不同次级结构的硫酸钡多晶体制备研究

以过氧化钡(Ba O2)晶体为母体钡源,利用溶液中碱性条件下过氧化氢电离控制Ba O2分解速度,结合过量SO42-制备了具有Ba O2宏观形貌的Ba SO4多晶体,该多晶体由条形结构单元组成。进一步通过不同聚合物添加剂调节次级结构单元的形貌,在溶液中引入聚苯乙烯磺酸钠制备了由球形次级结构单元组成的Ba SO4多晶体;而在不同浓度的聚丙烯酸添加剂作用下,可制得由纳米颗粒和纳米棒状结构单元组成的Ba SO4多晶体。制备的多晶体材料为具有母体材料统一宏观形貌的大颗粒,其次级结构可通过聚合物添加剂调控,为合成具有特定形貌的功能晶体材料提供了一个新的途径。     

白果形钨酸铅的可控合成及光致发光特性

以酒石酸钠为表面活性剂,采用直接沉淀法合成了白果形钨酸铅晶体,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、能量散射仪(EDS)及荧光发射光谱(PL)对产物的结构和性质进行了表征。探讨了酒石酸钠对(004)晶面的抑制作用以及pH值和陈化温度对产物形貌的影响,结合晶体的内部结构提出了产物可能的形成机制。结果表明,陈化温度为30℃时,晶体形貌最为规整,PbWO4晶体在紫外光激发下展现出强的绿光发射,在pH=9时可达到最大的发光强度。     

仲钨酸铵的制备及研究

通过对比蒸发法与在蒸发法中添加晶种和钨酸铵溶液制备的仲钨酸铵产品,结果表明后者制备的晶形更完整、颗粒较粗,且是纯度更高的5水仲钨酸铵.对产品进行了X射线衍射分析与热重分析,并探讨了仲钨酸铵成核机制、动力学过程.最后讨论了添加晶种和钨酸铵溶液对晶体形貌的影响.     

白果形钨酸铅的可控合成及光致发光特性

以酒石酸钠为表面活性剂,采用直接沉淀法合成了白果形钨酸铅晶体,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、能量散射仪(EDS)及荧光发射光谱(PL)对产物的结构和性质进行了表征。探讨了酒石酸钠对(004)晶面的抑制作用以及pH值和陈化温度对产物形貌的影响,结合晶体的内部结构提出了产物可能的形成机制。结果表明,陈化温度为30℃时,晶体形貌最为规整,PbWO₄晶体在紫外光激发下展现出强的绿光发射,在pH=9时可达到最大的发光强度。     

PI-b-P2VP两嵌段共聚物环状形貌的影响因素研究

基于最近Chang等在嵌段共聚物聚异戊二烯-聚2-乙烯基吡啶(PI-b-P2VP)的四氢呋喃-乙醇共混溶剂体系制备环状胶束的工作(Angew. Chem. 2009, 48, 4594), 我们在此基础上, 用原子力显微镜对该体系形成环状结构的影响因素包括嵌段共聚物浓度、混合溶剂配比、溶剂选择性、溶剂挥发速度、溶剂滴加顺序及选择性溶剂的滴加速度等进行了详细研究, 发现P2VP的选择性溶剂的引入是形成环状结构的关键因素. 利用P2VP与氯金酸的络合, 分析环状结构, 并进一步结合动、静态光散射及冷冻透射电镜对此形貌的形成机理进行探究.     

聚4-乙烯基吡啶与Cu(Ⅱ)离子配合过程及配合物的结构

采用粘度法确定了聚4-乙烯基吡啶(P4VP)在乙醇/水混合溶剂中的临界交迭浓度c*, 分别在稀溶液与亚浓溶液浓度范围内, 采用光谱法与电导滴定法研究了P4VP与Cu(II)离子的配合过程及配合物的结构, 通过红外光谱(FTIR)对配合物的化学结构进行了表征, 并用差示扫描量热法(DSC)测定了配合物的热性能. 结果表明, 对于相对分子质量为1.06×105的P4VP, 其c*为15 mmol•L−1(按P4VP中的链节量计算). 在稀溶液中P4VP与Cu(II)离子形成可溶性的分子内配合物, 表观配位数为9~10；在亚浓溶液中, P4VP与Cu(II)离子发生分子间配合作用, 由于配位交联, 形成不溶性的配合物P4VP-Cu(II), 配位数为3. P4VP与Cu(II)离子形成配合物后, 玻璃化温度明显提高.     

