Patterned and Controlled Polyelectrolyte Fractal Growth and Aggregations

Abstract

Two-dimensional patterned and controlled polyelectrolyte aggregations (e.g., tree-like ramified structures) created by microcontact printing have been demonstrated and discussed. Polyelectrolyte-micropatterned aggregations on surfaces were controlled by the micropattern size and shape of PDMS stamps. The formation of aggregates was dependent on the ink and surface conditions, and the aggregates consisted of two distinct layers; strongly adsorbed, primary uniform layers and weakly adsorbed, secondary aggregation layers positioned on top of the primary layers. The adsorption of the primary layers was strong enough not to be washed away, while the aggregated secondary layers were easily removed by washing. The aggregation of secondary layers showed typical tree-like ramified structures of fractal growth and aggregation. Directional and confined stamping led to directing and confining the growth of the fractal polyelectrolyte clusters, respectively. The micropatterned primary uniform layers were not removed by extensive washing, and they were identified by selective nickel plating and charged particle selective adsorption in which the surface formed positive and negative micropatterns. These functional and patterned surfaces have great potentials for advanced devices and sensors.

Nanostructured Crosslinkable Micropatterns by Amphiphilic Dendrimer Stamping

“…However, mechanisms involved in polyelectrolyte aggregation under similar conditions have been explained elsewhere. [28] While aggregation could be eliminated by increasing the dendrimer concentration and contact time, at very high concentrations and contact times, diffusion also became a problem.…”

“…These techniques have been used to make patterns of various small and large molecules on metals and silicon substrates [19][20][21] as well as to deposit proteins, biological cells, [22][23][24] polymer thin films (POPS), [25] controlled particle cluster arrays [26] and their selective metal plating, [27] and polyelectrolyte aggregates. [28] Microcontact printing of PAMAM dendrimers has recently been reported. [29][30][31][32][33][34] In these studies, the effect of dendrimer concentration on the pattern thickness was evaluated, and new approaches for electroless metallization of these patterns were suggested.…”

Arrays of lipid bilayers and liposomes on patterned polyelectrolyte templates

“…Microcontact printing offers advantages over conventional photolithographic techniques because it is simple to perform and is not diffraction-limited. This technique has been used to make patterns of various small and large molecules on metals and silicon substrates [59][60][61][62], as well as to deposit proteins [63] and polyelectrolyte aggregates [64]. POPS is an approach that combines LBL assembly and µCP to generate alternating regions of different chemical functionalities on a surface by using graft, diblock copolymers or polyelectrolytes as ink [51,52].…”

Dye deposition patterns obtained in line printing on macroporous membranes: Improvement of line sharpness by liquid redistribution

“…In principle, such a mechanism can lead to fractal deposition patterns, which have been reported for other types of printing processes [28][29][30]. Fractal patterns obtained by imprinting are also well known from the Rorschach blots [31].…”