Superhydrophobic surfaces: From natural to biomimetic to functional

Preparation of superhydrophobic surfaces with micro/nano alumina molds

Polymer micro/nano hierarchical structures were successfully formed by photo-nanoimprinting using anodic porous alumina molds. Anodic porous alumina molds with hierarchical structures were prepared by the anodization of an Al substrate with a micro-concave array. The obtained surfaces with hierarchical structures exhibited superhydrophobicity. The hydrophobic properties of the obtained samples were dependent on the surface structures and could be optimized by changing the micro- and nanopatterns in the hierarchical structure.

Superhydrophobic surface with hierarchical structures prepared by nanoimprinting using anodic porous alumina molds.

Fabrication of a superhydrophobic surface with underwater air-retaining properties by electrostatic flocking

The aquatic fern salvinia can retain an air layer on its hairy leaf surface when submerged under water, which is an inspiration for biomimetic applications like drag reduction. In this research, an electrostatic flocking technique is used to produce a hairy surface to mimic the air-trapping performance of the salvinia leaf. Viscose and nylon flocks with different sizes were selected. A volumetric method was established to analyze the air-retaining performance of the flocking samples, Salvinia molesta and lotus leaves as well. Through air volume change analyses, it is found that another factor that can affect the Salvinia molesta air-retaining ability is the curving of the leaf under water. A flocking sample fabricated by a kind of nylon flock is demonstrated to have a comparable air-retaining ability under static conditions as a Salvinia molesta leaf in its flat form.

A flocking sample with underwater air-trapping abilities mimicking the Salvinia molesta leaf was fabricated and evaluated.

Superhydrophobic engineering materials provide a rapid and simple route for highly efficient self-driven crude oil spill cleanup

Traditional superhydrophobic material use depends on two processes: creating a rough structure on a material surface and modifying the rough surface with low surface energy materials. However, common preparation methods are time-consuming, complex and cost-ineffective. Furthermore, these methods usually rely on chemicals, and evidently that will restrict mass preparation and application of superhydrophobic materials. This study reports a simple polypropylene (PP) solution-based process for producing PP hierarchical structures on commercial copper mesh (low surface energy materials), without modifying the low surface energy materials. The hierarchical structures of copper meshes, surface modified with PP, can be rationally controlled by optimizing the PP concentration. The obtained copper mesh showed contact and rolling off angles of 162° and 7°, respectively. Importantly, no significant performance loss was observed after the superhydrophobic copper meshes were continuously and drastically rinsed with 3.5 wt% NaCl solution, or repeated tearing with an adhesive tape for more than 30 cycles, indicating its good durability. After surface modification with PP particles, the copper mesh exhibits both excellent superhydrophobicity and superoleophilicity. Additionally, the as-prepared copper mesh can self-float on water surface when deformed into a “miniature boat” shape. Meanwhile, self-driven spilled oil cleanup was achieved using a superhydrophobic copper mesh-formed miniature boat. The miniature boat can realize energy conservation as well as high efficiency. The cleanup rate of the boat is as high as 97.1%, demonstrating its great potential in environmental remediation applications.

Traditional superhydrophobic material use depends on two processes: creating a rough structure on a material surface and modifying the rough surface with low surface energy materials.

Durable superhydrophobic and superamphiphobic polymeric surfaces and their applications: A review

Wetting control is essential for many applications, such as self-cleaning, anti-icing, anti-fogging, antibacterial action as well as anti-reflection and friction control. While significant effort has been devoted to fabricate superhydrophobic/superamphiphobic surfaces (repellent to water and other low surface tension liquids), very few polymeric superhydrophobic/superamphiphobic surfaces can be considered as durable against various externally imposed stresses (e.g. application of heating, pressure, mechanical forces, chemical, etc.). Therefore, durability tests are extremely important for applications especially when such surfaces are made of "soft" materials. Here, we review the most recent and promising efforts reported towards the realization of durable, superhydrophobic/superamphiphobic, polymeric surfaces emphasizing the durability tests performed, and some important applications. We compare and put in context the scattered durability tests reported in the literature, and present conclusions, perspectives and challenges in the field.

