Effect of the Layer-by-Layer (LbL) Deposition Method on the Surface Morphology and Wetting Behavior of Hydrophobically Modified PEO and PAA LbL Films

Abstract

We demonstrate that the surface morphology and surface-wetting behavior of layer-by-layer (LbL) films can be controlled using different deposition methods. Multilayer films based upon hydrogen-bonding interactions between hydrophobically modified poly(ethylene oxide) (HM-PEO) and poly(acrylic acid) (PAA) have been prepared using the dip- and spin-assisted LbL methods. A three-dimensional surface structure in the dip-assisted multilayer films appeared above a critical number of layer pairs owing to the formation of micelles of HM-PEO in its aqueous dipping solution. In the case of spin-assisted HM-PEO/PAA multilayer films, no such surface morphology development was observed, regardless of the layer pair number, owing to the limited rearrangement and aggregation of HM-PEO micelles during spin deposition. The contrasting surface morphologies of the dip- and spin-assisted LbL films have a remarkable effect on the wetting behavior of water droplets. The water contact angle of the dip-assisted HM-PEO/PAA LbL films reaches a maximum at an intermediate layer pair number, coinciding with the critical number of layer pairs for surface morphology development, and then decreases rapidly as the surface structure is evolved and amplified. In contrast, spin-assisted HM-PEO/PAA LbL films yield a nearly constant water contact angle due to the surface chemical composition and roughness that is uniform independent of layer pair number. We also demonstrate that the multilayer samples prepared using both the dip- and spin-assisted LbL methods were easily peeled away from any type of substrate to yield free-standing films; spin-assisted LbL films appeared transparent, while dip-assisted LbL films were translucent.

Adhesive, Flexible, and Robust Polysaccharide Nanosheets Integrated for Tissue‐Defect Repair

“…The difference could be attributed to differences in the surface roughness; spincoating leads to low RMS roughness while dipping results in high RMS roughness in the LbL system. [26] Using a technique that results in a very weak pro-coagulant activity and that does not require an anti-coagulant agent (e.g., heparin) is a clinical advantage because postoperative embolism is due to the strong pro-coagulant activity [27] and/or the heparin-induced thrombocytopenia (HIT). [28] Therefore, one of the major problems in clinical situations can be avoided by using the polysaccharide nanosheet.…”

Tunable Layer-by-Layer Polyelectrolyte Platforms for Comparative Cell Assays

“…Moreover, the spin-assisted method results in smoother surface when compared with the dip-assisted LbL deposition method. 29 The formation of globular structures using weak electrolytes such as PAH and PAA is suppressed during the spinning process, resulting in more uniform and smoother LbL film surfaces. The pH condition was also considered at which the PAH and PAA are assembled.…”

From superhydrophilic to superhydrophobic surfaces by means of polymeric Layer-by-Layer films

“…Nevertheless, some works have recently refuted this feature and have experimentally proven the existence of exceptions that apparently contradict the rules of Layer-by-Layer method and increase roughness when the number of bilayers increase for specific materials and under certain conditions for the spray-assisted Layer-by-Layer [36] and for the classic wet approach.…”