Haixia Dong

Bioinspired Materials: from Low to High Dimensional Structure

The surprising properties of biomaterials are the results of billions of years of evolution. Generally, biomaterials are assembled under mild conditions with very limited supply of constituents available for living organism, and their amazing properties largely result from the sophisticated hierarchical structures. Following the biomimetic principles to prepare manmade materials has drawn great research interests in materials science and engineering. In this review, we summarize the recent progress in fabricating bioinspired materials with the emphasis on mimicking the structure from one to three dimensions. Selected examples are described with a focus on the relationship between the structural characters and the corresponding functions. For one-dimensional materials, spider fibers, polar bear hair, multichannel plant roots and so on have been involved. Natural structure color and color shifting surfaces, and the antifouling, antireflective coatings of biomaterials are chosen as the typical examples of the two-dimensional biomimicking. The outstanding protection performance, and the stimuli responsive and self-healing functions of biomaterials based on the sophisticated hierarchical bulk structures are the emphases of the three-dimensional mimicking. Finally, a summary and outlook are given.

Mussel Inspired Modification of Polypropylene Separators by Catechol/Polyamine for Li-Ion Batteries

Inspired by the remarkable adhesion of mussel, dopamine, a mimicking adhesive molecule, has been widely used for surface modification of various materials ranging from organic to inorganic. However, dopamine and its derivatives are expensive which impede their application in large scale. Herein, we replaced dopamine with low-cost catechol and polyamine (only 8% of the cost of dopamine), which could be polymerized in an alkaline solution and deposited on the surfaces of various materials. By using this cheap and simple modification method, polypropylene (PP) separator could be transformed from hydrophobic to hydrophilic, while the pore structure and mechanical property of the separator remained intact. The uptake of electrolyte increased from 80% to 270% after the hydrophilic modification. Electrochemical studies demonstrated that battery with the modified PP separator had a better Coulombic efficiency (80.9% to 85.3%) during the first cycle at a current density of 0.1 C, while the discharging current density increased to 15 C and the discharge capacity increased by 1.4 times compared to the battery using the bare PP separator. Additionally, the modification allowed excellent stability during manifold cycles. This study provides new insights into utilizing low-cost chemicals to mimic the mussel adhesion and has potential practical application in many fields.

Robust Superhydrophobic Bridged Silsesquioxane Aerogels with Tunable Performances and Their Applications

Aerogels are a family of highly porous materials whose applications are commonly restricted by poor mechanical properties. Herein, thiol-ene chemistry is employed to synthesize a series of novel bridged silsesquioxane (BSQ) precursors with various alkoxy groups. On the basis of the different hydrolyzing rates of the methoxy and ethoxy groups, robust superhydrophobic BSQ aerogels with tailorable morphology and mechanical performances have been prepared. The flexible thioether bridge contributes to the robustness of the as-formed aerogels, and the property can be tuned on the basis of the distinct combinations of alkoxy groups with the density of the aerogels almost unchanged. To the best of our knowledge, the lowest density among the ambient pressure dried aerogels is obtained. Further, potential application of the aerogels for oil/water separation and acoustic materials has also been presented.

Effect of microgel content on the shear and extensional rheology of polyacrylonitrile solution

Crosslinked polyacrylonitrile (cPAN) particles with uniform size were synthesized through precipitation polymerization. The as-formed cPAN nanoparticles were dispersed in polyacrylonitrile (PAN) solutions to form microgels with various contents, which were used as model to study the influence of the microgels on the shear and extensional rheology of PAN solutions. Flow curves of steady shear viscosity displayed shear thinning and followed time–temperature superposition principle. The dependency of activation energy on the content of cPAN microgels indicated that introduction of microgels weakened the temperature sensitivity of PAN solutions. For extensional rheology study, we utilized the capillary thinning rheometry to characterize the elongation relaxation time and apparent extensional viscosity. Study of filament thinning dynamics with a series of system strains confirmed that the higher content of cPAN microgels the lower extensional strength and worse spinnability of the PAN solution.

Robust anti-reflective silica nanocoatings: abrasion resistance enhanced via capillary condensation of APTES

This paper demonstrates a facile and effective improvement of abrasion resistance of silica nanoparticle (NP) based anti-reflective coatings via capillary condensation of 3-aminopropyl triethoxysilane (APTES). The quartz crystal microbalance (QCM) is used to test the abrasion resistance property. The versatility of this developed method is further illustrated by the successful application to the poor heat-resistant polymer substrates.

Spherically aggregated Cu2O–TA hybrid sub-microparticles with modulated size and improved chemical stability

In this paper, tannic acid (TA) was used to assist the fabrication of spherically aggregated Cu2O–TA hybrid sub-microparticles with good chemical stability and controllable sizes. TA exhibited multiple functions in the synthesis: the reductant for the formation of Cu2O crystal seeds, the stabilizer of the primary Cu2O crystals and the protector against the oxidation of Cu2O. A probable mechanism was presumed, including 1) seed formation and TA encapsulation, 2) primary crystal nucleation and growth, and 3) aggregation into spheres. We found that pH played a key role in determining the final morphology of the product while the precursor concentration strongly influenced the size of the particles. At a suitable pH, hierarchically structured Cu2O–TA sub-microspheres with nanocrystals as building blocks were produced. The size of the spheres can be tuned from 130 to 670 nm by adjusting the precursor concentration. Cu2O–TA hybrids exhibited excellent chemical stability against water and oxygen. The method reported here possessed many advantages like cost-effectiveness, facility of preparation, environmental friendliness, chemical stability and excellent adjustability. The properties of the prepared Cu2O particles might facilitate their applications in marine antifouling paints, adsorption materials and antibacterial agents.

Facile preparation of bridged silsesquioxane microspheres with interconnected multi-cavities and open holes

Creating hollow structures in microspheres is attracting increasing interest because of the notable large capacity, high porosity, low density and extended surface area of the hollow microspheres prepared. Herein, facile preparation of bridged silsesquioxane (BSQ) microspheres with interconnected multi-cavities and open-hole structures is presented. The well-developed multi-cavities are derived from the configuration of the water-in-oil-in-water emulsion of the precursor. The condensation of the precursor in the emulsion results in the transition of the liquid precursor to solid BSQ resin, which preserves the emulsion structure and induces the formation of voids. The resultant hollow BSQ microspheres show advantages in controllable cargo delivery.