不同形状的钨酸钡纳米粒子的合成

不同形状的钨酸钡纳米粒子的合成;微乳液;钨酸钡;纳米粒子;十二胺;十一烯酸     

辐射陷阱效应对钨酸镧晶体中Yb3+光谱性质的影响

采用提拉法获得了Yb3 :La2(WO4)2晶体,并测量了该晶体的室温吸收光谱.为了分析辐射陷阱效应对Yb3 光谱性质的影响,分别测量了块状和粉末状晶体样品的荧光光谱和荧光衰减曲线.研究结果表明:辐射陷阱效应导致钨酸镧晶体中Yb3 离子的荧光光谱、受激发射截面和荧光寿命等光谱性质发生了明显的变化.     

十二烷基苯磺酸钠对碳酸钙结晶行为的影响

以CaCl_2和(NH_4)_2CO_3为原料,以十二烷基苯磺酸钠(SDBS)为模板剂,采用气体扩散法制备了CaCO_3颗粒,研究了溶液中不同浓度SDBS对Ca CO_3结晶行为及形貌特征的影响.扫描电子显微镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FTIR)表征结果表明,当溶液中不添加SDBS时,Ca CO_3样品主要为方解石型晶体,呈规则菱形六面体形貌;当溶液中添加SDBS时,CaCO_3样品主要以球霰石型晶体存在,呈球形.这说明在溶液中添加SDBS可以改变CaCO_3的结晶生长方式.随着溶液中SDBS浓度增加,所生成的CaCO_3样品中球霰石型晶体相对含量逐渐增加.当SDBS浓度为1. 2×10-3mol/L时,样品中几乎全部为球霰石型晶体.继续增加溶液中SDBS浓度,由于胶束形态改变和稳定性变差,样品中亚稳态的球霰石型晶体向稳定的方解石型晶体转变,球霰石型晶体相对含量逐渐减少,并呈现花形、六边形和纺锤形等多种形貌特征.     

基于温度/pH双响应的聚合物表面活性剂调控嵌段共聚物微球形貌

研发响应多重外界刺激而改变形貌的嵌段共聚物微球对发展新型智能材料具有重要意义.本工作提出了一种温度/pH双响应嵌段共聚物微球形貌转变的策略.在利用乳液挥发法制备聚苯乙烯-b-聚(4-乙烯基吡啶)(PS-b-P4VP)微球时,引入温度/pH双响应的聚丙烯酸-b-聚(N-异丙基丙烯酰胺)(PAA-b-PNIPAM)作为表面活性剂,通过调控实验温度以及水相的pH值,实现了PS-b-P4VP微球在蚕蛹状、草莓状、洋葱状等形貌之间的转变.这种独特的形貌转变依赖于温度/pH调控的PAA-b-PNIPAM的亲疏水性转变,以及由此导致的表面活性剂在界面分布位置的改变,进而改变了油水界面的界面选择性以及微球的形貌.通过改变PAA-b-PNIPAM的质量分数、PAA和PNIPAM的嵌段比,系统地研究了温度/pH对PS-b-P4VP微球形貌转变机制的影响.提供了一种温度/pH双响应的微球形貌转变的策略,有望在药物释放、智能传感等领域发挥重要作用.     

