers. The thermal behaviour of the different products was investigated using differential scanning calorimetry and thermogravimetric analyses. The presence of BDGE in the structure of the materials increases the bonding capacity, resulting in higher molecular weight materials, which present good thermal stability.     

The polymerization products of epoxidized oleic acid and epoxidized methyl oleate with cis-1,2-cyclohexanedicarboxylic anhydride and triethylamine as the initiator: Chemical structures,thermal and electrical properties

Oligo and polyesters were prepared from epoxidized oleic acid (EOA) and methyl oleate (EMO) in polymerization reaction with cis-1,2-cyclohexanedicarboxylic anhydride (CH) and triethylamine (TEA) as the initiator at 165 °C for 3 h. In order to increase the molecular weight of the products, a small amount of butanodiol diglycidil ether (BDGE) was added. The different steps of the reactions were elucidated by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). These same techniques as well as size exclusion chromatography (SEC), thermogravimetric analysis (TGA) and electric impedance spectroscopy (EIS) were used to characterize the products of the EMO/CH/TEA, EMO/CH/BDGE/TEA, EOA/CH/TEA and EOA/CH/BDGE/TEA reaction systems. The formation of internal ester groups was confirmed by NMR and FTIR. The Mw products are between 2500 g/mol and 85000 g/mol. The ΔΗ values are 44.6 KJ/ee and 42.7 KJ/ee for the EOA and EMO systems, respectively. The thermal degradations of the products start at temperatures higher than 180 °C. All of the products reveal glass transitions between ? 57 °C and ? 14 °C, while the EMO ones also present crystallization-like behavior at ? 7 °C and 3 °C. The dielectric properties of the products include very high resistivity and low capacitance.     

Photochemical reduction of CO₂ using TiO₂: effects of organic adsorbates on TiO₂ and deposition of Pd onto TiO₂

Reduction of CO(2) using semiconductors as photocatalysts has recently attracted a great deal of attention again. The effects of organic adsorbates on semiconductors on the photocatalytic products are noteworthy. On untreated TiO(2) (P-25) particles a considerable number of organic molecules such as acetic acid were adsorbed. Although irradiation of an aqueous suspension of this TiO(2) resulted in the formation of a significant amount of CH(4) as a major product, it was strongly suggested that its formation mainly proceeded via the photo-Kolbe reaction of acetic acid. Using TiO(2) treated by calcination and washing procedures for removal of the organic adsorbates, CO was photocatalytically generated as a major product, along with a very small amount of CH(4), from an aqueous suspension under a CO(2) atmosphere. In contrast, by using Pd (>0.5 wt %) deposited on TiO(2) (Pd-TiO(2)) on which organic adsorbates were not detected, CH(4) was the main product, but CO formation was drastically reduced compared with that on the pretreated TiO(2). Experimental data, including isotope labeling, indicated that CO(2) and CO(3)(2-) are the main carbon sources of the CH(4) formation, which proceeds on the Pd site of Pd-TiO(2). Prolonged irradiation caused deactivation of the photocatalysis of Pd-TiO(2) because of the partial oxidation of the deposited Pd to PdO.     

环梯形聚苯基硅倍半氧烷的硝化研究

为了提高环梯形聚苯基硅倍半氧烷(Cyclic Ladder Polyphenylsilsesquioxane,CL-PPSQ)在聚合物中的相容性,使用多种硝化试剂,包括发烟硝酸、HNO_3-H_2SO_4、KNO_3-H_2SO_4、HNO_3-KNO_3、CH_3COOH-KNO_3、(CH_3CO)_2O-HNO_3,在不同的条件下对其进行硝化,制备得到含硝基基团的NO_2-PPSQ。使用FTIR、元素分析、GPC、TGA、~1 H NMR等对硝化产物进行表征。结果表明:发烟硝酸、HNO_3-H_2SO_4、KNO_3-H_2SO_4对CL-PPSQ的硝化能力最强,产物中硝基数目最多,但产物分子量降低,硅氧烷链段发生断裂;而HNO_3-KNO_3和CH_3COOH-KNO_3对CL-PPSQ没有硝化能力;(CH_3CO)_2O-HNO_3硝化过程温和,硝化能力适中,制备得到分子链不断裂的硝化产物。对不同硝化试剂的硝化机理进行了分析,在发烟硝酸、HNO_3-H_2SO_4、KNO_3-H_2SO_4体系中,NO_2~+为硝化活化剂;对于(CH_3CO)_2O-HNO_3体系,CH_3COONO_2为主要的硝化活化剂。     

