Christoph Schlaich

Supramolecular polymers as surface coatings: rapid fabrication of healable superhydrophobic and slippery surfaces.

Supramolecular polymerization for non-wetting surface coatings is described. The self-assembly of low-molecular-weight gelators (LMWGs) with perfluorinated side chains can be utilized to rapidly construct superhydrophobic, as well as liquid-infused slippery surfaces within minutes. The lubricated slippery surface exhibits impressive repellency to biological li-quids, such as human serum and blood, and very fast self-healing.

Surface-Independent Hierarchical Coatings with Superamphiphobic Properties

Facile approaches for the fabrication of substrate independent superamphiphobic surfaces that can repel both water and organic liquids have been limited. The design of such super-repellent surfaces is still a major challenge of surface chemistry and physics. Herein, we describe a simple and efficient dip-coating approach for the fabrication of highly hierarchical surface coatings with superamphiphobic properties for a broad range of materials based on a mussel-inspired dendritic polymer (MI-dPG). The MI-dPG coating process provides a precise roughness control, and the construction of highly hierarchical structures was achieved either directly by pH-controlled aggregation or in combination with nanoparticles (NP). Moreover, the fabrication of coatings with a thickness and roughness gradient was possible via simple adjustment of the depth of the coating solution. Subsequent postmodification of these highly hierarchical structures with fluorinated molecules yielded a surface with superamphiphobic properties that successfully prevented the wetting of liquids with a low surface tension down to about 30 mN/m. The generated superamphiphobic coatings exhibit impressive repellency to water, surfactant containing solutions, and biological liquids, such as human serum, and are flexible on soft substrates.

Breath figure lithography for the construction of a hierarchical structure in sponges and their applications to oil/water separation

Super absorbent materials that are capable of separating oil-water mixtures have received a great deal of interest, due to their promising applications in the treatment of oil spillages and industrial discharge of oily wastewater, both of which lead to severe environmental pollution. In this paper, we describe a novel strategy for the fabrication of superhydrophobic polyurethane (PU) sponges by tailoring their structure and composition. Breath figure lithography, coupled with alkylated SiO2 nanoparticles, was used for the generation of porous nanocomposites that could be immobilised onto the PU scaffolds. The obtained PU sponges show a well-defined porous texture in the macro-, micro-, and nano-scales, and could selectively adsorb oils and/or organic solvents from water. In addition, we show that the engineered PU sponges can be magnetically driven to specific oil pollution locations by introducing magnetic nanoparticles into the PU sponges. Our approach not only demonstrates an effective method to separate oil-water mixtures but also represents an easy way to collect the separation products.

Fluorine-free superwetting systems: construction of environmentally friendly superhydrophilic, superhydrophobic, and slippery surfaces on various substrates

Surfaces that exhibit extreme wetting properties such as superhydrophobic and/or slippery liquid-infused porous surfaces (SLIPS) rely heavily on their surface energy and roughness. Although the bioaccumulation and dramatic ecological impact of perfluorinated building blocks are obvious, perfluorination of surfaces is still the most utilized method for lowering the surface energy. Herein we present a simple, substrate-independent, completely fluorine free and environmentally friendly concept for the construction of various super-wetting systems. Taking advantage of a mussel-inspired polyglycerol we successfully fabricated superhydrophilic, superhydrophobic and slippery surfaces by the precise design of a highly hierarchical structure. Additionally, the superhydrophobic coating was used to transfer commercially available cellulose and polystyrene 3D sponges into stable superhydrophobic but superoleophilic absorbent materials for oil/water separation. Moreover, the alkylated, hierarchical structure can serve as a matrix to efficiently capture hydrocarbon liquids as a lubricant that results in SLIPS. Surprisingly, common sunflower oil from the supermarket showed the same performance as pure chemicals such as hexadecane. Both the superhydrophobic and the slippery surfaces showed a similar performance regarding liquid and cell repellency in comparison to their fluorinated analog.

Bioinspired Universal Monolayer Coatings by Combining Concepts from Blood Protein Adsorption and Mussel Adhesion

Despite the increasing need for universal polymer coating strategies, only a few approaches have been successfully developed, and most of them are suffering from color, high thickness, or high roughness. In this paper, we present for the first time a universal monolayer coating that is only a few nanometers thick and independent of the composition, size, shape, and structure of the substrate. The coating is based on a bioinspired synthetic amphiphilic block copolymer that combines two concepts from blood protein adsorption and mussel adhesion. This polymer can be rapidly tethered on various substrates including both planar surfaces and nanosystems with high grafting density. The resulting monolayer coatings are, on the one hand, inert to the adsorption of multiple polymer layers and prevent biofouling. On the other hand, they are chemically active for secondary functionalization and provide a new platform for selective material surface modification.

Mussel-Inspired Polyglycerol Coatings with Controlled Wettability: From Superhydrophilic to Superhydrophobic Surface Coatings

Facile approaches to substrate-independent surface coatings with special wettability properties, such as superhydrophobicity, superhydrophilicity, and superamphiphobicity, have been limited. To address this problem, we combined two separate biomimetic concepts of mussel-inspired adhesion and highly hierarchical lotuslike surface structures to develop a universal fabrication method for various superwetting systems on any kind of material. In this feature article, we summarize our work on mussel-inspired polyglycerol (MI-dPG) and its application in the area of superwetting interfacial materials. MI-dPG mimics not only the functional groups of mfp-5 but also their molecular weight and molecular structure, which results in strong and rapid adhesion to the substrate. Furthermore, the MI-dPG coating process provides precise roughness control. The construction of highly hierarchical and superhydrophilic structures was achieved either directly by pH-controlled aggregation or in combination with nanoparticles. Subsequent postmodification of these highly hierarchical structures with different fluorinated or nonfluorinated hydrophobic molecules yielded a surface with superhydrophobic and even superamphiphobic properties.

Photoregulating Antifouling and Bioadhesion Functional Coating Surface Based on Spiropyran

Dynamic regulation of the interactions between specific molecules on functional surfaces and biomolecules, for example, proteins or cells, is critical for biosensor and biomedical devices. Herein, we present a spiropyran (SP)-based light-responsive surface coating, hPG (hyperbranched polyglycerol)-SP, to control the adsorption of proteins and adhesion of cells. In the normal state, the SP groups on the coating surface were in hydrophobic ring-closed form, which promotes the nonspecific protein adsorption and cell adhesion. Under UV irradiation, the grafted SP groups were dynamically isomerized into hydrophilic/zwitterionic merocyanine. Both hydrophilicity and zwitterions support the formation of a hydrated layer and hence the resulting hPG-MC coatings highly resist protein adsorption and cell adhesion. Moreover, the presented hPG also provided a robust bioinert background to suppress the nonspecific protein adsorption and cells adhesion. Therefore, this functionalized coating exhibited a good photoregulated antifouling behavior. Moreover, the detachment of adsorbed proteins and adhered cells from the coating surface was also realized.