Co-assembly of block copolymers and nanorods in ultrathin films: effects of copolymer size and nanorod filling fractionElectronic supplementary information (ESI) available: SEM images of composite films consisting of the short copolymer after prolonged annealing in chlorofom under reduced vapour pressure (Fig. S1). See DOI: 10.1039/c0cp00277a

• Main Authors: Ploshnik, Elina, Salant, Asaf, Banin, Uri, Shenhar, Roy
• Format: Journal Article
• Language: English
• Published: 23.09.2010
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c0cp00277a

Two-dimensional, hierarchical assemblies of nanorods were obtained by exploiting the structures afforded by block copolymers in ultrathin films. Under the appropriate conditions, the nanorods segregate to the film surface already upon casting the composite film, and organize with the block copolymer through phase separation. In this paper we compare the structures formed by CdSe nanorods of three different lengths and two polystyrene- block -poly(methyl methacrylate) copolymers with different nanorods/copolymer ratios, and study the temporal evolution of the structure in each case. It is found that the initial morphology of the film largely dictates the resulting structure. The combination of short nanorods and/or short copolymers is shown to be more prone to morphological defects, while assembling long nanorods with long copolymers leads to highly organized nanorod morphologies. These phenomena are explained by a combination of kinetic and thermodynamic factors. Exploration of the cooperative self-assembly process of CdSe nanorods and block copolymers in ultrathin films gives insights into the kinetic and thermodynamic factors governing this process.