~1H-NMR谱表征聚异戊二烯和聚间戊二烯及异戊二烯间戊二烯共聚物的微观结构

利用400 MHz高分辨率核磁共振氢谱,首先对聚异戊二烯橡胶和聚间戊二烯橡胶的微观结构分别进行分析,进而对异戊二烯-间戊二烯共聚物的微观结构进行了研究,建立了聚异戊二烯、聚间戊二烯以及异戊二烯间戊二烯共聚物微观结构的核磁共振氢谱分析方法。     

硫化反式聚异戊二烯电子性质的理论化学研究

应用量子化学计算方法,对反式聚异戊二烯本征态和硫化态结构的能量及电子性质等进行了计算.结果表明,当聚异戊二烯掺杂硫后,相邻两链之间的距离a⊥变窄,体系的总能量降低,从而使整个掺杂体系更加稳定.另外,在硫化聚异戊二烯分子中,S原子位于两个相邻聚异戊二烯链之间,并偏向于其中一个分子链的C C双键的一侧,即与相邻两链中相对应的两个C C双键形成π-p-π共轭体系,增加了电子在两个聚异戊二烯链间的流动性,从而使硫化的反式聚异戊二烯更加稳定.另外,根据固体能带理论,采用量子化学EHMO方法,对反式聚异戊二烯本征态和硫掺杂态的能带结构进行了计算,根据硫化前后能隙和带宽的变化,解释了反式聚异戊二烯掺杂后呈现电导率各向异性的原因.     

聚异戊二烯在四氯化锡－对甲苯磺酸催化下的环化反应动力学研究

聚异戊二烯在四氯化锡－对甲苯磺酸催化下的环化反应动力学研究孙晓日（山东昌潍师范专科学校化学系，山东潍坊２６１０４３）顾江楠苏翠华余尚先李大珍（北京师范大学化学系，北京１００８７５）关键词聚异戊二烯，环化聚异戊二烯，环化反应，动力学环化聚异戊二烯是聚异...     

聚氨基酸接枝聚异戊二烯的仿生合成与性能

通过硫醇-烯点击反应将2-氨基乙硫醇接枝到聚异戊二烯主链上合成带有氨基侧链的聚异戊二烯,再通过侧链氨基引发L-缬氨酸-N-硫代羧基内酸酐(Val-NTA)单体和β-苯丙氨酸-N-硫代羧基内酸酐(β-Phe-NTA)单体的聚合,制备出2种方式改性的聚异戊二烯.其中,Val-NTA聚合接枝聚异戊二烯的拉伸强度28.6 MPa,300%定伸强度18.9 MPa,相比天然橡胶分别提升10.7%和9.3%. β-Phe-NTA聚合接枝聚异戊二烯的拉伸强度28.0 MPa,比天然橡胶提升8.3%.     

光敏剂存在下3,4-聚异戊二烯的光交联反应

本文研究了在敏化剂二苯甲酮存在下3,4-聚异戊二烯的光交联反应。发现在80W高压汞灯辐照下,二苯甲酮敏化的3,4-聚异戊二烯能够发生光交联反应,其凝胶含量、交联密度与光照时间、3,4-聚异戊二烯的分子量以及二苯甲酮的用量有关。用FTIR和C¹³NMR证实了该交联反应以外双键的2+2加成为主。     

液体聚异戊二烯的合成与应用研究进展

固态橡胶具有较高的分子量、强度及伸长率,在工业和日常生活中均得到广泛应用.然而,固态橡胶黏度较高,在应用中往往必须引入添加剂.而液体聚异戊二烯是一种液态橡胶,可以作为固态橡胶的软化剂;得益于其特殊的形态和性能,液体聚异戊二烯可望在多方面得到应用.对液体聚异戊二烯的合成与应用进行了评述.     

