Fabrication of a Superhydrophobic Surface from the Amplified Exponential Growth of a Multilayer

Abstract

Superhydrophobic surfaces have received much attention due to their novel aspects of surface physics and important applications ranging from self-cleaning materials to microfluidic devices. Taking their inspiration from the self-cleaning property of lotus leaves [1] and insects, [2] the biomimetic results reveal that the synergistic interaction of the hierarchical micro-and nanostructure can not only improve the surface hydrophobicity but also reduce the sliding angle (SA), which is crucial to the self-cleaning properties of these surfaces.[3] Many efforts, including electrodeposition, polymer-phase separation, sol-gel methods, and others have been carried out to develop hierarchical micro-and nanostructures to obtain superhydrophobic surfaces. [4][5][6] Layer-by-layer self-assembly (LbL), which is based on the alternating physisorption of oppositely charged building blocks, represents a method to immobilize polyelectrolytes, colloid nanoparticles, and biomacromolecules, such as enzymes, extracellular matrices (ECM), DNA, etc. [7][8] The sensitivity of the LbL multilayer towards its environment (pH, ionic strength, etc.) further provides new approaches to adjust the layered nanostructure with a tailored composition and architecture. Recently, the use of the LbL technique for constructing superhydrophobic coatings has been explored. [9][10][11][12] Shiratori and co-workers [9] first constructed multilayered films containing SiO 2 nanoparticles, which were further heated to 650°C to develop an inorganic nanostructure for superhydrophobic behavior. Zhang and co-workers [10] reported the use of polyelectrolyte multilayers as a matrix for electrochemical deposition to adjust the topography of gold and silver clusters, leading to superhydrophobic surfaces. Rubner and co-workers [11] mimicked the superhydrophobic behavior of the lotusleaf structure by creating a microporous polyelectrolyte multilayer surface over-coated with silica nanoparticles. Schlenoff and co-workers [12] created an ultrahydrophobic surface roughening on both the micrometer and nanometer scale using layer-by-layer deposition of clay and fluorinated polyelectrolytes. Most of these methods, however, developed hierarchical micro-and nanostructures by combining the multiple assembly steps and different self-assembling building blocks, such as polyelectrolytes, metals, and nanoparticles. Herein, we report the amplified exponential growth of a multilayer of polyelectrolytes as a facile method to construct hierarchical micro-and nanostructures simultaneously, which can be further transformed into superhydropobic surfaces. The 3-aminopropyltriethoxysilane-coated substrates were alternately immersed in an aqueous solution of poly(acrylic acid) (PAA, 3 mg mL -1

Preparation and monovalent selective properties of multilayer polyelectrolyte modified cation‐exchange membranes

“…It seems that the initial three polyelectrolyte layers on the CEM were thicker than the subsequent layers. This is not in accordance with early studies 29,30 that the PEI/PAA multilayer films grow exponentially in the first several bilayers. We believe it was mainly due to the different substrates for polyelectrolyte adsorption.…”

Multiple Functionalities of Polyelectrolyte Multilayer Films: New Biomedical Applications

“…[39] In addition, the growth can be amplified by pH leading to even thicker films obtained in a very limited number of depositing cycles. [40] Better understanding of the different growth mechanisms is also emerging. [12] For instance, Porcel et al [41] showed that a transition from exponential to linear growth occurs at a certain level in film buildup.…”

“…[221] Superhydrophobic surfaces also attract lots of attention and are inspired by the natural designs of the Lotus leaf or insect wings. Ji et al [40] prepared superhydrophobic films using films that grow exponentially with growth that was amplified due to the presence of silver ions. Other strategies rely on organic-inorganic hybrid films, such as PAH and ZrO 2 nanoparticle coatings, [222] in combination with the LbL technique with electrochemical depositing of dendritic gold aggregate coatings on gold threads, [223] or on a polyelectrolyte/sodium silicate combination.…”

Interaction of Zoospores of the Green Alga Ulva with Bioinspired Micro‐ and Nanostructured Surfaces Prepared by Polyelectrolyte Layer‐by‐Layer Self‐Assembly

“…[51][52][53][54] In the work reported here, polyelectrolyte multilayers (PEMs) with hierarchical nano-and microscale surface structures were constructed of poly(acrylic acid) (PAA) and polyethyleneimine (PEI), [12] which show an exponential growth mode. [55,56] To speed up preparation and to move towards future practical application, spray coating was used for the layer-by-layer application. [57,58] The pH of the applied polyelectrolyte solutions was tuned to obtain morphologies with systematically varying structure sizes.…”