| He, J.; Tangirala, R.; Emrick, T.; Russell, T.P.; Böker, A.; Li, X.; Wang, J.: Self-assembly of Nanoparticle-Copolymer Mixtures: A Kinetic Point of View, Advanced Materials, 19, 381-385 (2007), doi:10.1002/adma.200602094 | |
| Abstract: Designing novel hybrid materials provides a means of controlling electrical, magnetic or optical properties. There have been numerous studies on preparing nanocomposite materials. One approach is synthesizing inorganic nanoparticles within the microdomain of a well-ordered block polymer templates. In a second approach the self-assembled microdomain morphology of block copolymers can be used to control the spatial arrangement of nanoscopic elements within the materials. The manipulation of the location of the nanoparticles in the materials can be achieved simply by controlling the sizes and the surface properties of the nanoparticles. Recent theoretical arguments suggest that synergistic interactions between self-organizing particles and a self-assembling matrix material may lead to hierarchically ordered structures. These predictions were recently confirmed in studies of a diblock copolymer having a cylindrical microdomains with added nanoparticles. In this study a co-operative, coupled interaction was found that led to hierarchically ordered structures upon thermal or solvent annealing where self-orienting, self-assembling arrays of microdomains were found without the use of external fields. However, the details of the structural evolution, and the means of manipulating the synergistic interactions, were not discussed, which is key for generalizing these concepts to different systems. To capture the detailed structural evolution of the self-assembly process in thin films of the nanoparticles/copolymer-mixtures, in-situ grazing incident small angle X-ray scattering (GISAXS) was used. Here, we report on the structure evolution in thin films of polystyrene-block-poly (2-vinylpyridine) copolymer, denoted as PS-b-P2VP, mixed with tri-n-octylphosphine oxide-(TOPO)-covered cadmium selenide (CdSe) nanoparticles. Even with the strong interfacial interactions of P2VP with the substrate, the addition of the nanoparticles to the strongly microphase-separated copolymer is seen to modify interfacial interactions and cause the microdomains to orient normal to the surface. In conjugation with our previous studies, a universality of these synergistic interactions is suggested. link to full text |
Sonderforschungsbereich 481
Komplexe Makromolekül- und Hybridsysteme in inneren und äußeren Feldern
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