Self-assembly processes: general discussion Javier Reguera, Christophe Petit, Leonardo Scarabelli, Xiaoying Liu, Edward Malachosky, Matthew Martin, Bruce Law, Xiao-Min Lin, Helmuth Moehwald, Peter Schurtenberger, Heiko Wolf, Vicki Meli, Damien Faivre, Eser Metin Akinoglu, Dhanavel Ganeshan, Fernando Bresme, Yangwei Liu, Casper Kunstmann-Olsen, Christopher Sorensen, Suvojit Ghosh, Asanka Yapa, Asaph Widmer- Cooper, M. Fernanda Cardinal, Almudena Gallego, Ozgur Tarhan, Gunadhor Okram, Andreas Fery, Emanuela Del Gado, Lucio Isa, R ´ egine Perzynski and Brian Korgel DOI: 10.1039/c5fd90043c Bruce Law opened a general discussion of the paper by Brian Korgel: You use grazing incidence SAXS (GISAXS) to detect the presence/absence of the nano- crystal superlattice structure. Are you detecting the bulk or surface-induced superlattice structure? Can you tell the difference? How would the bulk/surface structure change the GISAXS pattern? Brian Korgel answered: GISAXS is an excellent tool for examining the structure of thin lms, even as thin as a monolayer. The patterns reveal whether there is a preferential superlattice orientation on the substrate and this is easy to discern by indexing. Usually, there is a preferred superlattice crystal plane that assembles on the substrate. In this paper, the lms are relatively thick – we tend to consider them as bulk lms – but there is a preferential superlattice orientation on the substrate. In some systems (not the one here though) there can be a shrinking of the lattice towards the substrate – that is a fairly common effect that has been observed in nanocrystal superlattice lms. Bruce Law asked: Your Fig. 1 (and Fig. 5) exhibit increased (and decreased) nanocrystal superlattice order at higher temperatures for a sample possessing a polydispersity of 18.3% (20%). There is not much difference between 18.3% and 20%. I am surprised that such a small difference in polydispersity can make such a large difference. It seems that the dening characteristic is whether or not order is present (Fig. 1c) or absent (Fig. 5b) at low temperatures. Perhaps this effect is more due to the history or kinetics of a particular sample rather than due to the polydispersity; namely, has order been induced in a particular sample e.g. by nucleation or use of a “seed”? This journal is © The Royal Society of Chemistry 2015 Faraday Discuss. Faraday Discussions Cite this: DOI: 10.1039/c5fd90043c DISCUSSIONS Published on 07 July 2015. Downloaded on 11/07/2015 00:36:48. View Article Online View Journal