A Wettability Metric for Characterization of Capillary Flow on Textured Superhydrophilic Surfaces

Surface wettability is typically characterized by measuring the static contact angle of a sessile droplet placed on the surface. For extremely wetting surfaces on which liquid spontaneously spreads into a thin liquid film, the near-zero static contact angle is not amenable to measurement and does not fully describe the wetting behavior. There are unmet needs in microfluidics, boiling heat transfer enhancement, and antifogging applications for a metric to characterize highly wetting (i.e., superhydrophilic) textured surfaces based on their capillary-driven liquid pumping performance, as a supplement to the contact angle for this highly wetting regime. To describe the wetting behavior, the textured surface can be approximated as a thin porous layer through which the liquid spreads. An analytical model is developed for the volumetric flow in this layer, which reveals a single superhydrophilicity metric that captures the wetting behavior for a given liquid. A simple experimental approach is proposed to characterize this metric by measuring the volumetric liquid intake into the surface from a filled capillary tube. This approach is validated by characterizing micropillared superhydrophilic surfaces of known geometry; the predicted and measured wetting behaviors show good agreement. The metric proposed in this study offers a simple approach for accurately characterizing and differentiating highly wetting surfaces based on their liquid pumping ability.

Directional growth of Ag nanorod from polymeric silver cyanide: A potential substrate for concentration dependent SERS signal enhancement leading to melamine detection

Attention has been directed to prepare exclusive one-dimensional silver nanostructure from the linear inorganic polymer AgCN. Successive color change from yellow to orange, to red and finally to green reflects the evolution of high yielding Ag nanorods (NRs) from well-known -[Ag-CN]- chains of polymeric AgCN at room temperature. The parental 1D morphology of AgCN is retained within the as-synthesized Ag NRs. So we could successfully exploit the Ag NR for surface-enhanced Raman scattering (SERS) studies for sensing a popular milk adulterant melamine down to picomolar level. We observed interesting concentration dependent selective SERS band enhancement of melamine. The enhanced ~1327cm^-1 SERS signal intensity at lower concentration (10^-9 and 10^-12M) of melamine speaks for the preferential participation of -C-N of melamine molecule with Ag surface. On the other hand, '-NH₂' group together with ring 'N' participation of melamine molecule onto Ag surface suggested an adsorptive stance at higher (10^-3-10^-7M) concentration range. Thus the binding modes of the molecule at the Ag surface justify its fluxional behavior.

Biomimetic Superhydrophobic Biobased Polyurethane-Coated Fertilizer with Atmosphere "Outerwear"

The development of efficient biobased controlled-release fertilizers has captured much research attention because of the environmental concerns and food scarcity problems. In this work, a biomimetic superhydrophobic biobased polyurethane-coated fertilizer (SBPF) was successfully fabricated by increasing surface roughness and reducing surface energy of polyurethane (PU) coating. The green PU coating was synthesized from low-cost, biodegradable, and renewable cottonseed oil. The nutrient release longevity of SBPF revealed 2-fold enhancement compared with the normal biobased PU-coated fertilizer (BPF). The significant improvement of nutrient release characteristics can be attributed to the atmosphere "outerwear" which ensured the nonwetting contact of water with superhydrophobic surfaces in gas state instead of in liquid state. The new concept introduced in this study can inform the development of the next generation of biobased controlled release fertilizers.

Robust Fluorine-Free Superhydrophobic Amino-Silicone Oil/SiO2 Modification of Electrospun Polyacrylonitrile Membranes for Waterproof-Breathable Application

Superhydrophobic waterproof-breathable membranes have attracted considerable interest owing to their multifunctional applications in self-cleaning, anti-icing, anticorrosion, outdoor tents, and protective clothing. Despite the researches pertaning to the construction of superhydrophobic functional membranes by nanoparticle finishing have increased drastically, the disconnected particle component is easy to fall off from the membranes under deformation and wear conditions, which has restricted their wide use in practice. Here, robust superhydrophobic microporous membranes were prepared via a facile and environmentally friendly strategy by dip-coating amino-silicone oil (ASO) onto the electrospun polyacrylonitrile (PAN) membranes, followed by SiO₂ nanoparticles (SiO₂ NPs) blade coating. Compared with hydrophilic PAN membranes, the modified membranes exhibited superhydrophobic surface with an advancing water contact angle up to 156°, after introducing ASO as low surface energy substance and SiO₂ NPs as filler to reduce the pore size and construct the multihierarchical rough structure. Varying the concentrations of ASO and SiO₂ NPs systematically, the PAN electrospun membranes modified with 1 wt % ASO and 0.1 wt % SiO₂ NPs were endowed with good water-resistance (74.3 kPa), relative low thermal conductivity (0.0028 W m^-1 K^-1), modest vapor permeability (11.4 kg m^-2 d^-1), and air permeability (20.5 mm s^-1). Besides, the inorganic-organic hybrid coating of ASO/SiO₂ NPs could maintain its superhydrophobicity even after 40 abrasion cycles. The resulting membranes were found to resist variations on the pH scale from 0 to 12, and retained their water repellent properties when exposed to harsh acidic and alkali conditions. This facile fabrication of durable fluorine-free superhydrophobic membranes simultaneous with good waterproof-breathable performance provides the advantages for potential applications in self-cleaning materials and versatile protective clothing.