亚微米级Cu0/Fe3O4复合物多相催化过一硫酸盐降解有机污染物

过一硫酸盐催化活化技术因其可产生强氧化性活性氧化物种,可快速氧化降解并矿化有机污染物的优异性能而备受关注.本文成功制备了亚微米级Cu0/Fe3O4复合物,发现其能多相催化过一硫酸盐产生单线态氧降解有机污染物.首先,以CuCl2·2H2O,FeCl2·4H2O和FeCl3·6H2O为铜源和铁源,水合肼为还原剂,采用水热法在180oC反应24 h制备了亚微米级磁性Cu0/Fe3O4复合物.表征结果显示,所制材料为Cu0和Fe3O4的复合物,颗粒大小约为220 nm;单一相Cu0和Fe3O4晶体粒径分别为33.8和106.2 nm,而Cu0/Fe3O4复合物中Cu0和Fe3O4晶体粒径分别减为20.8和31.9 nm.这表明Cu0和Fe3O4复合降低了Cu0和Fe3O4晶体粒径,有利于Cu0和Fe3O4的分散.BET测试结果表明,Cu0/Fe3O4复合物比表面积为4.6 m2/g,与Cu0颗粒的(4.2 m2/g)相当,但远小于Fe3O4的(15.6 m2/g).制备的Cu0/Fe3O4复合物可有效催化过一硫酸盐产生单线态氧降解罗丹明B、亚甲基蓝、金橙II、苯酚和对氯酚.当Cu0/Fe3O4复合物的用量为0.1 g/L,过一硫酸盐浓度为0.5 mmol/L和初始pH为7时,Cu0/Fe3O4复合物可在30 min内完全降解20μmol/L的罗丹明B、亚甲基蓝、金橙II以及0.1 mmol/L的苯酚和对氯酚.对比试验显示,在相同条件下,Cu0和Fe3O4颗粒分别可以降解28%和20%的罗丹明B.这表明Cu0/Fe3O4复合物中的Cu0和Fe3O4晶体在催化过一硫酸盐降解污染物的反应中具有协同作用,这主要来源于Cu0/Fe3O4复合物中Cu0和Fe3O4的晶体粒径变小和更好的分散.采用分光光度法测定了降解反应液中铜和铁离子的溶出量.当Cu0/Fe3O4复合物的用量为0.1 g/L,过一硫酸盐浓度为0.5 mmol/L和初始pH为7时,反应60 min后,降解液中铜和铁离子的浓度分别为0.22和0.1 mg/L,仅占复合物中总铜和总铁量的1.1%和0.2%,表明Cu0/Fe3O4复合物具有较强的化学稳定性.所制Cu0/Fe3O4复合物具有超顺磁性,借助磁场实现快速分离回收,可循环利用五次,表明其优越的催化稳定性.通过加入乙醇和叠氮化钠,考察了Cu0/Fe3O4复合物催化活化过一硫酸盐体系中的活性氧化物种.发现100 mmol/L乙醇的加入对污染物的降解无明显影响,而加入同等量的叠氮化钠可完全抑制污染物的降解,表明Cu0/Fe3O4复合物催化活化过一硫酸盐产生的主要活性氧物种为单线态氧.采用电子顺磁共振谱进一步证实了单线态氧的生成.基于以上研究,Cu0/Fe3O4复合物催化活化过一硫酸盐的机理为Cu0/Fe3O4作为一个电子媒介加速过一硫酸盐和污染物之间的电子转移,从而导致污染物被快速降解.该反应机理不同于常见的金属催化过一硫酸盐产生硫酸根和羟自由基的反应机理.我们推测,电导性优良的Cu0在此催化反应中起着关键性作用.本催化方法可作为一种绿色的氧化技术用于环境污染物的氧化降解处理.     

新型重整催化剂的研究—Pt／BaKL型沸石中钡的作用

本文采用XRD,NH_3-TPD,IR以及TEM等方法考察了Pt/BaKL沸石中Ba~(2+)的作用。NH_3-TPD结果表明,交换Ba~(2+)后的L型沸石的酸性,由于阳离子的作用仅在弱酸范围内有些改变,但与载铂的沸石的催化活性无明显的对应关系。IR及XRD谱线表明,BaKL沸石中Ba~(2+)在最佳交换度(26.3%)时,随预培烧温度的提高,使Ba~(2+)处于沸石孔道中B、C、D位置,接近于最佳分布,此时IR谱线上1421cm~(-1)处有一新峰。当沸石负载铂后,因铂与Ba~(2+)的相互作用,新峰消失,导致铂粒在沸石上分布更加均匀;铂粒在1.5—3.0nm之间占有最大比例,使得Pt/BaKL沸石呈现芳构化活性及选择性高于Pt/KL沸石,分别为～98%和～95%。     

Pyranine-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridine) and pH-triggered release of pyranine from the complex micelles

The pyranine-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG114-b-P4VP61) in aqueous solutions and pH-triggered release of pyranine from the complex micelles were studied by dynamic and static light scattering, transmission electron microscopy, 1H NMR spectroscopy, and UV-vis spectroscopy. At pH 2, the ionized pyranine can ionically cross-link the protonated P4VP block and result in well-defined spherical complex micelles with a P4VP/pyranine core surrounded by a PEG corona. The ratio of pyranine to pyridyl units can influence the structure and the properties of the resultant complex micelles. The complex micelles are stable upon dilution and heating but are sensitive to pH changes. pH-triggered release of the incorporated pyranine from the complex micelles demonstrates that the release behavior is pH-tunable and displays good controlled-release characteristics at pH approximately 4.     

