The PVP cakes inside could compress the surrounding cakes to pursue an equilibrium of interfacial tension, which lies
in the size of PVP cakes, exhibiting a perpendicular plane among the cakes. More quantitatively, solid laterals or arc laterals among the patterning could be observed from top and side view. Due to lack of adequate surrounding cakes, the cakes outside could penetrate find more into the bottom of the ones inside, exhibiting an arc lateral from side view, and/or two crossed arcs from top view. On the basis of our previous studies [11, 22], interfacial polygonal patterning could be tuned by manipulating surfactant population, concentration of metallic nanoparticles, amount and type of PVP in 2-propanol, process temperature and time, etc. Herein, the surfactant population is manipulated with modified modes at different stages: synthesis of AuNPs (pristine anchored DDTs) and solvothermal treatment of AuNPs (freshly supplementary DDTs). For instance, Au seeds (Au/DDT=0.1) was mixed 17DMAG with freshly prepared DDT (0.11 M, 22 mL) and PVP (1.25 mM, 0.5 mL), followed by solvothermal treatment (180°C and 4 h). The resultant products are
presented in Figure 3a,b, exhibiting apparent and close-packed interfacial polygonal patterning. When anchored DDT on Au seeds is decreased, the voids (pointed out by white arrow in Figure 3c) appear to form loose-packed cakes. Under identical conditions, 2 mL of fresh DDT (isolated DDT molecules, Figure 2b) was added in, leading to charcoal-drawing patterning with snatch laterals. Surprisingly, in the interconnection zones among three cakes are very sparsely distributed AuNPs, pointed out by dotted circle (Figure 3f). Very few voids also could be observed in Figure 3e. As
noted earlier, the generation of interior porosity is apparently associated with the depletion of anchored surfactants and direct attachment among the AuNPs. Figure 3 TEM images. Typical interfacial polygonal patterning – experimental conditions: AuNPs (2STU) + DDT (0.11 M) + PVP (1.25 mM), 180°C, 4 h. (a, b) Au/DDT = 0.1, DDT (22 Etoposide mouse mL); (c, d) Au/DDT = 0.2, DDT (22 mL); (e, f) Au/DDT = 0.1, DDT (22 mL); See Entospletinib Additional file 1: SI-1 for more information on their detailed experimental conditions. To further confirm the synergistic effect of PVP and DDT, the effects of stand-alone surfactant-mediated self-assembled nanostructures are carried out first (see Additional file 1: SI-2). Besides PVP in-2 propanol solvent (without any addition of fresh DDT), solid PVP powders were also used to tailor self-assembly of AuNPs. Meanwhile, various amounts of freshly prepared DDT were applied to fine tune the gold nanostructures. Nevertheless, the morphology yields for resultant products as gold sponges are extremely high at about 100% instead of interfacial polygonal patterning.