| 英文摘要 |
Fe 2 P nanorods were prepared by thermolysis using trioctylphosphine oxide (TOPO) and trioctylphosphine (TOP) as surfactants, and Fe(CO) 5 as a precursor. The nanorods and poly(2 vinylpyridine) (P2VP) were mixed to prepare nanocomposite. The behavior of nanorods in P2VP with different molecular weights was studied by the analysis of the structure of Fe 2 P/P2VP composites. The composites were preparedin both thin film and bulk architecture and were characterized by transmission electron microscopy. In composite, nanorods tend to organize into a raft-like cluster with anti-parallel particle pairs at high particleloading. Additionally, the length of rod, particle loading, molecular weight of P2VP, and the sample geometry affect the structure of clustersIn thin film, nanorods organize into a defined structure. Composite with the length of rod of 17nm forms a network structure at high particle loading and exhibits good dispersion at low particle loading. When nanorods with the length of 39nm were mixed with P2VP, they showed different arrangement in different molecular weight of P2VP, but the clusters have similar behavior of aggregation at different particle loading. As the particle content increases, the size of clusters increases. In bulk composite, the entanglement of polymer plays an important role on the arrangement of nanorods. The behavior can divided into two regimes, including M P2VP > M e and M P2VP < M e , where M e is the entanglement molecular weight. Under the condition of M P2VP > M e , polymer forms entanglement that prevents from the occurrence of large rod aggregation. As the particle content increases, the nanorods change from small sphere-like aggregates to long aggregates, and the arrangement of nanorods transfers from a random structure to a raft-like structure. At high particle loading and high molecular weight of P2VP the entropy of P2VP and the magnetization of nanorods cause the organization of nanorods to irregular aggregates. As M P2VP < M e , the polymer does not form entanglement, and the nanorods can move freely in polymer. However, huge aggregation occurs due to the magnetic force of nanorods. With an applied magnetic field, the interaction between magnetic nanorods and magnetic field force nanorods to align parallel to the magnetic field, forming a chain-like structure. As increasing the magnetitude of magnetic field, increased content of nanorods formed a chain-like structure, inducing a network structure.In nanorod/PS-b-P2VP composites, the pyridine-modified nanorods (20 nm) were sequestered into P2VP domains and aligned along the PS and P2VP. This particular orientation of nanorods was induced by theconformational entropy. As the length of nanorods increased, the aggregation of nanorods formed at low particle loading, causing a structural transition of PS-b-P2VP from lamellae to modulated lamellae. |
