Strategic Design of Clay‐Based Multifunctional Materials: From Natural Minerals to Nanostructured Membranes

Abstract

Nature not only carefully prepares ingenious raw materials but also continuously inspires and guides human beings to create a wide variety of intelligent materials. As the most abundant mineral resource on earth, clay minerals are no longer synonymous with ceramics and cements. Many natural clay minerals can be exfoliated into single-or few-layered nanosheets with exquisite physicochemical properties, which can be reassembled into functional membranes with a macroscopic controllable size and microscopic ordered structure. They are thus used in many fields including chemistry, biology, energy, and environmental science. Strategic design represents one of the key processes to enhance the value of clay minerals and broaden their applications. In this work, the three frequently used approaches of exfoliation are highlighted and the six routes of assembly including casting, dip-coating, spray coating, vacuum filtration, electrophoretic deposition, and 3D printing are compared. The corresponding principles and advantages are summarized. Representative applications of clay-based multifunctional membranes in protection, separation, responsiveness, flexible electronics, and energy conversion are presented. The challenges and future perspectives of the claybased multifunctional membranes are discussed.

Electrospinning with a spindle-knot structure for effective PM2.5 capture

“…In Fig. 1e, the strips of the HNM-NF filter (2 cm× 10 cm) easily exhibited different extents of in situ twisting (0°, 90°, 180°and 360°) with spiral shape, indicating excellent pliability and flexibility [32]. PM 2.5 filtration performance test was performed with the filters containing different concentrations of HNMs under various humidity levels (Fig.…”

“…S3e). This difference was ascribed to two reasons: (i) most of PM 2.5 particles were collected on the top surface of the filter and rarely penetrated to the bottom surface [8]; (ii) the PM 2.5 particles that penetrated to the bottom surface can be carried away by the airflow on the PCL filter, whereas those particles can be firmly captured on the HNM-NF filter due to the polarized surface and hydrophilicity, resulting in a good filtration performance [32]. Furthermore, HNM-NF filters showed the possibilities for better PM capture capacity because PM was only adsorbed on fibers and no aggregation of bigger particles after 24-h road dust test [1].…”

3D printing of kaolinite clay with small additions of lime, fly ash and talc ceramic powders

“…The presented results support previous findings regarding the DIW technique and its high versatility for printing powdered ceramics and clays. Novel research has been reported with a similar material, kaolin [37], using water glass as an additive. However, no investigations were found reporting the use of the additives investigated here in combination with kaolinite clay.…”

The Progressive Development Of Multifunctional Composite Materials In Different Applications

“…the study proposed 4 different types of coating (A, B, C, and D) and reference. The results of the different coating processes are shown in Figure. Zhou et al [20] studied clay that can be applied in multifunctional membrane technology with nanostructured. In their study, natural clay minerals can be exfoliated into nanosheets with designed properties.…”

“…The study shows that natural clay after manufactured into functional membrane can be applied in chemistry [21], biology [22], energy [23], and environmental issues [23]. The advantages and disadvantages of using the different processes are summarized in Figure. 3, where the data are mined from Zhou et al [20].…”