Guangming Gong

Bio-inspired adhesive superhydrophobic polyimide mat with high thermal stability

Superhydrophobic surface with high solid/liquid adhesion is of great fundamental and technological importance. However, the fabrication of adhesive superhydrophobic polymer surfaces with high stability is rare, which limits the utilization of such surfaces in harsh environments. This paper illustrates a simple electrospinning way to produce fluorinated polyimide nanofibric mat with adhesive superhydrophobicity as well as high thermal stability. The water contact angle on the mat reaches as high as 157.8° and the adhesive force to a water drop is up to 98.3 μN. Moreover, the adhesive superhydrophobic polyimide mat is able to stand extreme heat up to 300 °C. By virtue of the facile electrospinning technique, large-area flexible mats can be easily achieved. Such an electrospun fluorinated polyimide mat will possess broader applications than ordinary organic superhydrophobic surfaces owing to its excellent stability in harsh environments.

A highly durable silica/polyimide superhydrophobic nanocomposite film with excellent thermal stability and abrasion-resistant performance

Superhydrophobic self-cleaning materials are widely applicable in many areas, but the low durability of superhydrophobicity is always a major obstacle for real-world applications. Here we propose a rather simple way to increase durability. We combine electrospinning and polyimides with nano-sized silica to create a durable self-cleaning film. Such films present strong resistance to heat and abrasion, along with thermal insulation. The delicate lotus effect can also be tough and durable.

Multifunctional, marvelous polyimide aerogels as highly efficient and recyclable sorbents

With the increasing awareness of environmental protection, it is imperative to develop advanced materials that can clean up spilled oil and organic contaminants efficiently. Herein, we designed and fabricated a series of novel polyimide (PI) aerogels by freeze-drying. The PI aerogels exhibit excellent absorption capability. The toluene absorption capability even ranked first among reported organic absorbents. The PI aerogels also exhibit good absorption recyclability. Surprisingly, the PI aerogels show high flexibility in liquid nitrogen, and liquid nitrogen absorbed by PI aerogels can be squeezed out repeatedly as if it were water in a sponge. What is more, PI aerogels are also usable as sorbents at high temperature and in harsh acid. These desirable attributes would enable PI aerogels to act as ideal sorbents in extreme environments. Together with thermal insulation and fire-resistance, the multifunctional, marvelous PI aerogels are expected to further extend their practical applications.

Biomimetic “Cactus Spine” with Hierarchical Groove Structure for Efficient Fog Collection

A biomimetic “cactus spine” with hierarchical groove structure is designed and fabricated using simple electrospinning. This novel artificial cactus spine possesses excellent fog collection and water transportation ability. A model cactus equipped with artificial spines also shows a great water storage capacity. The results can be helpful in the development of water collectors and may make a contribution to the world water crisis.

Nanofibrous adhesion: the twin of gecko adhesion.

Inspired by dusty spider dragline silk, we studied the adhesive interaction between artificial nanofibers and their aerosol surroundings. The nanofibers are found to be able to actively capture particulate matters from the environment, exactly as the spider dragline silk does. Examinations prove that such nanofibrous adhesion is insensitive to the chemical nature of the fibers and the physical states of the particulate matter and depends only on the fiber diameters. Such facts indicate that nanofibrous adhesion is a case of dry adhesion, mainly governed by van der Waals force, sharing the same mechanism to gecko adhesion. Nanofibrous adhesion is of great importance and has promising potential. For instance, in this work, nanofibers are fabricated into a thin and translucent filter, which has a filtration performance, as high as 95%, that easily outperformed ordinary ones. We believe that this adhesive property of nanofibers will open up broader applications in both scientific and industrial fields.

Biomimetic "water strider leg" with highly refined nanogroove structure and remarkable water-repellent performance.

The water strider is a wonderful case that we can learn from nature to understand how to stride on the water surface. Inspired by the unique hierarchical micro/nanostructure of the water strider leg, in this article, we designed and fabricated an artificial strider leg with refined nanogroove structure by using an electrospinning and sacrificial template method. A model water strider that was equipped with four artificial legs showed remarkable water-repellent performance; namely, it could carry a load that was about 7 times heavier than its own weight. Characterization demonstrated that, even though the artificial leg did not possess a superhydrophobic surface, the numerous nanogrooves could still provide a huge supporting force for the man-made model strider. This work enlightens the development of artificial water-walking devices for exploring and monitoring the surface of water. Because of the advances of the applied materials, the devices may fulfill tasks in a harsh aquatic environment.

Do Shale Pore Throats Have a Threshold Diameter for Oil Storage

In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries.

A flexible, sandwiched high-performance super-insulation fabric

The rapid development of modern technology has put forward higher requirements on thermal insulation materials in many fields. Due to the inevitable defects of common insulation materials, a novel super-insulation material with high performance should be explored. In this article, a flexible, sandwiched super-insulation polyimide (PI) fabric has been designed and fabricated by using an electrohydrodynamic jet technology simply. This unique sandwiched fabric possessed an ultra-low thermal conductivity (16.7 mW m−1 K−1), excellent mechanical properties and a wide operating temperature range. Furthermore, it still has some other multifunctions, such as great cryogenic resistance, self-extinction and thermal stability. Such a sandwiched PI fabric with remarkable integrated performance will have potential engineering applications under harsh conditions, such as the aerospace field.