Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

Oil spills and industrial organic pollutants have induced severe water pollution and threatened every species in the ecological system. To deal with oily water, special wettability stimulated materials have been developed over the past decade to separate oil-and-water mixtures. Basically, synergy between the surface chemical composition and surface topography are commonly known as the key factors to realize the opposite wettability to oils and water and dominate the selective wetting or absorption of oils/water. In this review, we mainly focus on the development of materials with either super-lyophobicity or super-lyophilicity properties in oil/water separation applications where they can be classified into four kinds as follows (in terms of the surface wettability of water and oils): (i) superhydrophobic and superoleophilic materials, (ii) superhydrophilic and under water superoleophobic materials, (iii) superhydrophilic and superoleophobic materials, and (iv) smart oil/water separation materials with switchable wettability. These materials have already been applied to the separation of oil-and-water mixtures: from simple oil/water layered mixtures to oil/water emulsions (including oil-in-water emulsions and water-in-oil emulsions), and from non-intelligent materials to intelligent materials. Moreover, they also exhibit high absorption capacity or separation efficiency and selectivity, simple and fast separation/absorption ability, excellent recyclability, economical efficiency and outstanding durability under harsh conditions. Then, related theories are proposed to understand the physical mechanisms that occur during the oil/water separation process. Finally, some challenges and promising breakthroughs in this field are also discussed. It is expected that special wettability stimulated oil/water separation materials can achieve industrial scale production and be put into use for oil spills and industrial oily wastewater treatment in the near future.

Biomimetic super-lyophobic and super-lyophilic materials applied for oil/water separation: a new strategy beyond nature

Studying nature to reveal the mechanisms of special wetting phenomena in biological systems can effectively inspire the design and fabrication of functional interfacial materials with superwettability. In this Review, the historical development, new phenomena and emerging applications of superwettability systems are discussed.

Nature-inspired superwettability systems

Polydopamine is one of the simplest and most versatile approaches to functionalizing material surfaces, having been inspired by the adhesive nature of catechols and amines in mussel adhesive proteins. Since its first report in 2007, a decade of studies on polydopamine molecular structure, deposition conditions, and physicochemical properties have ensued. During this time, potential uses of polydopamine coatings have expanded in many unforeseen directions, seemingly only limited by the creativity of researchers seeking simple solutions to manipulating surface chemistry. In this review, we describe the current state of the art in polydopamine coating methods, describe efforts underway to uncover and tailor the complex structure and chemical properties of polydopamine, and identify emerging trends and needs in polydopamine research, including the use of dopamine analogs, nitrogen-free polyphenolic precursors, and improvement of coating mechanical properties.

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Polydopamine Surface Chemistry: A Decade of Discovery.

The separation of oil from oily water is an important pursuit because of increasing worldwide oil pollution. Separation by the use of materials with selective oil/water absorption is a relatively recent area of development, yet highly promising. Owing to their selective superantiwetting/superwetting properties towards water and oil, superhydrophobic/superoleophilic surfaces and underwater superoleophobic surfaces have been developed for the separation of oil/water-free mixtures and emulsions. In this Review, after a short introduction to oil/water separation, we describe the principles of materials with selective oil/water absorption and outline recent advances in oil/water separation with superwetting/superantiwetting materials, including their design, their fabrication, and models of experimental setups. Finally, we discuss the current state of this new field and point out the remaining problems and future challenges.

Oil/Water Separation with Selective Superantiwetting/Superwetting Surface Materials

The invention discloses a magnetic demulsifier capable of being controllably recovered aiming at a water-in-oil system emulsion and a preparation method thereof. The preparation method of the demulsifier comprises the following steps: (1) adding magnetic powder to deionized water, and carrying out ultrasonic treatment to form turbid liquid; (2) adding a sodium silicate solution to the turbid liquid, and carrying out heating treatment on the overall system; (3) recovering solid in the turbid liquid in the step (2) by using a magnet, and baking; (4) soaking the solid dried in the step (3) into a silane coupling agent or a solution of the silane coupling agent, recovering the solid by using a magnet, and then baking after washing, so as to obtain the demulsifier. By adopting the demulsifier provided by the invention, the demulsifying process aiming at the water-in-oil system emulsion can be quickly and efficiently achieved, the demulsifier can be completely recovered by using a magnetic field, and can be repeatedly used by a simple cleaning process, the demulsifying efficiency is stable after multi-time repeating, and the demulsifier can be applied to the demulsifying process of the water-in-oil system emulsion.