聚碳硅烷纤维氧化交联机理的研究

对聚碳硅烷(PCS)原丝在不同氧化交联温度区间生成的逸出产物进行红外、核磁和GC-MAS分析,并结合交联丝的红外分析,推测氧化交联的机理。结果表明,PCS的氧化交联主要是其Si—H氧化生成Si—OH,后者进而彼此缩合生成Si—O—Si交联结构;氧化交联温度高于150℃时,其部分Si—CH3也开始氧化生成Si—OH并进而交联;同时,在氧化交联过程还发生PCS侧链的热裂解,所形成小分子也通过Si—OH彼此结合,形成较大分子,且其分子量随交联温度的提高而提高。因此,要及时排除氧化交联过程废气,以免逸出产物黏附在纤维表面而导致粘结。     

微弧氧化生成钛酸盐系铁电薄膜研究

为开发新的铁电薄膜制备工艺,需将Ti板微弧氧化.采用Ba(OH)2、Ba(CH3COO)2、BaCl2、Ba(OH)2+Ba(NO3)2及Pb(CH3COO)2对Ti板进行微弧氧化试验,并对生成的薄膜进行物相组成和显微形貌的分析.结果表明:Ti板在BaCl2、Pb(CH3COO)2及Ba(OH)2+Ba(NO3)2中不...     

Importance of fundamental sp, sp2, and sp3 hydrocarbon radicals in the growth of polycyclic aromatic hydrocarbons

The most basic chemistry of products formation in hydrocarbons pyrolysis has been explored via a comparative experimental study on the roles of fundamental sp, sp(2), and sp(3) hydrocarbon radicals/intermediates such as ethyne/ethynyl (C(2)H(2)/C(2)H), ethene/ethenyl (C(2)H(4)/C(2)H(3)), and methane/methyl (CH(4)/CH(3)) in products formations. By using an in situ time-of-flight mass spectrometry technique, gas-phase products of pyrolysis of acetylene (ethyne, C(2)H(2)), ethylene (ethene, C(2)H(4)), and acetone (propanone, CH(3)COCH(3)) were detected and found to include small aliphatic products to large polycyclic aromatic hydrocarbons (PAHs) of mass 324 amu. Observed products mass spectra showed a remarkable sequence of mass peaks at regular mass number intervals of 24, 26, or 14 indicating the role of the particular corresponding radicals, ethynyl (C(2)H), ethenyl (C(2)H(3)), or methyl (CH(3)), in products formation. The analysis of results revealed the following: (a) product formation in hydrocarbon pyrolysis is dominated by hydrogen abstraction and a vinyl (ethenyl, C(2)H(3)) radical addition (HAVA) mechanism, (b) contrary to the existing concept of termination of products mass growth at cyclopenta fused species like acenaphthylene, novel pathways forming large PAHs were found succeeding beyond such cyclopenta fused species by the further addition of C(2)H(x) or CH(3) radicals, (c) production of cyclopenta ring-fused PAHs (CP-PAHs) such as fluoranthene/corannulene appeared as a preferred route over benzenoid species like pyrene/coronene, (d) because of the high reactivity of the CH(3) radical, it readily converts unbranched products into products with aliphatic chains (branched product), and (e) some interesting novel products such as dicarbon monoxide (C(2)O), tricarbon monoxide (C(3)O), and cyclic ketones were detected especially in acetone pyrolysis. These results finally suggest that existing kinetic models of product formation should be modified to include the reported novel species and their formation pathways. It is expected that outcomes of this study will be useful to understand the products formation from reactors to interstellar atmospheres as well as the growth mechanism of carbon nanomaterials.