基于聚异戊二烯嵌段共聚物的研究进展

含异戊二烯结构单元的嵌段共聚物,以其优异的性能,在自组装材料和纳米尺寸材料等领域得到了日益广泛的关注和研究。本文从合成的角度出发,系统地综述了聚异戊二烯嵌段共聚物的制备方法,特别介绍了基于聚异戊二烯嵌段合成的阴离子聚合以及活性自由基聚合中的氮氧自由基聚合(NMRP)、可逆加成-断裂链转移自由基聚合(RAFT)、原子转移自由基聚合(ATRP)等聚合方法。以可控聚合为基础的多种聚合技术综合运用是制备聚异戊二烯嵌段共聚物未来的发展方向。     

反式-/顺式-1,4-聚异戊二烯共混体系的结晶动力学

采用差示扫描量热(DSC)法对反式-/顺式-1,4-聚异戊二烯共混体系的等温及非等温结晶动力学进行了研究,分别采用Avrami方程和莫志深法对其动力学参数进行了解析.研究结果表明,在反式-/顺式-1,4-聚异戊二烯共混体系的等温及非等温结晶过程中,顺式-1,4-聚异戊二烯(CPI)组分的存在会降低反式-1,4-聚异戊二烯(TPI)组分的结晶速率;在等温结晶过程中,CPI组分会提高TPI组分自身的结晶度;而非等温结晶过程中,CPI则提高了共混物中β晶型的相对含量.     

3,4-聚异戊二烯的磺化反应及其离聚体的结构研究

本工作合成了磺化的3,4-聚异戊二烯及其离子聚合体,IR和NMR谱图证明对3,4-聚异戊二烯的磺化反应是成功的,并且磺酸基团主要与3,4-链节的侧基双键发生反应。WAXD对磺化3,4-聚异戊二烯及其离聚体的研究表明,磺化度的增加使离聚体的结晶能力降低,SAXS结果表明,在离子含量为3.29mol％的离聚体中,未观察到离子簇聚集,只观察到多重离子对的散射。     

杜仲胶玻璃化转变温度的分子模拟

对杜仲胶的玻璃化转变温度进行了分子动力学模拟。首先,计算了不同聚合度的反式聚异戊二烯的溶度参数,确定了合理的反式聚异戊二烯结构模型的聚合度为20;然后,用分子动力学模拟获得反式聚异戊二烯在不同温度下的比体积,通过对模拟得到的比体积-温度(V-T)作图,求得玻璃化转变温度(Tg)为210 K,采用差示扫描量热(DSC)法实测得到的Tg为203 K,两种结果在误差允许范围内基本一致,其模拟结果与实测值吻合得较好。     

亲水相互作用色谱柱串联C18柱高效分析饮品中的胭脂红

建立了亲水相互作用色谱柱(HILIC)串联C18柱的方法,高效分离实际样品中的胭脂红,并对色谱柱的串联顺序以及色谱分离条件进行优化。结果表明:当HILIC柱在前C18柱在后,流动相为乙腈-乙酸铵(5 mmol/L)=91∶9(V/V),流速为0.9 mL/min,柱温为25℃,检测波长为508 nm时,此时胭脂红的分离效果最佳。在最佳的色谱分离条件下,选用两种市售饮品进行实际样品的测定,回收率在81.2%~119%。方法适用于水相样品中的强极性物质的高效分离与分析。     

纳米催化剂在CO_(2)加氢制甲醇中的研究进展北大核心CSCD

为减缓温室效应,将CO_(2)转换成高附加值的甲醇是减少CO_(2)排放的有效途径,而高效催化剂是CO_(2)加氢制甲醇反应规模化的关键.可调控合成的具有量子尺寸效应的纳米催化剂在该反应上具有独特的优势.因此我们深入探讨了反应机理,综述了纳米材料在CO_(2)加氢制甲醇中的研究进展,最后给出了高效催化剂可能的发展方向.     