Surface topology affects wetting behavior of Bacillus subtilis biofilms

The colonization of surfaces by bacterial biofilms constitutes a huge problem in healthcare and industry. When attempting biofilm inactivation or removal, it is crucial to sufficiently wet the biofilm surface with antibacterial agents; however, certain biofilms efficiently resist wetting, and the origin of this behavior remains to date unclear. Here, we demonstrate that, depending on the growth medium used, the model bacterium Bacillus subtilis can form biofilm colonies with distinct surface properties: we find either hydrophilic or two variants of hydrophobic behavior. We show that those differences in biofilm wetting correlate with distinct surface topologies which, in turn, give rise to different physical wetting regimes known from lotus leaves or rose petals. Forming biofilms with different wetting properties may help bacteria to survive in both arid and humid conditions. Furthermore, converting the surface polarity of a biofilm could facilitate their removal from surfaces by increasing their wettability.

A biofilm’s surface structure affects its susceptibility to wetting, influencing persistence and suggesting strategies for biofilm removal. Effective wetting of biofilm surfaces is essential for combatting them with antibacterial agents. Resistance to the procedures currently available for removing biofilms is a huge problem in healthcare. Researchers in Germany led by Oliver Lieleg at the Technical University of Munich found that Bacillus subtilis bacteria can form colonies with different surface structures that either resist or assist wetting. This structural variability in their biofilms may allow the bacteria to adapt to survive in either arid or humid conditions. The insight that environmental conditions can influence biofilm wettability should spur research to control this natural variation. Learning how to convert biofilms into more readily wetted forms may greatly assist their removal in healthcare situations.

Durable and Hydrophobic Organic-Inorganic Hybrid Coatings via Fluoride Rearrangement of Phenyl T12 Silsesquioxane and Siloxanes

There have been many successful efforts to enhance the water shedding properties of hydrophobic and superhydrophobic coatings, but durability is often a secondary concern. Here, we describe durable and hydrophobic coatings prepared via fluoride catalyzed rearrangement reaction of dodecaphenylsilsesquioxane [PhSiO_1.5]₁₂ (DDPS) with octamethylcyclotetrasiloxane (D₄). Hydrophobic properties and wear resistance are maximized by incorporating both low surface energy moieties and cross-linkable moieties into the siloxane network. Water contact angles as high as 150 ± 4° were achieved even after 150 wear cycles with SiC sandpaper (2000 grit, 2 kPa). These hybrid organic-inorganic copolymers also have high thermal stabilities after curing at 250 °C (T_d5% ≥ 340 °C in air) due to the siloxane network with a maximum T_d5% of >460 °C measured for the system with the highest silsesquioxane content. The coating systems presented here offer a unique combination of hydrophobicity and mechanical/thermal stability and could greatly expand the utility of water repellent coatings.

Multicomponent Droplet Evaporation on Chemical Micro-Patterned Surfaces

The evaporation and dynamics of a multicomponent droplet on a heated chemical patterned surface were presented. Comparing to the evaporation process of a multicomponent droplet on a homogenous surface, it is found that the chemical patterned surface can not only enhance evaporation by elongating the contact line, but also change the evaporation process from three regimes for the homogenous surface including constant contact line (CCL) regime, constant contact angle (CCA) regime and mix mode (MM) to two regimes, i.e. constant contact line (CCL) and moving contact line (MCL) regimes. The mechanism of contact line stepwise movement in MCL regimes in the microscopic range is investigated in detail. In addition, an improved local force model on the contact line was employed for analyzing the critical receding contact angles on homogenous and patterned surfaces. The analysis results agree well for both surfaces, and confirm that the transition from CCL to MCL regimes indicated droplet composition changes from multicomponent to monocomponent, providing an important metric to predict and control the dynamic behavior and composition of a multicomponent droplet using a patterned surface.

