Self-Assembled Structures in Mixtures of Charged Amphiphiles and Particles

abstractcts - 9814398丹NilyU。由两亲体和固体颗粒的混合物形成的自组装结构目前被用于多种技术，如药物输送、油漆或介孔筛。然而，尽管两亲体或胶体的相行为已经被广泛研究，但我们对混合体系的理解迄今为止还不完整。本研究的目的是推导出两种一般两亲体-颗粒系统的系统相图(i)由不带电的疏水粒子与非离子两亲体形成的聚集体，以及（ii）带电胶体与相反带电两亲体的混合物。将开发相图模型，预测两亲分子特征、颗粒几何形状（球形或棒状）、颗粒大小、不同组分的浓度，以及在这种情况下系统的溶液离子强度的函数所形成的聚集体类型。两亲体的尺度和自洽场模型将与Debye Hukel或泊松-玻尔兹曼方程和蒙特卡罗静电模拟相结合。这种方法在几项初步研究中被发现是相当成功的(Dan, Biophys。J.生物物理与生物化学学报，1998,Dan and Safran，生物物理。j . 1998)。模型两亲粒子混合物的实验将与特拉华大学的E. Kaler、宾夕法尼亚大学的D. Weitz和以色列海法理工学院的Y. Talmon合作进行。这三个小组都专门研究复杂流体，特别是胶体和两亲体的相行为。所使用的技术包括电子显微镜和低温电子显微镜，小角x射线散射和小角中子散射。结合理论和实验研究将提供系统的过程控制自组装的非均质混合物，即两亲体和颗粒。这样的理解是关键的基本原理设计的新材料，可以实现特定的性能参数

ABSTRACTCTS-9814398Dan NilyU. of Delaware Self-assembled structures formed by mixtures of amphiphiles with solid particles are currently used in a variety of technologies such as drug delivery, paints or mesoporous sieves. Yet, while the phase behavior of either amphiphiles or colloids has been extensively investigated, our understanding of mixed system is, to date, incomplete.The aim of this study is to derive a systematic phase diagram of two general amphiphile-particle systems (i) Aggregates formed by uncharged, hydrophobic, particles with non-ionic ampphiphiles, and (ii) Mixtures of charged colloids wit oppositely charged amphiphiles.A model for the phase diagram will de developed which will predict the type of aggregate formed as a function of the amphiphile molecular characteristics, particle geometry (spherical or rod-like), particle size, the concentrations of the different components and, in that case systems, the solution ionic strength. Scaling and self-consistent field models for the amphiphiles will be combined with the Debye Hukel or Poisson-Boltzmann equation and Monte-Carlo simulations for the electrostatics. This approach has been found to be quite successful in several preliminary studies (Dan, Biophys. J., 1996, 1997, Biophysica et Biochimica Acta, 1998, Dan and Safran, Biophys. J. 1998).Experiments on model amphiphile-particle mixtures will be conducted in collaborations with E. Kaler of the University of Delaware, D. Weitz of the University of Pennsylvania, and Y. Talmon from the Technion, IIT in Haifa, Israel. All three groups specialize in the study of complex fluids in general, and the phase behavior of colloids and amphiphiles in particular. The techniques used include electron micrscopy and cryo-electron microscopy, small angle X-ray scattering and small angle neutron scattering.The combined theoretical and experimental studies will provide systematic understanding of the processes controlling self-assembly in heterogeneous mixtures, namely, amphiphiles and particles. Such an understanding is critical for the rationale design of new materials that can accomplish specific performance parameters