HPLC study of tissue distribution of loganin in rats

A rapid, sensitive and selective high performance liquid chromatography (HPLC) method was developed and validated for determination of loganin in rat tissues. Samples were prepared based on a simple protein precipitation. Separation of loganin was achieved on a reversed-phase C(18) column (250 x 4.6 mm, 5 microm) with a mobile phase consisting of acetonitrile and water (16:84, v/v) at a flow rate of 1.0 mL/min. The detection wavelength was set at 236 nm and the temperature of the column was kept at 30 degrees C. The method was applied to study tissue distribution of loganin in rats after a single administration of loganin at a dose of 20 mg/kg. The highest level was observed in kidney, then in stomach, lung and small intestine. The lowest level was found in brain. The peak levels were attained at 90 min in most tissues. It was indicated that kidney was the major distribution tissue of loganin in rats, and that loganin had difficulty in crossing the blood-brain barrier. It was also found there was no long-term accumulation of loganin in rat tissues.     

Dissolution and bioavailability of phenobarbital in solid dispersion with phosphatidylcholine.

The dissolution of phenobarbital (PB) from solid dispersion with phosphatidylcholine (PC) was studied. PB was present in an amorphous state in solid dispersion (PB-PC) if the mole fraction of PB was under 0.75. Thus, supersaturation was observed when an excess amount of PB-PC was dispersed in pH 1.2 and 6.8 media. The degree of supersaturation was largest when the mole fraction of PB was 0.25, although it was only 1.3-fold of the PB solubility in this case. Dissolution from PB-PC was rapid and complete in both pH 1.2 and 6.8 media regardless of the mole fraction of PB, above 90% within 5 min. Bioavailability after the oral administration of PB-PC to rabbits with a dose of 15 mg/kg equivalent to PB was compared with that of PB crystals. The area under the plasma concentration curve was bigger, but not significant. The maximum concentration was significantly higher, and the time to maximum concentration was significantly faster. These results indicate that the absorption rate became high with PB-PC because the dissolution was rapid.     

Extraction and separation of cationic surfactants from river sediments: application to a spectrophotometric determination of cationic surfactant in an aquatic environment using membrane filters.

The quantitative extraction of cationic surfactant (CS+) in river sediments was studied. Further, the developed method was applied to the spectrophotometric determination of CS+ in urban river sediment samples by solid-phase extraction with membranes. A mixture of methanol and hydrochloric acid was proposed as an eluent. Dried sediment was digested in the eluent under ultrasonic irradiation. After elution, the eluent was evaporated to almost dryness. The residue was dissolved in a small volume of methanol and diluted to a certain volume with water. The pH of the solution was adjusted to 4-5 to separate iron and some other metals as precipitates of hydroxides. The solution was passed through two-piled membranes: first glass-fiber and then polytetrafluoroethylene (PTFE) membranes. A small volume of methanol was passed through the membranes to elute any CS+ retaining on the membranes. After passing the methanol solution through a cationic exchange resin column, the retained CS+ was eluted with methanol containing a high concentration of sodium chloride. Water, Bromophenol Blue (BPB) and hydrochloric acid were added to the solution. The solution was passed through a mixed cellulose ester membrane filter to retain an ion associate of CS+.BPB-. The retained ion associate was dissolved in a small volume of N,N-dimethylformamide together with the membrane filter, followed by the addition of triethanolamine to make the solution alkaline. The absorbance due to BPB2- was measured at 603 nm against a reagent blank. This method was applied to the determination of CS+ in river water and sediment. A cationic surfactant in sediments at 10(-5) mol kg-1 levels was detected with satisfactory precision. It was found that CS+ was about 500-fold enriched in the sediment from water at the place where domestic wastewater was discharged.     

