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It is well known that graphene nanosheets (GNSs) have many excellent properties. However, it has been a difficult thing to exfoliate graphite into GNSs in a controllable and scalable manner. In this research, a new strategy named xylitol-assisted ball milling exfoliation (XABME) was developed for the scalable preparation of GNSs. The experimental results characterized by a series of measurements showed that GNSs were successfully exfoliated by the XABME strategy. The structure of the prepared nanosheets was featured by large lateral size and ultra-small thickness. Furthermore, the prepared GNSs easily achieved high production yield (≈54%). Lastly, the as-obtained GNSs and cellulose nanofibers (CNF) were compounded to form some nanomaterial films. The prepared films exhibited excellent flexibility and higher thermal conductivity, with the in-plane thermal conductivity of 90 wt% GNS film (8.0 W/(m·K)) being 11.4 times higher than that of the film without GNSs. This shows that GNSs could effectively enhance the thermal conductivity of the CNF matrix and indicate that these prepared films have great potentials in the thermal management of portable mobile devices. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride nanosheets (h‐BNNSs) refer to a class of two‐dimensional materials with promising applications. However, the current method of exfoliating hexagonal boron nitride (h‐BN) into h‐BNNS limits its large‐scale application. Herein, a method was developed to exfoliate h‐BN through sucrose assisted discontinuous, multiple ball milling. A series of defect‐free, ultra‐thin large lateral‐size h‐BNNSs were successfully obtained, with a yield as high as 85 wt %. Finally, the membranes of BNNS obtained by vacuum filtration displayed a good separation performance in different organic pigment solutions. The separation rates of BNNS‐20 membranes for methylene blue and Congo red reached 87 % and 95 %, respectively. The results show that the functionalized h‐BNNSs obtained by sucrose‐assisted discontinuation, multiple ball milling have good stability in water, and hence can be applied to wastewater treatment. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride nanosheets (h-BNNS) and graphene (G) are considered to be the representative materials in the two-dimensional (2D) materials community. h-BNNS and G are considered to exhibit high potential in thermal management materials for their prominent thermal conductivity. However, the conventional methods to synthesize h-BNNS and G are restricted by several problems (e.g., high energy consumption, environmental pollution and complex preparation methods). In the present study, a xylitol (C 5 H 12 O 5)-assisted ball milling method was developed for scalable synthesis of a 2D material mixture of h-BNNS and graphene (BNNS@G). With this method, about 52% yield could be achieved. Moreover, the produced mixture was re-dispersed; it also exhibited high stability in water. The method proposed in this study is capable of effectively transferring green chemistry solutions to the preparation. Besides, a green solution was also proposed to apply the synthesized BNNS@G. The as-obtained BNNS@G was mixed with the cellulose nanofiber solution to form a series of G@BNNS/CNF membranes that exhibited high flexibility and ultrahigh thermal conductivity. Furthermore, 70 wt% BNNS@G membrane (3.4 W/mK) exhibited the in-plane thermal conductivity 300% higher than the membrane without BNNS@G. Thus, it is suggested that the synthesized membranes exhibit high potentials in the thermal management of portable mobile devices. • Xylitol refers to a ball milling agent capable of exfoliating bulk two-dimensional layer material. • Simultaneous forming process of boron nitride nanosheets and graphene nanosheets based on ball milling. • The produced mixture exhibits high dispersion stability in a range of solvents. • The produced mixture is capable of noticeably enhancing the in-plane thermal conductivity of the polymer film. • It is expected that the simultaneous preparing strategy can be adopted to prepare other two-dimensional materials. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride nanosheets (BNNs) are gaining much attention owing to their extraordinary performance; however, difficulties remain in achieving their large-scale preparation and dispersion at high concentration in solvents. A facile yet efficient β-cyclodextrin-assisted mechanochemical exfoliation method is proposed to exfoliate and functionalize hexagonal boron nitride (h-BN). The β-cyclodextrin-assisted ball milling process gave a high yield of 60%, with the resultant BNNs being covalently grafted with hydroxyl, and well dispersed in water and other solvents. The concentration of the hydroxyl-functionalized boron nitride nanosheets (OH-BNNs) reached 3 mg/mL, and was stable for several weeks. Next, we fabricated a membrane based on the resulting OH-BNNs to effectively capture Congo red dye. This work not only offers an environmentally friendly, efficient, solvent-less and extremely cost-effective scalable production method, but also assists in our understanding of the mechanism of exfoliation and functionalization in other layered materials. [ABSTRACT FROM AUTHOR]