Polyelectrolyte Spin-Assembly

Abstract

Polyelectrolyte thin films composed of alternating layers were spin-assembled by sequentially dropping cationic and anionic aqueous solutions onto a spinning substrate. In this work, we show the applicability of our technique to multiple systems and present two methods for producing linear film growth. The polycations used were PEI (poly(ethylenimine), PDDA (poly(diallyldimethylammonium chloride), PAH (poly(allylamine hydrochloride), and two poly(propylenimine) dendrimers (generations 3.0 and 4.0). The polyanions used were PAZO (poly[1-[4-(3-carboxy-4-hydroxy-phenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt]), PSS (poly(styrenesulfonate)), and PAA (poly(acrylic acid)). Layer thicknesses for all systems were determined using single-wavelength ellipsometry. UV−vis spectroscopy was used to measure deposition amounts in films containing the chromophoric polyanions PAZO and PSS. We demonstrate the ability to spin-assemble multilayered thin films up to 50 bilayers with linear increases in deposition amount between bilayers. Additionally, we show that layers of a single polyelectrolyte species can be spin-assembled with multiple deposition cycles in which consistent amounts are deposited in each cycle. In a comparison of films built from two dendrimer generations, films incorporating generation 3.0 dendrimer and PAZO show signs of higher interpenetration between layers and a more collapsed film structure than films assembled from generation 4.0 dendrimer and PAZO. Our results also suggest that a substrate effect influences the packing density of the first few bilayers, eventually dissipating around a film thickness of 50−80 Å.

Nanostructured Crosslinkable Micropatterns by Amphiphilic Dendrimer Stamping

“…These results confirm the suitability of the spin-inking method as an alternative to dip-inking [18] to control the height and uniformity of the nanostructured and micropatterned films, and is consistent with the previously reported dependence of spincoated film thickness on concentration, spin speed, and solvent. [35,36,41] Several parameters were systematically varied to obtain high-quality patterns having smooth, intact regions of deposited ink, whose shape faithfully reproduced the topography of the stamp. Under nonoptimal conditions, undesirable pattern features were observed, including ink diffusion at the boundaries, which resulted in ragged edges, and dendrimer aggregation within inked regions, which resulted in irregularly shaped ink microdomains, separated by fissures in the case of line patterns and doughnut-shaped structures in the case of circular patterns (e.g., Figure 2a).…”

Polyelectrolyte droplets facilitate versatile layer-by-layer coating for protein loading interface

“…Recent advances in LbL assembly have been summarized by some review articles [13,14]. Spraying assembly [15,16], spin-coating [17][18][19] and patterning on the substrate [20][21][22] have already been reported. The spraying technique provides some advantages in that it skips the rinsing step and speeds up the process of building up the layers.…”

Layer‐by‐Layer Assembly (Putting Molecules to Work)

“…In a variation to the deposition by adsorption from solution, the application of layers by spraying was introduced by L. Winterton [51] and J. Schlenoff [52] and the use of spin-coaters was demonstrated by J.-D. Hong [53,54] and also by H.-L. Wang [55,56]. Both spraying and spin coating have the advantage that only small amounts of liquids are needed to coat large surface areas.…”