Helical poly(3-methyl-4-vinylpyridine)/amino acid complexes: preparation, characterization, and biocompatibility

Helical poly(3-methyl-4-vinylpyridine) (P3M4VP)/amino acid complexes have been prepared via acid-base reaction of the achiral polymer with D and L amino acids: alanine, leucine, valine, serine and phenylalanine. The circular dichroism (CD) spectra of P3M4VP/D- and L-alanine complexes in CH(3)OH/H(2)O show opposing (near mirror image) Cotton effect signals at 278.4, 274.8 and 270.8 nm, indicating the formation of enantiomeric secondary structures. The formation of the enantiomeric structures is supported by observed [alpha](D)(25) values of -3.0 and +3.0 for the P3M4VP/D-alanine and P3M4VP/L-alanine complexes, respectively. The preparation of helical P3M4VP/amino acid complexes has been carried out in CH(3)OH and H(2)O at pH 1.8 and 2.7. The intensities of the Cotton effect signals were good. For example, for the P3M4VP/L-alanine complexes in CH(3)OH/H(2)O and H(2)O (pH 1.8), the second Cotton effect signal around 275-277 nm show [theta;] values of 49 980 and 79 210 deg . cm(2) . dmol(-1), respectively. The formation of the helical secondary structure is rapid. The acid-base reaction between P3M4VP and L-alanine in CH(3)OH/H(2)O, in 10 min, show a CD spectrum with Cotton effect signals at 274 and 272 nm with [theta] values of 27,000 deg . cm(2) . dmol(-1) and -36,000 deg . cm(2) . dmol(-1), respectively. P3M4VP permits ready conformational reorientation on complexation with amino acids, but once the helical P3M4VP/amino acid complexes are formed, it is stable at room temperature. P3M4VP is not compatible with HeLa ovarian cancer cells, but the helical P3M4VP/amino acid complexes are compatible with HeLa cells. The complexes minimally interfere with the adhesion and growth of HeLa cells on complex surfaces. Helical poly(3-methyl-4-vinylpyridine)/D- and L-alanine complexes support the attachment and growth of HeLa cells. The micrographs shows HeLa cells after three days: left panel: on P3M4VP/L-alanine complex; right panel: on P3M4VP/D-alanine complex.     

接枝微粒材料P4VP-SiO_2对酸性氨基酸的吸附性能与吸附机理

将4-乙烯基吡啶(4VP)接枝聚合于微米级硅胶表面,制得了接枝有聚4-乙烯基吡啶(P4VP)的接枝微粒P4VP-SiO_2,测定了P4VP-SiO_2的红外光谱,袁征了其化学结构,并测定了该复合型功能微粒材料的Zeta电位.采用静态法研究了P4VP-SiO_2对酸性氨基酸天冬氨酸与谷氨酸的吸附性能,考察了介质pH、离子强度及温度对其吸附性能的影响,探索了吸附机理.研究结果表明:在较大的pH范围内,P4VP-SiO_2的Zeta电位为较高的正值,即微粒表面携带有高密度的正电荷;酸性氨基酸天冬氨酸与谷氨酸等电点都较低,所以在一般的介质pH范围内,它们的分子带有负电荷;凭借静电相互作用,P4VP-SiO_2对酸性氨基酸天冬氨酸与谷氨酸均表现出很强的吸附能力,而对中性与碱性氨基酸(在一般的介质pH范围内分子带有正电荷)的吸附能力则很弱;随介质pH的增大,P4VP-SiO_2对天冬氨酸与谷氨酸的吸附能力呈现先增强后减弱的规律,在pH＝4处,吸附容量具有最大值,分别为280 mg/g与230 mg/g;温度升高,吸附容量减小;盐度增大,吸附容量降低.     