Diversity of Cuticular Micro- and Nanostructures on Insects: Properties, Functions, and Potential Applications

Insects exhibit a fascinating and diverse range of micro- and nanoarchitectures on their cuticle. Beyond the spectacular beauty of such minute structures lie surfaces evolutionarily modified to act as multifunctional interfaces that must contend with a hostile, challenging environment, driving adaption so that these can then become favorable. Numerous cuticular structures have been discovered this century; and of equal importance are the properties, functions, and potential applications that have been a key focus in many recent studies. The vast range of insect structuring, from the most simplistic topographies to the most elegant and geometrically complex forms, affords us with an exhaustive library of natural templates and free technologies to borrow, replicate, and employ for a range of applications. Of particular importance are structures that imbue cuticle with antiwetting properties, self-cleaning abilities, antireflection, enhanced color, adhesion, and antimicrobial and specific cell-attachment properties.

Multifunctional hollow superhydrophobic SiO2 microspheres with robust and self-cleaning and separation of oil/water emulsions properties

Superhydrophobic materials have drawn great attention due to its' remarkable non-wetting properties and applications in many fields. In this paper, we synthesize a hollow superhydrophobic SiO₂ powder by typical template method and self-assembly functionalization. Robustness of many superhydrophobic surfaces has become the development bottleneck for industrial applications. Aiming at this problem, the adhesive epoxy resin is specially taken to use as the binding layer between superhydrophobic SiO₂ powder and substrates to create robust superhydrophobic coating. The mechanical durability of the obtained superhydrophobic coating is evaluated by a cyclic sandpaper abrasion. Also, the chemical stability of this superhydrophobic coating is assessed by exposuring it to different pH conditions and UV irradiation, respectively. Significantly, because of the special structure and superhydrophobicity/superoleophilicity of the hollow microspheres, these hollow superhydrophobic SiO₂ powders manifest great oil-adsorbing capacity, which thus can be used to separate oil/water mixtures and remove oil from oil-in-water emulsions.

Biomimetic Bubble-Repellent Tubes: Microdimple Arrays Enhance Repellency of Bubbles Inside of Tubes

The adhesion of bubbles underwater remains the greatest cause of malfunctions in applications such as microfluidics, medical devices, and heat exchangers. Recently, the combination of oxidization and peeling the top layer of self-organized honeycomb films with an adhesive tape resulted in the formation of an ultra-bubble-repellent and pillared polymer surface structure. However, the fabrication of honeycomb films on the inner surface of tubes and the formation of structured hydrophilic textures by peeling the top layer of honeycomb films still remain problematic. In this report, a simple fabrication technique for producing a honeycomb-patterned polymer film on the interior of a tube by dip-coating a polymer solution and blowing humid air in the tube is described. Furthermore, an ultra-bubble-repellent dimple-arrayed structure was fabricated by applying ultrasonication to the honeycomb structure formed on the interior surface of the tubes.

Constructing Fluorine-Free and Cost-Effective Superhydrophobic Surface with Normal-Alcohol-Modified Hydrophobic SiO2 Nanoparticles

Superhydrophobic coatings have drawn much attention in recent years for their wide potential applications. However, a simple, cost-effective, and environmentally friendly approach is still lacked. Herein, a promising approach using nonhazardous chemicals was proposed, in which multiple hydrophobic functionalized silica nanoparticles (SiO₂ NPs) were first prepared as core component, through the efficient reaction between amino group containing SiO₂ NPs and the isocyanate containing hydrophobic surface modifiers synthesized by normal alcohols, followed by simply spraying onto various substrates for superhydrophobic functionalization. Furthermore, to further improve the mechanical durability, an organic-inorganic composite superhydrophobic coating was fabricated by incorporating cross-linking agent (polyisocyanate) into the mixture of hydrophobic-functionalized SiO₂ NPs and hydroxyl acrylic resin. The hybrid coating with cross-linked network structures is very stable with excellent mechanical durability, self-cleaning property and corrosion resistance.

Hydrophobic functionalization of jute fabrics by enzymatic-assisted grafting of vinyl copolymers

Mechanism of grafting of vinyl monomers onto the lignin molecules of jute fabrics.

