Calorimetric approach to tetronic/water interactions

Tetronic^®comprises X-shaped copolymers formed by four poly(propylene oxide) (PPO) andpoly(ethylene oxide) (PEO) block chains bonded to an ethylene diamine centralgroup. Micellization behaviour of three representative Tetronics (T304, T904and T1307) was characterized to gain an insight into the interactions betweenthe copolymer unimers and the state of water in their solutions. The enthalpyof demicellization, recorded at 37°C in an isoperibol microcalorimeter,indicated that the process was in all cases exothermic and the enthalpy rankedin the order T1307≥T904>>T304. Micellization is entropy-driven owing tohydrophobic interactions between the PPO chains.DSC analysisshowed that the crystallization and melting peaks of the free water remainingin T304 and T904 solutions were progressively shifted toward lower temperaturesas the surfactant proportion increased, owing to a colligative effect. Boundwater corresponded to 3 water molecules per EO repeating unit. In the caseof T1307, which has longer PEO chains, a splitting of the melting peak wasobserved, one peak appearing around 0°C due to free water and anotherat –15°C due to interfacial water. As T1307 proportion raised, theenthalpy of the former decreased, whilst the enthalpy of the latter increased.In 40% T1307 solutions, interfacial water overcame the proportion of freewater; there being 1 interfacial and 3 bound water molecules per EO repeatingunit. Gaussian deconvolution of FTIR spectra also enabled to characterizethe evolution of free water as a function of Tetronic proportion. The dependenceof micellization and water interaction behaviour on Tetronics structure shouldbe taken into account to use these copolymers as drug solubilizers and micellarcarriers.     

Adsorption of poly(ethylene glycol)s on mercury/aqueous solution interface 1. Kinetics of PEG 8000 adsorption

In order to study the influence of the adsorption of fulvic compounds on voltammetric signals and to understand better the adsorption of these compounds on hydrophobic natural water interfaces, adsorption studies of macromolecules such as poly(ethylene glycol) (HO(CH₂CH₂O)_n) with molecular weight of 8000 were done on the mercury/water interface by a.c. voltammetry at the potential of zero charge. The maximum surface concentration, adsorption equilibrium constant and adsorption rate constant have been determined from the global adsorption mechanism, controlled by two determining steps: diffusion and kinetics of adsorption at the interface.     

铁基超细粒子催化剂结构与还原行为的Mssbauer谱研究

铁基超细粒子催化剂具有优良的F-T反应性能。本工作利用原位Mssbauer谱辅以XRD技术研究了含有钾助剂的F-T合成铁基超细粒子催化剂的结构与还原行为,考察了催化剂组成和第二金属组分(Mn,Zn,Mg)的影响。“纯”铁超细粒子催化剂在氢气中很容易经Fe_3O_4还原为零价铁。第二金属组分的引入,一方面阻碍了催化剂的还原,另一方面稳定了Fe~(2+)的存在而使其成为还原的主要中间相,这有利于反应条件下形成类尖晶石结构的活性相。对于Fe-Mn催化剂,上述效应随锰含量的增加而更趋显著。铁基超细粒子催化剂在氢气中的还原能力依“纯”Fe>Fe-Zn>Fe-Mn>Fe-Mg的顺序递减,这在一定程度上反映了铁与第二金属组分之间相互作用的强弱。     

Synthesis of monodisperse poly(chloromethylstyrene-co-divinylbenzene) beads and their application in separation of biopolymers

The monodisperse, porous poly(chloromethylstyrene-co-divinylbenzene) beads of 7.9 microm were prepared by a single-step swelling and polymerization method. The seed particles prepared by dispersion polymerization exhibited good absorption of the monomer phase. Based on this media, a weak cation-exchange (WCX) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages of biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery, and good resolution for proteins. The dynamic protein-loading capacity of the synthesized WCX packings was 18.2 mg/g. Five proteins were separated in 3.0 min using the synthesized WCX stationary phase. The experimental results show that the obtained WCX resin has very weak hydrophobicity. The WCX resin was also used for the rapid separation and purification of lysozyme from egg white in 5.0 min with only one step. The purity and specific bioactivity of the purified lysozyme were found to be more than 93% and 70 245 U/mg, respectively.     