Preparation of P4VP-g-PSt Copolymer Microspheres with Controllable Size by Atom Transfer Radical Polymerization Synthesized Poly(4-vinylpyridine) Macromonomer

Poly(4‐vinylpyridine) macromonomer (St‐P4VP) with a styryl end group was synthesized by atom transfer radical polymerization (ATRP) of 4‐vinylpyridine using p‐(chloromethyl)styrene (CMSt) as functional initiator, CuCl as catalyst and tris[2‐(dimethylamino)ethyl]amine (Me₆TREN) as ligand in 2‐propanol. The structure of St‐P4VP macromonomer was identified by proton nuclear magnetic resonance (¹H NMR). The result of gel permeation chromatography (GPC) illustrated that the number‐average molecular weight of St‐P4VP could be controlled by adjusting polymerization conditions. Poly(4‐vinylpyridine) grafted polystyrene microspheres (P4VP‐g‐PSt) were then prepared by dispersion copolymerization of styrene with St‐P4VP macromonomers. The effects of polymerization reaction parameters such as medium polarity, concentration of St‐P4VP macromonomer and polymerization temperature on the sizes and size distribution of P4VP‐g‐PSt microspheres were investigated. The results of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and laser light scattering (LLS) indicated that mono‐dispersed P4VP‐g‐PSt microspheres with average diameters of 100–200 nm could be obtained when the molar ratio of St to St‐P4VP was 0.25:100 in ethanol/water mixed solvents (V/V=80:20) at 60°C. Such kind of graft copolymer microspheres was expected to be applied to many fields such as drug delivery system and protein adsorption/separation system due to their particular structure.     

Synthesis and characterization of pH sensitive poly(glycidol)‐b‐poly(4‐vinylpyridine) block copolymers

Block copolymers of poly(glycidol)‐b‐poly(4‐vinylpyridine) were obtained by ATRP of 4‐vinylpyridine initiated by ω‐(2‐chloropropionyl) poly(glycidol) macroinitiators. By changing the monomer/macroinitiator ratio in the synthesis polymers with varied P4VP/PGl molar ratio were obtained. The obtained block copolymers showed pH sensitive solubility. It was found that the linkage of a hydrophilic poly(glycidol) block to a P4VP influenced the pK_a value of P4VP. DLS measurements showed the formation of fully collapsed aggregates exceeding pH 4.7. Above this pH values the collapsed P4VP core of the aggregates was stabilized by a surrounding hydrophilic poly(glycidol) corona. The size of the aggregates depended significantly upon the composition of the block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1782–1794, 2009     

N-硫代酰基硫乙酸功能化三乙撑四胺交联PVC树脂的制备及对Hg~(2+)的吸附

以聚氯乙烯为原料依次与四乙烯五胺、CS_2和ClCH_2COONa反应合成了一种新的含N、O、S的N-硫代酰基硫乙酸功能化三乙撑四胺交联聚氯乙烯螯合树脂,树脂结构经红外分析和元素分析表征. 探讨了在不同pH值、Hg~(2+)初始浓度、吸附温度和时间等条件下合成树脂对Hg~(2+)的吸附性能. 结果表明,螯合树脂对Hg~(2+)有较快的吸附速率,pH值约为2.0时,树脂对Hg~(2+)的吸附效果最好,随温度升高吸附量逐渐增大. 温度在35 ℃、Hg~(2+)起始浓度为17.66 mmol/L时,树脂对Hg~(2+)的吸附量可达3.330 mmol/g. 树脂对Hg~(2+)的吸附符合Langmuir和Freundlich等温式. 用0.2 mol/L HNO3-10%硫脲对吸附后的树脂进行洗脱,脱附率达99.20%.     

Sensitive voltammetric determination of paracetamol by poly (4-vinylpyridine)/multiwalled carbon nanotubes modified glassy carbon electrode

A novel glassy carbon electrode (GCE) modified with a composite film of poly (4-vinylpyridine) (P4VP) and multiwalled carbon nanotubes (P4VP/MWCNT GCE) was used for the voltammetric determination of paracetamol (PCT). This novel electrode displayed a combined effect of P4VP and MWCNT on the electro-oxidation of PCT in a solution of phosphate buffer at pH 7. Hence, conducting properties of P4VP along with the remarkable physical properties of MWCNTs might have combined effects in enhancing the kinetics of PCT oxidation. The P4VP/MWCNT GCE has also demonstrated excellent electrochemical activity toward PCT oxidation compared to that with bare GCE and MWCNT GCE. The anodic peak currents of PCT on the P4VP/MWCNT GCE were about 300 fold higher than that of the non-modified electrodes. By applying differential pulse voltammetry technique under optimized experimental conditions, a good linear ratio of oxidation peak currents and concentrations of PCT over the range of 0.02–450 μM with a limit of detection of 1.69 nM were achieved. This novel electrode was stable for more than 60 days and reproducible responses were obtained at 99% of the initial current of PCT without any influence of physiologically common interferences such as ascorbic acid and uric acid. The application of this electrode to determine PCT in tablets and urine samples was proposed.