聚苯乙烯-丙烯酸嵌段共聚物在Ca~(2 )或乙二胺存在下的自组装行为

近 1 0年来 ,人们对于具有纳米尺度聚合物自组装结构的研究日益增多 .其中 ,嵌段共聚物在选择性溶剂中的胶束行为的研究非常引人瞩目 [1～ 3] .其表现出诸多常规尺寸所不具备的特殊性能 ,使得纳米胶束不仅在理论上有研究价值 ,而且在材料化学、生物医学和环境科学等领域都具有广阔的应用前景 .Ma等[4 ] 对聚丙烯酸和聚苯乙烯接枝共聚物的研究发现聚合物接枝率和聚合物浓度以及溶液离子强度对胶束结构有影响 ;Zhang等 [1,5] 对不同嵌段比例的苯乙烯 -丙烯酸嵌段共聚物的自组装行为的研究 ,发现不同嵌段比例所对应的纳米结构不同 ;而胶束表面…     

三嵌段共聚物PAN-b-PEG-b-PAN的合成及其自组装行为的研究

利用原子转移自由基聚合(ATRP)制得了分子量可控、分子量分布窄的聚丙烯腈-b-聚乙二醇-b-聚丙烯腈P(AN-b-PEG-b-PAN)嵌段共聚物. 通过¹H NMR, FTIR, 凝胶渗透色谱(GPC)对所得产物的结构和分子量进行了表征并通过TG和DTA考察了该嵌段共聚物的热稳定性; 运用透射电子显微镜(TEM)、荧光探针技术和动态光散射(DLS)研究了P(AN)₂₇-b-P(EG)₄₅-b-P(AN)₂₇在溶剂水中胶束的形成、结构、形貌和胶束粒径. 结果表明, 三嵌段共聚物P(AN)₂₇-b-P(EG)₄₅-b-P(AN)₂₇的热稳定性较纯聚乙二醇P(EG)好, 且柔性链PEG的引入对嵌段共聚物的放热峰位置没有显著的影响. 当改变此嵌段共聚物溶液浓度时, 该嵌段共聚物会自组装成不同形状的胶束, DLS测量的胶束粒径大于TEM观察的结果, 其临界胶束浓度(cmc)约为4.46×10^－4 g•L^－1.     

聚苯乙烯-丙烯酸嵌段共聚物在不同pH值和Ca2+浓度下的胶束行为

近年来, 对具有纳米尺寸的聚合物自组装结构的研究日益增多. 其中, 嵌段共聚物在选择性溶剂中的胶束行为研究得最为广泛和深入[1~5]. 纳米胶束表现出诸多常规尺寸材料所不具备的特殊性能, 在材料化学、生物医学以及环境科学等领域有广阔的应用前景. Webber等[6]对聚丙烯酸和聚苯乙烯接枝共聚物的研究发现, 聚合物的接枝率和聚合物浓度以及溶液离子强度对胶束结构有影响; Eisenberg等[1,7]对不同嵌段比例的苯乙烯-丙烯酸嵌段共聚物的自组装行为进行研究发现, 不同嵌段比例所对应的胶束结构不同. 胶束形成的环境对胶束的形成与稳定性的影响是人们研究的重点. 本文报道了聚苯乙烯-丙烯酸嵌段共聚物在水中的胶束行为, 着重讨论了溶液pH值和钙离子浓度对聚丙烯酸链段相互作用的影响.     

聚甲基丙烯酸甲酯-聚甲基丙烯酸两亲性嵌段共聚物的制备及自组装形态的研究

以2-溴异丁酸乙酯为引发剂, 氯化亚铜/联二吡啶为催化剂, 通过原子转移自由基聚合(ATRP)获得分子链末端含一个α-溴原子的聚甲基丙烯酸甲酯(PMMA-Br), 以此为大分子引发剂引发甲基丙烯酸铅[Pb(MA)₂]单体进行ATRP反应, 制得P[MMA-b-Pb(MA)_2]嵌段共聚物, 将此共聚物在盐酸中进行离子交换即得聚甲基丙烯酸甲酯-聚甲基丙烯酸的两亲性嵌段共聚物[P(MMA-b-MAA)]. 用FTIR, GPC, NMR和SEM方法对共聚物进行了表征.     

ATRP法合成两亲性嵌段共聚物PSt-b-PAA及其在离子液体[BMIM][PF6]中的自组装行为研究

利用原子转移自由基聚合法(ATRP)合成了分子量可控、分子量分布窄的嵌段共聚物聚苯乙烯-b-聚丙烯酸叔丁酯(PSt-b-PtBA), 进而在酸性条件下由水解反应得到了两亲性嵌段共聚物聚苯乙烯-b-聚丙烯酸(PSt-b-PAA), 并通过凝胶渗透色谱(GPC)、傅立叶变换红外光谱(FTIR)、核磁共振(1H NMR)等测试手段对产物进行了表征. 使三种分子量不同的两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM][PF6])中进行自组装, 通过激光粒度分析仪(DLS)和透射电子显微镜(TEM)研究了聚合物在离子液体中自组装的胶束尺寸和结构形态. 当PSt的链段长度一定时, 胶束的形状主要依赖于PAA链的长度. 当PAA链段较长时, 胶束呈球形; 当PAA链段较短时, 则变成不规则的花生状胶束.     