Understanding the Role of Dynamic Wettability for Condensate Microdrop Self-Propelling Based on Designed Superhydrophobic TiO2 Nanostructures

The ability to release the adhered drops on superhydrophobic surfaces is very important for self-cleaning, antifrosting/icing, microfluidic device, and heat transfer applications. In this paper, three types of in situ electrochemical anodizing TiO₂ nanostructure films are rationally designed and fabricated on titanium substrates with special superwettability, viz., TiO₂ nanotube arrays, irregular TiO₂ nanotube arrays, and hierarchical TiO₂ particle arrays (HTPA), and their corresponding behavior in condensate microdrop self-propelling (CMDSP) is investigated. Compared to the flat titanium counterpart, all three types of rough TiO₂ samples demonstrate a uniform distribution of smaller microscale droplets. Among the treated surfaces, the HTPA possesses the highest condensate density, and more than 80% of the droplets possess a diameter below 10 μm. Theoretical analysis indicates that the feature is mainly due to the morphology and structure induced extremely low droplet adhesion on super-antiwetting TiO₂ hierarchical surfaces, where the excess surface energy released from the migration leads to the self-propelling of merged microdrop. This work offers a way to rationally construct CMDSP surfaces with excellent self-cleaning, antifrosting/icing ability, and enhanced condensation heat transfer efficiency.

Wrinkled single-layer graphenes fabricated by silicon nanopillar arrays

The degree of crumpling affects the optoelectronic properties of graphene, which are very important for the performance of graphene-based devices and materials. In this article, we report an approach to tune the formation of wrinkles on single-layer graphene (SLG) by silicon nanopillar (SNP) arrays. By using gold nanoparticles as an etching mask, SNP arrays with different heights could be prepared by tuning the duration of etching. The formation of wrinkles on these SNP arrays was studied systematically. We found that thermal treatment could lead to a wrapping behavior of graphene around SNP arrays, which was accompanied by the emergence of many more wrinkles. Controllable wettability, conductivity and transmittance were demonstrated. This ability to tune wrinkles using SNP arrays can be employed to engineer the fabrication of graphene-related devices and other optoelectronic applications.

A new kind of transparent and self-cleaning film for solar cells

A kind of one step and in situ etching method is developed to fabricate a highly optically transparent and flexible self-cleaning superhydrophobic film (SSF). This SSF exhibits a very rough surface morphology with hierarchical structure, which makes it have a contact angle of 154.6° and a sliding angle of smaller than 1°. And the SSF can also be self-cleaned in the wind. The SSF hierarchical structure scatters the incident light, but it almost doesn't attenuate the light. So the SSF has antireflection properties and a high light transmittance of 94%. The excellent self-cleaning property, high light transmittance and antireflection property mean that the SSF greatly enhances the performance of solar cells in practical working conditions. The solar cell's efficiency maintains at 95.8% of its initial value after covering with the SSF, which is about 1.7 times higher than that of the solar cell covered with dust, as in practical conditions.

Superhydrophobic materials for biomedical applications

Superhydrophobic surfaces are actively studied across a wide range of applications and industries, and are now finding increased use in the biomedical arena as substrates to control protein adsorption, cellular interaction, and bacterial growth, as well as platforms for drug delivery devices and for diagnostic tools. The commonality in the design of these materials is to create a stable or metastable air layer at the material surface, which lends itself to a number of unique properties. These activities are catalyzing the development of new materials, applications, and fabrication techniques, as well as collaborations across material science, chemistry, engineering, and medicine given the interdisciplinary nature of this work. The review begins with a discussion of superhydrophobicity, and then explores biomedical applications that are utilizing superhydrophobicity in depth including material selection characteristics, in vitro performance, and in vivo performance. General trends are offered for each application in addition to discussion of conflicting data in the literature, and the review concludes with the authors' future perspectives on the utility of superhydrophobic biomaterials for medical applications.

A Robust Epoxy Resins @ Stearic Acid-Mg(OH)2 Micronanosheet Superhydrophobic Omnipotent Protective Coating for Real-Life Applications

Superhydrophobic coating has extremely high application value and practicability. However, some difficult problems such as weak mechanical strength, the need for expensive toxic reagents, and a complex preparation process are all hard to avoid, and these problems have impeded the superhydrophobic coating's real-life application for a long time. Here, we demonstrate one kind of omnipotent epoxy resins @ stearic acid-Mg(OH)2 superhydrophobic coating via a simple antideposition route and one-step superhydrophobization process. The whole preparation process is facile, and expensive toxic reagents needed. This omnipotent coating can be applied on any solid substrate with great waterproof ability, excellent mechanical stability, and chemical durability, which can be stored in a realistic environment for more than 1 month. More significantly, this superhydrophobic coating also has four protective abilities, antifouling, anticorrosion, anti-icing, and flame-retardancy, to cope with a variety of possible extreme natural environments. Therefore, this omnipotent epoxy resins @ stearic acid-Mg(OH)2 superhydrophobic coating not only satisfies real-life need but also has great application potential in many respects.

