化学学报 ›› 2015, Vol. 73 ›› Issue (5): 441-449.DOI: 10.6023/A15010083 上一篇    下一篇

所属专题: 纪念南开大学化学学科创建100周年

研究论文

多金属氧簇与倍半硅氧烷簇构筑的哑铃形杂化分子Langmuir膜和Langmuir-Blodgett膜

张贝贝, 马驰, 王小刚, 胡敏标, 王晓乐, 王维   

  1. 南开大学化学学院 功能高分子材料教育部重点实验室和高分子化学研究所 合成软物质中心 天津化学化工协同创新中心 天津 300071
  • 投稿日期:2015-01-30 发布日期:2015-03-23
  • 通讯作者: 王维 E-mail:weiwang@nankai.edu.cn
  • 基金资助:

    项目受国家自然科学基金(21274069和21334003)与高分子物理与化学国家重点实验室开放研究基金资助.

Langmuir and of Langmuir-Blodgett Films of Two Dumbbell-shaped Hybrids Composed of A Polyoxometallate and Two Polyhedral Oligosilsesquioxanes

Zhang Beibei, Ma Chi, Wang Xiaogang, Hu Minbiao, Wang Xiaole, Wang Wei   

  1. Center for Synthetic Soft Materials, The Key Laboratory of Functional Polymer Materials of Ministry of Education and Institute of Polymer Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300071
  • Received:2015-01-30 Published:2015-03-23
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21274069 and 21334003) and Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry.

以两个形状杂化分子(Shape Hybrid Molecules)为目标分子, 研究了它们在气液界面上形成Langmuir膜的过程和Langmuir-Blodgett (LB)膜的聚集态结构. 杂化分子是由Wells-Dawson型磷钨氧簇(Polyoxometalates, POMs)和T8型的倍半硅氧烷簇(Polyhedral Oligosilsesquioxane, POSS), 通过对苯二甲酸有机连接链(OL)用共价键构筑的具有杂化性质和哑铃形状的簇-簇杂化分子(POM-OL-POSS). 这两种杂化分子的差别在于POSS段中, 外围有机基团的尺寸不同. 在实验中, 采用Langmuir和LB膜技术, 了解POSS外围的七个取代基变化导致的分子尺寸变化对Langmuir膜形成过程和LB膜结构的影响. 采用Langmuir技术测定了表面压-平均分子面积(π-A)等温曲线和π-A循环等温曲线, 跟踪并研究了这两个杂化分子在水表面上形成Langmuir膜的过程. 实验结果表明, 两个杂化分子都表现出良好的两亲性, 从气相变化到固相的过程中, 杂化分子经历了从分散到集中的过程. 将这些膜转移到基片上, 得到单层的LB膜, 再利用原子力显微镜(AFM)和透射电子显微镜(TEM)研究了LB膜的表面形貌和聚集态结构. 由于POM段中含有钨和钒金属, 可以直接用TEM观察聚集态结构, 发现了在气-液和液-固相转变过程中, LB膜中杂化分子的聚集态结构都呈现涨落特征, 一种凝聚态物理中由相转变导致结构涨落的重要物理现象. 本研究获得的结果能够帮助我们以及这个领域的研究者们继续优化杂化分子的结构, 进一步构筑具有有序结构的膜和本体材料.

关键词: 杂化分子, 多金属氧簇, 倍半硅氧烷簇, Langmuir膜, LB膜

In this work we report the Langmuir film-forming process and morphology of Langmuir-Blodgett (LB) films of two dumbbell-shaped hybrids at the air-water interface. The hybrids are two A-B co-cluster molecules composed of two different clusters that are covalently linked together by an organic tether. Cluster A is a trivanadium-substituted derivative of a Wells-Dawson-type tungsten polyoxometalate (POM) anion and cluster B is derivatives of polyhedral oligomeric silsesquioxane (POSS) cubic cage in which seven isobutyl or isooctyl groups attached to seven corners of the cage and an aminopropyl group attached to the eighth corner. The organic tether is a terephthalic acid. In our experiment, we used Langmuir technique to determine the surface pressure-area (π-A) isotherms and cyclic compression-expansion isotherms of the two hybrids, and then studied their Langmuir film-forming processes at the air-water interface. Our investigations show that the two hybrids can form good Langmuir films, indicating that they have good amphiphilicity. The Langmuir films have a hybrid structure: a TBA-encapsulated POM layer faced to the water surface and a POSS layer contacted with air. Meanwhile, we also used Langmuir-Blodgett (LB) technique to prepare LB film specimens for atomic force microscopy (AFM) characterization to study the surface morphology of the films and for transmission electron microscopy (TEM) characterization to study the morphology of the films. The root mean squares (RMS) of surface roughness of the LB films are smaller than 0.6 nm, only one sixth of the molecular length, meaning a smooth surface. Due to existence of tungsten and vanadium in the POM cluster, we successfully characterized the morphology of the LB films and observed a two-phase morphology in which the dark domains embedded a bright matrix. Appearance of the dark domains means formation of more ordered structures. The and size differences between the domains and matrix are intensified during the gas-liquid and liquid-solid phase transitions. This means that it is a fluctuation phenomenon of the morphology occurring in the phase transition of condensed matter. All in all, the findings provide a new method for construction of the monomolecular LB films with a hybrid structure via a rational design of hybrid molecules.

Key words: hybrids, polyoxometalates, polyhedral oligosilsesquioxanes, Langmuir films, LB films