两亲性嵌段共聚物的合成及其在离子液体中的自组装行为

采用阴离子开环聚合法合成了两亲性嵌段共聚物PLA-PEG-PLA.用FT-IR,1H NMR和GPC等手段对嵌段共聚物的结构组成进行了表征.两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐中能自组装成胶束,用透射电子显微镜观察了聚合物在离子液体中形成胶束的纳米结构.当疏水链长固定时,胶束的自组装形状主要依赖于亲水链的长度.两亲性共聚物在离子液体中可自组装成可控制结构的纳米胶束,这种纳米结构胶束在很多领域具有广泛的应用前景.     

光/温度双响应三嵌段共聚物的合成及溶液自组装行为

以双官能团聚乙二醇(Br-PEO-Br)为引发剂, 利用原子转移自由基聚合(ATRP)制得了含偶氮苯(AZO)和N-异丙基丙烯酰胺(NIPAM)的两亲性三嵌段共聚物P(AZO₉-co-NIPAM₉)-b-PEO₄₈-b-P(AZO₉-co-NIPAM₉), 并通过核磁共振(¹H NMR)和凝胶渗透色谱(GPC)对产物进行了表征. 该共聚物能够在溶液中自组装形成纳米胶束, 运用透射电子显微镜(TEM)、荧光探针技术和动态光散射(DLS)研究了胶束的形貌、粒径及其在光或温度刺激下的响应行为. 结果表明, 该三嵌段共聚物胶束显现出我们以往报道的二嵌段共聚物所不具有的光释放行为: 包覆有尼罗红的胶束在多次紫外-可见光循环照射之后, 荧光强度和初始状态相比下降了大约40%, 说明尼罗红在此过程中逐渐被释放. 胶束的尺寸随着温度的升高而逐渐缩小.     

两亲性ABA三嵌段共聚物的合成及其自组装行为研究

用Grubbs第二代催化剂引发降冰片烯类单体(NBEDE)和链转移剂在离子液体[bmim][BF4]中的开环易位聚合(ROMP)反应,反应体系保持均相,无聚合物析出,得到两端为叔溴的遥爪型官能化聚合物(Br-PNBEDE-Br).以Br-PNBEDE-Br作为大分子引发剂,在离子液体介质中引发甲基丙烯酸2-(二甲氨基)乙酯(DMAEMA)的原子转移自由基聚合(ATRP),制得分子量分布较窄的两亲性三嵌段共聚物(PDMAEMA-PNBEDE-PDMAEMA).利用动态激光光散射(DLS),原子力显微镜(AFM),透射电镜(TEM)等技术,考察嵌段共聚物在选择性溶剂/共溶剂(H2O/THF)中的胶束行为,以及溶液pH值对胶束的影响.结果表明,TEM观察到胶束为球形,由于TEM和AFM是在干态下测得胶束的粒径,而DLS是在溶液中测定胶束的流体力学直径,所以TEM和AFM得到的胶束粒径小于DLS的结果.不同pH值对胶束尺寸大小有明显的影响,胶束微粒随着pH值的增大而增大.     

苯乙烯-p-乙烯基苯甲酸两亲性嵌段共聚物在乙醇中自组装行为的电镜观察

两亲性嵌段共聚物在只对其中一链段为良溶剂的选择性溶剂中 ,能够自组装形成胶束 .胶束的形态和尺寸大小依赖于两链段的性质 ,共聚物的组成、浓度、溶剂的性质等[1] .这一性质使得嵌段共聚物在分子识别、药物和其他物质的输送、基因疗法、水系涂料、污染物的除去、纳米复合材料的制备、催化剂以及传感器等方面展示着潜在的应用前景 .因此 ,两亲性嵌段共聚物的合成及其在选择性溶剂中的自组装行为的研究近年来颇受关注[2 ] .依据两链段的比例不同 ,嵌段共聚物可形成星状胶束和“板寸头”(Ｃｒｅｗ ｃｕｔ)型胶束[3 ] .当可溶段远比不溶段长时…     

Solvothermal Synthesis and Characterization of （ NH3 CH2 CH2 NH3） HgSnS4 with a Column Structure

IntroductionSulfide-based open-framework materials are in-triguing compounds.They possess very diverse and in-teresting structures,and exhibit potential applicationsas a newgeneration of molecular sieves with the proper-ties of semiconductor materials[1].…     

无机-有机杂化钼磷酸盐化合物(NH3CH2CH2NH3)2Mo5O15(HPO4)2的合成与表征

0引言 钼磷酸盐由于具有丰富的晶体结构特点和化学特性使得这种材料在催化、离子交换剂和材料科学等领域有着更加广阔的应用前景[1～3].     