Cicada Wing Surface Topography: An Investigation into the Bactericidal Properties of Nanostructural Features

Recently, the surface of the wings of the Psaltoda claripennis cicada species has been shown to possess bactericidal properties and it has been suggested that the nanostructure present on the wings was responsible for the bacterial death. We have studied the surface-based nanostructure and bactericidal activity of the wings of three different cicadas (Megapomponia intermedia, Ayuthia spectabile and Cryptotympana aguila) in order to correlate the relationship between the observed surface topographical features and their bactericidal properties. Atomic force microscopy and scanning electron microscopy performed in this study revealed that the tested wing species contained a highly uniform, nanopillar structure on the surface. The bactericidal properties of the cicada wings were investigated by assessing the viability of autofluorescent Pseudomonas fluorescens cells following static adhesion assays and targeted dead/live fluorescence staining through direct microscopic counting methods. These experiments revealed a 20-25% bacterial surface coverage on all tested wing species; however, significant bactericidal properties were observed in the M. intermedia and C. aguila species as revealed by the high dead:live cell ratio on their surfaces. The combined results suggest a strong correlation between the bactericidal properties of the wings and the scale of the nanotopography present on the different wing surfaces.

Dynamic Study of Liquid Drop Impact on Supercooled Cerium Dioxide: Anti-Icing Behavior

This work deals with the anti-icing behavior at subfreezing temperatures of CeO2/polyurethane nanocomposite coatings with and without a stearic acid treatment on aluminum alloy substrates. The samples ranged from superhydrophilic to superhydrophobic depending on surface morphology and surface functionalization. X-ray photoelectron spectroscopy was used to determine the surface composition. The anti-icing behavior was studied both by importing fog into a chamber with controlled atmosphere at subzero temperatures and by conducting experiments with drop impact velocities of 1.98, 2.8, 3.83, and 4.95 m/s. It was found that the ice-phobicity of the ceramic/polymer nanocomposite coating was dependent on the surface roughness and surface energy. Water drops were observed to completely rebound from the surface at subfreezing temperatures from superhydrophobic surfaces with small contact angle hysteresis regardless of the impact velocity, thus revealing the anti-icing capability of such surfaces.

Characterization for Cassie-Wenzel wetting transition based on the force response in the process of squeezing liquid drops by two parallel superhydrophobic surfaces

Application of superhydrophobic surfaces is partly limited by the escaping of the entrapped air beneath the liquid sitting on the superhydrophobic surfaces, i.e., the so-called Cassie-Wenzel wetting transition. Here, to characterize this wetting transition, a linear force response relation with certain abnormal systematic deflection showing the wetting transition information is constructed for the process of squeezing the test liquid drop by two parallel structured (superhydrophobic) surfaces. The linear force response relation is validated by replotting the experimental data from the former work. And then the wetting transition information is investigated on a numerically generated force response curve with certain errors by taking into account the liquid pressure variation during the wetting transition. Results show that the wetting transition can cause an obvious bulge on the linear force response curve. We believe that this method has a potential application in characterizing the robustness of superhydrophobic surfaces.

Advances in preparation, modification, and application of polypropylene membrane

Polypropylene (PP) is one of the most used polymers for microporous membrane fabrication due to its good thermal stability, chemical resistance, mechanical strength, and low cost. There have been numerous studies reporting the developments and applications of PP membranes. However, PP membrane with high performance is still a challenge. Thus, this article presents a comprehensive overview of the advances in the preparation, modification and application of PP membrane. The preparation methods of PP membrane are firstly reviewed, followed by the modification approaches of PP membrane. The modifications includes hydrophilic and superhydrophobic modification so that the PP membranes become more suitable to be applied either in aqueous applications or in non-aqueous ones. The fouling resistant of hydrophilized PP membrane and the wetting resistant of superhydrophobized PP membrane are then reviewed. Finally, special attention is given to the various potential applications and industrial outlook of the PP membranes.