GOALI: Generation, Characterization, and Modeling of Structure and Properties of Polymer Blend Nano- and Microparticles

9982077Otaigbe这一目标奖，由分部共同支持。材料研究部和数学和物理科学局多学科活动办公室是纳米科学领域的合作伙伴。当聚合物被限制在分子大小的小液滴或分子聚集体中时，就会出现新的动力学行为。溶剂挥发在足够短的时间尺度上进行，足以阻碍相分离，产生在分子尺寸内均一的干燥纯聚合物或聚合物混合微粒。这种能力使得只需调整聚合物在溶液中的相对重量分数，就可以生产具有可调性能(如折射率)的球形聚合物合金微粒。这项研究将开发一种方法来产生聚合物和聚合物混合微粒子，并探测聚合物微粒子和纳米粒子的结构、形态和其他特征。使用为探测亚微米液滴中的单个荧光分子而开发的仪器，该提案将证明，可以通过窄尺寸分散来制备几乎任意大小和组成的聚合物颗粒。虽然这项研究的重点是聚合物系统，但微粒子发生器可以很容易地改装成小的有机和无机粒子(以及混合系统)。许多光学方法，如夫琅和费衍射，荧光和传统的相差显微镜将被用来探测固定在二维衬底上的聚合物颗粒，或使用三维四极(Paul)陷阱悬浮在空间中的聚合物颗粒。光学衍射法将在几毫秒的测量时间内提供聚合物颗粒内部的独特外观(目前电子束显微镜等传统方法无法实现)，使其对在线生产应用具有吸引力。所获得的知识将有助于解决相分离问题，相分离是从溶液中的本体不相容组分生产许多具有技术意义和科学意义的均质聚合物混合物的主要障碍。聚合物微粒的应用领域的例子包括聚合物混合物或合金、用于药物输送系统的生物材料、电光和发光器件、聚合物粉末喷涂、以及无机纤维在复合材料和聚合物支撑的多相催化中的聚合物粉末浸渍。

9982077OtaigbeThis GOALI award, jointly supported by the Div. of Materials Research and the Office of Multidisciplinary Activities of the Directorate for Mathematical and Physical Sciences, is in the area of nanoscience. New dynamic behavior emerges when polymers are confined in a small droplet of solution the size of a molecule or in molecular aggregates. Solvent evaporation takes place on a time scale short enough to frustrate phase separation, producing dry pure polymer or polymer blend microparticles that are homogeneous within molecular dimensions. This capability allows production of spherical polymer alloy microparticles with tunable properties (such as refractive index) simply by adjusting the relative weight fractions of the polymers in solution. This research will develop a methodology for generating polymer and polymer blend microparticles and for probing the structure, morphology, and other characteristics of the polymer micro- and nanoparticles. Using instrumentation developed for probing single fluorescent molecules in submicrometer droplets, the proposal will demonstrate that polymer particles of nearly arbitrary size and composition can be made with narrow size dispersion. While the focus of this research is on polymeric systems, the microparticle generator can be easily adapted to make small organic and inorganic particles (and hybrid systems). A number of optical methodologies such as Fraunhofer diffraction, fluorescence, and conventional phase-contrast microscopy will be used to probe polymer particles immobilized on two-dimensional subrstrates or levitated in space using a three-dimensional quadrupole (Paul) trap. The optical diffraction method will provide a unique look (not possible now with conventional methods such as electron-beam microscopy) inside a polymer particle in a measurement time schale of a few milliseconds, making it attractive to in-line production applications.The knowledge gained will be useful in addressing phase separation, the primary barrier to producing many technologically relevant and scientifically interesting homogeneous polymer blends from bulk-immiscible components in solution. Examples of application areas of the polymer microparticles include polymer blends or alloys, biomaterials for drug delivery systems, electro-optic and luminescent devices, polymer powder spray coating, and polymer powder impregnation of inorganic fibers in composites and in polymer-supported heterogeneous catalysis.