钒磷酸盐(NH3CH2CH2NH2)[VOPO4]的水热合成和结构表征

标题化合物是在反应物摩尔比为V₂O₅∶H₃PO₄∶H₂NCH₂CH₂NH₂∶H₂O＝0.55∶4∶3.6∶265时, 175 ℃水热反应5 d合成的. 其结构特点是: 钒八面体[VO₅N]共用角顶的氧形成“之”字型链, 链间由[PO₄]共角顶连接成层; 乙二胺分子的一个N直接与V配位, 并伸向层间. 相邻层间存在强氢键. 晶体学数据: 单斜晶系, P2₁/c (No. 14), a＝0.92108(2) nm, b＝0.72851(1) nm, c＝0.98204(2) nm, β＝101.269(7)°, V＝0.6462(4) nm³, Z＝4, D_c＝2.303 g•cm^－3, R₁＝0.0417, wR₂＝0.0999.     

(NH3CH2CH2NH3)B6O9(OH)2: Synthesis and crystal structure of a novel layered borate templated by ethylenediamine

A novel intercalated borate compound (NH₃CH₂CH₂NH₃)B₆O₉(OH)₂, has been solvothermally synthesized, and structurally characterized by single crystal X-ray diffraction. Compound crystallizes in the monoclinic, space group P2(1)/c, , , , β=93.32(3)°, , Z=4. Its oxoborate structure is built up from 1-D polyborate chains with 3, 11-membered boron rings bonded diamine molecules through electrostatic attraction and hydrogen bond interactions to construct 2-D layered compound. Other characterizations by IR, element analysis, thermal analysis and specific surface area are also discussed.     

Internal-energy-selected measurements on the relative cross section of the ion-molecule reaction NH3+(NH3, NH2)NH4+

A photoelectron-photoion coincidence technique is used to measure the internal-energy dependence of the ion-molecule reaction NH₃⁺(E_int+NH₃ → NH₄⁺ + NH₂ at thermal collision energy. The range in which the internal energy is varied, is enlarged by including in the experiment the electronically excited state of the NH₃⁺ ion. Special attention is paid to the possible influence of the product's kinetic energy on the measurements. The experimental results are analysed using a modified statistical model and compared with previous data.     

A novel organically templated three-dimensional open framework vanadium tellurite: (NH3CH2CH2NH3)2V2Te6O18

A novel organically templated vanadium tellurite (NH₃CH₂CH₂NH₃)₂V₂Te₆O₁₈ (1) has been hydrothermally synthesized and characterized by elemental analyses, IR, thermal stability analysis, magnetic susceptibilities and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P2₁/n, , , , β=94.789(4)°, , Z=2, R₁[I>2σ(I)]=0.0187, wR₂[I>2σ(I)]=0.0482. Compound 1 exhibits a novel three-dimensional (3D) vanadium tellurite anion framework composed of vanadium, tellurium, and oxygen atoms through covalent bonds, with the [NH₃CH₂CH₂NH₃]²⁺ cations residing in the channels.     

Polythermal Study of the Systems M(ClO4)2-H2O (M2+ = Mg2+, Ca2+, Sr2+, Ba2+)

The solubility polytherms in the systems for which the cryoscopic data are lacking were measured. The structural models of the electrolyte solutions were discussed on the basis of the solubility polytherms.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 413–417.Original Russian Text Copyright © 2005 by Pestova, Myund, Khripun, Prigaro.     

DSC investigation of the thermal behaviour of (NH4)2SO4, NH4HSO4 and NH4NH2SO3

Gaseous products evolved from (NH₄)₂SO₄, NH₄HSO₄ and NH₄NH₂SO₃ during successive heating and cooling cycles were flushed with inert gas into analyzer Dräger tubes hooked tightly to the terminal port of the DSC cell base. This simple procedure allowed the starting temperature of the decomposition to be determined and the amount of the individual gases in the mixture to be identified and even estimated. NH₄NH₂SO₃ at 523 K in humid air produced HNH₂SO₃ initially and, on further cycling, (NH₄)₂SO₄ and NH₄HSO₄ also appeared. The ΔH_f values for NH₄HSO₄ were (kJ mole^?1): in an airtight sample holder 12.67, in a dry argon atmosphere 11.93, and in a static air atmosphere 10.92. Endothermic peaks for (NH₄)₂SO₄ and 498 and 411 K represented the incongruent melting point and the polymorphic transition of (NH₄)₂SO₄·NH₄HSO₄. After the first heating in air to 530 K, (NH₄)₂SO₄ and NH₄HSO₄ exhibited closely similar cyclic DSC curves. The endothermic peaks at about 393–420 K may be assigned to different combinations of (NH₄)₂SO₄ and NH₄HSO₄.     

An sp2 ylide carbon-to-metal bonding: x-ray molecular structure of [PtII(NH2CH2CH2NH2)(C5H4NC(O)CNC5H3(CH3)2-3,5)]ClO4-2H2O

An X-ray structure analysis for the title complex obtained by the reaction of Pt^IICL₂(C₅H₄NC(O)C?H+NC₅H₃(CH₃)₂-3.5) with ethylenediamine in water has revealed the presence of an ylide carbon atom which is coordinated to the platinum(II) ion with an sp² configuration.