High-efficiency magnetic demulsifier capable of being controllably recovered aiming at water-in-oil system emulsion and preparation method thereof

The invention discloses a solution response oil and water separation net membrane based on electrostatic self-assembly, a preparation method and applications. The preparation method comprises the following steps: first, water is added into polymer monomers, cross-linking agents, initiators and thickening agents and mixed, and a prepolymerization solution is obtained; second, the prepolymerization solution is painted on a surface of a fabric net plated with metal, then crosslinking polymerization of the prepolymerization solution is carried out, a fabric net coated with hydrogel is obtained, and the fabric net is a stainless steel net, a copper fiber fabric net, an iron fiber fabric net or an aluminum fiber fabric net; third, the fabric net coated with hydrogel is dipped in an ethanol solution of eleaostearic acid, and a solution response oil and water separation net membrane is obtained. The raw materials are easily available, the suitable raw material scope is wide, the raw material universality is good, the separation efficiency is high, the solution response oil and water separation net membrane can be suitable for oil and water separation under a plurality of conditions, large scale production application can be carried out, the preparation processes are simple and practical, the flux is large, and the stability is good.

Solution response oil and water separation net membrane based on electrostatic self-assembly, preparation method and applications

We present a re-usable enzyme catalyst system via direct encapsulation of cellobiase in nonsurfactant templated sol–gel mesoporous silica host material with d-fructose as the template. The pore diameter and porosity of the silica host material, controlled by the fructose content, controlled the diffusion of substrate to the enzyme. This in situ immobilized cellobiase showed little or no leakage while could be repeatedly used as biocatalyst with little or no loss of activity after at least 9 cycles.

http://www.pages.drexel.edu/~hj56/PDFfiles/2012/top%20catal.pdf

Synthesis of a Re-usable Cellobiase Enzyme Catalyst through In situ Encapsulation in Nonsurfactant Templated Sol–Gel Mesoporous Silica

Effective purification of waste water tainted with either immiscible oil/water mixtures or surfactant-stabilized emulsions is always attractive for long-term water remediation. We report here on a versatile development of polydopamine coated copper surfaces on various porous substrates via a simple one-step immersing method. The incorporation of dopamine into this design not only optimizes the operation of preparing simple substances on copper surfaces on a wide range of substrates, but also endows the as-obtained membranes with superhydrophilicity and underwater superoleophobicity. Such membranes are capable of efficiently separating both immiscible oil/water mixtures and surfactant-stabilized emulsions based on the desired substrates, and they display superior chemical resistance to aggressive reagents, excellent recyclability and robust structural stability, making them promising candidates for a variety of oil filtration applications ranging from the treatment of oil/water mixtures to emulsified oily waste water.

One-step reduction and simultaneous decoration on various porous substrates: toward oil filtration from water

The invention discloses a bionic robot fish propelled by swinging of flexible pectoral fins driven by artificial muscles. The bionic robot fish comprises a robot fish body, flexible pectoral fins, a fish tail, a controller and a flexible waterproof sleeve, wherein the flexible pectoral fins adopt a laminar flexible structure and manner of flexible driving of electrically-active polymerized substance artificial muscles, and consist of a plurality of flexible driving units; each of the driving units can be independently controlled, and a complex fin surface waveform and complex fin surface movement can be realized. The bionic robot fish disclosed by the invention has the advantages that the flexible driving and the flexible structure can be realized through the function that the movement of fish is propelled by simulating the swinging of the pectoral fins, and the controllable complex fin surface shape is realized.

Yingze Cao

Papers

High-efficiency magnetic demulsifier capable of being controllably recovered aiming at water-in-oil system emulsion and preparation method thereof

Solution response oil and water separation net membrane based on electrostatic self-assembly, preparation method and applications

Synthesis of a Re-usable Cellobiase Enzyme Catalyst through In situ Encapsulation in Nonsurfactant Templated Sol–Gel Mesoporous Silica

One-step reduction and simultaneous decoration on various porous substrates: toward oil filtration from water

Bionic robot fish propelled by swinging of flexible pectoral fins driven by artificial muscles