A series of gold precursor solutions are prepared by dissolving HAuCl4 and its mixtures with K2CO3 of different contents in deionized (DI) water. Neat HAuCl4 predominately forms AuCl4 – ions in an aqueous solution. In the presence of K2CO3, AuCl4 – ions hydrolyze to form [AuCl4–x (OH) x ]− complex ions. Increasing the content of K2CO3 in a gold precursor solution increases the content of [AuCl4–x (OH) x ]− complex ions and decreases the content of AuCl4 – ions. Poly­(4-vinyl pyridine) (P4VP) films of two different molecular weights are deposited on SiO x /Si by spin coating, by which the thicknesses are controlled by polymer weight fractions in butanol. Those P4VP films form periodic wrinkles when immersed in aqueous solutions, followed by drying. The surface wrinkling is induced by swelling pressure that overwhelms the mechanical property of the P4VP film. The periodicity and amplitude of wrinkles grown on the P4VP films strongly correlate with initial thickness, AuCl4 – ion content, and residual stress.

We have demonstrated the phase behavior of substrate-supported films of a symmetric weakly-segregated polystyrene-block-poly (methyl methacrylate), P(S-b-MMA), block copolymer and its blends with a homopolymer polystyrene (PS) at different compositions....

We have demonstrated the effects of different chain lengths on the phase behavior in films of binary blends of four different weight fractions in a weak segregation limit. The binary blends were composed of nearly symmetric polystyrene-block-poly(methyl methacrylate), PS-b-PMMA, and homo-polystyrenes (PS) of three different molecular weights (hereafter hPS 2.8 , hPS 6 , and hPS 17 ). Films of two initial thicknesses were prepared by spin coating of the blends. After thermal annealing at 270 °C (1 h), a series of nanodomains, including perforated layers, double gyroid, cylinders, and spheres, were obtained in sequence as the volume fractions of PS increased in blend films. Perforated layers and double gyroid only exist in PS-b-PMMA-rich blend films, with hPS 2.8 /PS-b-PMMA blends overwhelmingly favoring perforated layers, regardless of film thickness. However, with a small amount of hPS 6 chains, PS-b-PMMA-rich blends preferentially form hexagonally perforated layers in thin films but double gyroid in thick films; at the same composition, PS-b-PMMA-rich blends with hPS 17 chains only form hexagonally perforated layers. Cylinders only formed in blend films of equal weight fractions of PS-b-PMMA and PS. The cylinders with hPS 2.8 and hPS 6 chains favor parallel orientation, but cylinders with hPS 17 PS chains favor a mixed orientation. Spheres predominantly formed in PS-rich blend films, where four types of domain ordering (hexagonal packing, body-centered cubic (BCC), face-centered cubic (FCC), and short-range order) were obtained. For blend films prepared in the PS-rich regions, the four types of ordering depend on chain length and film thickness. The PS-b-PMMA blend films with hPS 2.8 chains predominantly favor hexagonal packing of spheres for thin films but BCC packing of spheres for thick films. Under the same PS-rich region, the PS-b-PMMA blend films with hPS 6 chains predominantly favor hexagonal arrays of spheres in thin films but FCC-packed arrays of spheres in thick films. The PS-b-PMMA blend films with hPS 17 chains predominantly favor short-rangeorder spheres or a mixture of spheres and cylinders with no lattice packing. All of the above findings are explained by the correlation between the variations in chain length and alleviating packing frustration.

Poly(2-vinyl pyridine), P2VP, films display a surface pattern of craters in a dried state after being immersed in aqueous solutions containing HAuCl4 and its mixtures with low contents of K2CO3. The morphologies of craters indicate that the formation of craters involves three stages through film blistering and drying: (i) the permeability of water and solutes to swell P2VP films, (ii) partial wetting of liquid droplets near the substrate interface in the presence of the P2VP film, and (iii) evaporation-driven flows. The three stages produce the swelling pressure, Laplace pressure, and interplays among capillary flows, Marangoni flows, and pinning effects, respectively, by which craters of different dimensions and morphologies are obtained. The first stage softens the P2VP films and produces swelling pressure. This stage relies on interactions between AuCl4 – ions, water, and protonated P2VP chains. The second stage produces liquid droplets inside the film and near the substrate interface. The surface tensions of those liquid droplets at contact lines deform swollen P2VP films. Changing film thicknesses or substrate types alters craters’ lateral dimension and depth. The results indicate that film thicknesses and substrate interface energies influence the shape and dimension of liquid droplets on the substrate interface. The third stage determines morphologies of craters through interplays among capillary flows, Marangoni flows, and pinning/depinning events.