合成1，3－二（3－羟丙基）四甲基二硅氧烷的新方法

用二乙氧基二甲基硅烷与３－氯丙醇反应，合成了新化合物３－氯丙氧基乙氧基二甲基硅烷，然后用格氏反应代替Ｗａｌｔｅｒ的钠缩合反应，最后经水解制备了１，３－二（３－羟丙基）四甲基二硅氧烷，总收率为４２．０％。     

Coordination Sorption of Urea by Novel Urea Sorbent——Polymer-bound Metal Complexes

Urea can be sorbed by coordination (or complexation)with transitional metalpolyacrylic acid complex and transitional metal-polyacrylamide containing polyethylenepolyamine ligand complexes. The experimental results indicate that the sorbents can sorb about 60mg urea per gram of sorbent at 37℃ and the concentration of urea was 1300.0rag/1 in NaH_2PO_4 and Na_2HPO_4 buffer solution (pH=7.0) and the urea sorption capacity was affected by many factors such as other competive ligands, sorption time, pH and the concentration of urea.     

石英晶体微天平技术研究纳米TiO_2表面Cu(Ⅱ)吸附与光化学还原过程

环境中排放的重金属离子Cu!对水生和陆生生物有强的毒害性。饮用水中Cu!的浓度高于1.0mg·L-1时,将会导致人畜得血色沉着病和胃肠粘膜病[1]。Cu!无法进行生物降解,除去废水中Cu!的常见方法有离子交换、置换、化学沉淀等[2],然而这些方法需要消耗大量的化学试剂,成本高。近来,研     

苯丙氨酸改性树枝状聚赖氨酸的合成及表征

以双芴甲氧羰基赖氨酸(Di- Fmoc -Lysine)为支化单元采用固相多肽合成技术制备了一种树枝状聚赖氨酸.该聚合物表面活性氨基通过与芴甲氧羰基苯丙氨酸(Fmoc- Phe)反应获得表面完全替代的苯丙氨酸改性树枝状聚赖氨酸.产物的分子量和结构经MS和NMR进行了表征.研究结果表明,利用该方法得到的产物分子量单一,是一种潜在的理想非病毒治疗载体.     

六甲氧基甲基三聚氰胺-多元醇-丙烯酸酯混杂聚合体系的研究

六甲氧基甲基三聚氰胺 (HMMM) 多元醇 丙烯酸酯 酸催化剂混杂聚合体系在高温下同时进行缩聚和自由基聚合并表现出协同效应 .体系中的活泼亚甲基在HMMM的催化下被空气氧化成过氧化氢物 ;过氧化氢物在酸催化下分解成自由基进而引发自由基聚合反应 .研究结果表明 ,体系中存在固化加速的协同效应 ;同时体系中还存在热互补效应 ,丙烯酸酯的自由基聚合反应放出的热可以传递给缩聚反应 ,满足缩聚反应吸热的要求 .混杂聚合得到的高分子合金膜具有优良的机械性能和耐溶剂性能 ,这是由于在混杂聚合过程中形成了互穿聚合物网络 (IPN)结构 .使用潜酸催化剂作为酸的来源 ,可以提高体系的储存稳定性 ;交联 引发剂的使用可以拓宽它的使用范围 ;对超枝化聚合物在混杂体系中的应用也进行了初步研究     

四（对羟基苯基）卟啉—硅胶固定相的合成及在核苷酸分析中的应用

以大孔微硅胶作基体，经γ－氨丙基三乙氧基硅烷活化与间隔臂氯代环内烷反应后，再与预先合成的四（对羟基苯基）卟啉配体键合，构成电荷转移型亲和色谱固定相。以ＰＨ＝７．０的磷酸盐缓冲溶液作流动相，成功实现对一些核苷酸的高效液相亲和色谱分离。