有机颜料与表面活性剂DBS混合物的光催化降解

以TiO₂为光催化剂,研究了表面活性剂十二烷基苯磺酸钠(DBS)和有机颜料耐晒大红BBN(BBN)为混合组分的光催化降解,结果表明,pH值、底物的用量对体系的降解有显著影响,在碱性条件下,DBS的降解速率相对较快,而在酸性环境时,颜料的降解较快,在TiO₂等电点时,降解最慢,酸性条件下, TiO₂对BBN和DBS的吸附性比在碱性和中性环境中大,BBN/DBS体系中, DBS增大了BBN的水溶性,但是没有明显提高BBN的降解褪色速度,DBS浓度为0.42 g/L时,颜料降解最快,0.042 g/L时次之,2.1 g/L时最低,在BBN降解过程中DBS自身也被降解,且略有促进作用。     

A New Capillary Electrophoresis Apparatus with Piezoelectric Ceramics High Voltage Source and Amperometric Detector

IntroductionHighperformancecapiliar}'electrophoresis(HPCE)isanewanalyticaltechnology'rapidly'developedinrecentyears.Withtheadvantagesofsmallsample.highsensitivity,highresolution.rapidanalysisandverycheaprunning,ithasbeenappliedinchemistry'.lifescienc...     

高效液相色谱梯度法测定雷公藤制剂中雷公藤甲素的含量

采用高效液相色谱梯度法分离测定雷公藤制剂中雷公藤甲素的含量,用国产YWG色谱柱分离,二极管阵列检测器检测,所得三维光谱与空白光谱进行差减,取波长218nm处色谱图积分,定量。与等度法比较,梯度法具有更高的分离度、灵敏度,测定雷公藤口服液中雷公藤甲素的质量浓度为202．0μg／L,每片雷公藤片剂含甲素11．74μg,结果显著低于等度法和标示量（P<0．05）。     

头发微量元素及钙含量测定的应用价值评价

以125例2～5岁儿童为对象，测定其全血和头发铅、锌、铁、钙含量；以全血铅、锌、铁、钙含量为标准，应用诊断试验评价方法评价头发铅、锌、铁、钙测定的应用价值。结果表明，头发铅测定的灵敏度可达88．3％，应用串联试验，头发铅测定的特异度可提高至81．8％，阳性预测值达69．6％，阴性预测值达78．8％。头发锌测定的灵敏度可达86．1％，特异度为52．4％，阳性预测值75．6％，阴性预测值为68．8％。头发铁测定的灵敏度为72．0％，特异度为77．5％，阳性预测值为83．6％，阴性预测值为63．3％，头发钙测定的灵敏度为78．9％，特异度为69．1％，阳性预测值为69．8％，阴性预测值为78．4％。锌缺乏、铁缺乏、钙缺乏，或铅负荷过高，或数种微量元素缺乏及铅中毒并存是当前严重影响儿童健康成长的常见原因。运用现代检测技术早期发现微量元素缺乏及铅中毒患儿并及时采取防治措施对促进儿童正常生长发育至关重要。头发样品容易采集、运送和保存，因此头发微量元素含量测定适合在中小城镇及农村使用。但其应用价值应进行科学评价。     

Ag-Sn合金的氧化过程与热力学性质

采用密度泛函微扰理论(DFPT)计算了Ag-Sn-O体系中O原子在Ag-Sn合金中的运动与反应, 及该体系中几种化合物的结合能、生成焓以及热容与自由能随温度的变化. 计算发现O原子存在于Ag晶格的四面体间隙, 若存在八面体间隙会使体系能量升高288.23 kJ·mol-1; Sn则在Ag晶格中主要以置换形式存在. 计算得到结合能大小顺序为Ag6O2>SnO2>Ag2SnO3>SnO>Ag2O. SnO2的稳定性最高, 生成焓约-591.1 kJ·mol-1, SnO是一种过渡相, 而Ag2SnO3和Ag6O2为亚稳相, 都能在常温下存在, 这与相关实验结果一致. 原子间相互作用曲线说明Sn—O的成键能力明显高于Ag—O, 氧化时只会形成Sn—O键. 准谐函数近似计算(QHA)表明Ag2SnO3的热容远高于其它化合物, 其德拜温度约500 K, 升温能力仅为SnO2的1/3, 可有效解决AgSnO2电接触材料中温升过快的问题, 而布居分布和Gibbs自由能则进一步说明SnO2是Ag-Sn-O体系中最稳定的相.