Bronstein Lyudmila M, Sidorov Stanislav N, Zhirov Vasilii, Zhirov Denis, Kabachii Yuri A, Kochev Sergey Y, Valetsky Peter M, Stein Barry, Kiseleva Olga I, Polyakov Sergey N, Shtykova Eleonora V, Nikulina Elena V, Svergun Dmitri I, Khokhlov Alexei R
Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, USA.
J Phys Chem B. 2005 Oct 13;109(40):18786-98. doi: 10.1021/jp053333x.
The paper provides new insights into the structure of Pt-containing diblock and triblock copolymers based on poly(ethylene oxide) (PEO) and poly(4-vinylpyridine) (P4VP), using a combination of atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and anomalous small-angle X-ray scattering (ASAXS). Parallel studies using methods contributing supplemental structural information allowed us to comprehensively characterize sophisticated polymer systems during metalation and to exclude possible ambiguity of the data interpretation of each of the methods. AFM and TEM make available the determination of sizes of the micelles and of the Pt-containing micelle cores, respectively, while a combination of XRD, TEM, and ASAXS reveals Pt-nanoparticle size distributions and locations along with the structural information about the polymer matrix. In addition, for the first time, ASAXS revealed the organization of Pt-nanoparticle-filled diblock and triblock copolymers in the bulk. The nanoparticle characteristics are mainly determined by the type of block copolymer system in which they are found: larger particles (2.0-3.0 nm) are formed in triblock copolymer micelles, while smaller ones (1.5-2.5 nm) are found in diblock copolymer micelles. This can be explained by facilitated intermicellar exchange in triblock copolymer systems. For both systems, Pt nanoparticles have narrow particle size distributions as a result of a strong interaction between the nanoparticle surface and the P4VP units inside the micelle cores. The pH of the medium mainly influences the particle location rather than the particle size. A structural model of Pt-nanoparticle clustering in the diblock PEO-b-P4VP and triblock P4VP-b-PEO-b-P4VP copolymers in the bulk was constructed ab initio from the ASAXS data. This model reveals that nearly spherical micellar cores of about 10 nm in diameter (filled with Pt nanoparticles) aggregate forming slightly oblate hollow bodies with an outer diameter of about 40 nm.
本文结合原子力显微镜（AFM）、X射线衍射（XRD）、透射电子显微镜（TEM）和反常小角X射线散射（ASAXS），对基于聚环氧乙烷（PEO）和聚4-乙烯基吡啶（P4VP）的含铂二嵌段和三嵌段共聚物的结构提供了新的见解。使用能提供补充结构信息的方法进行的平行研究，使我们能够在金属化过程中全面表征复杂的聚合物体系，并排除每种方法数据解释中可能存在的模糊性。AFM和TEM分别可用于确定胶束的尺寸和含铂胶束核的尺寸，而XRD、TEM和ASAXS的结合则揭示了铂纳米颗粒的尺寸分布和位置以及有关聚合物基质的结构信息。此外，ASAXS首次揭示了本体中含铂纳米颗粒的二嵌段和三嵌段共聚物的组织情况。纳米颗粒的特性主要由其所在的嵌段共聚物体系类型决定：在三嵌段共聚物胶束中形成较大的颗粒（2.0 - 3.0 nm），而在二嵌段共聚物胶束中发现较小的颗粒（1.5 - 2.5 nm）。这可以通过三嵌段共聚物体系中胶束间交换的便利性来解释。对于这两种体系，由于纳米颗粒表面与胶束核内的P4VP单元之间的强相互作用，铂纳米颗粒具有窄的粒径分布。介质的pH值主要影响颗粒的位置而非颗粒大小。基于ASAXS数据从头构建了本体中二嵌段PEO-b-P4VP和三嵌段P4VP-b-PEO-b-P4VP共聚物中铂纳米颗粒聚集的结构模型。该模型表明，直径约10 nm的近球形胶束核（填充有铂纳米颗粒）聚集形成外径约40 nm的略呈扁球形的空心体。
