Fig. 4.
Examples of aggregates whose sizes were controlled by the times of UV irradiation. (A) The smallest ordered structures formed at high CADT ([ADT] = 0.12 mM; 1:4 v/v methanol/toluene) and were made of only a few cross-linked NPs. Upon further irradiation, more free NPs attached to such growing “nuclei” to give ordered structures composed of hundreds (B and C) to millions (D) of NPs. The assemblies in (A–C) were all soluble; large crystals like the one in D precipitated from solution. (Scale bars: A, 5 nm; B, 20 nm; C, 50 nm; D, 200 nm.)