Hollow Superstructure In Situ Assembled by Single‐Layer Janus Nanospheres toward Electromagnetic Shielding Flame‐Retardant Polyurea Composites

Abstract

A dodecahedral superstructure consisting of a single layer of Janus spheres containing ZIF‐67 nanodots is prepared by in situ polymerization, with ZIF‐67 and bio‐based phytic acid (PA) as templates and dopants. It is used to improve the flame retardant, electromagnetic (EMI) shielding, and thermal conductivity properties of polyurea (PUA). By adding 5 wt% polyaniline@cobalt phytate‐2.0 (PANI@Co‐PA‐2.0), the peak of heat release rate and the peak of smoke production rate are reduced by 54.9 and 59.9%, respectively. The peak of CO and CO2 production also decreased by 46.2 and 53.1%, respectively. A decrease in the absorption intensity of aliphatic and aromatic volatiles is also observed. The fire safety of PUA is greatly improved. In addition, PUA/PANI@Co‐PA‐2.0 exhibits an EMI shielding capability of 22.4 dB with the help of reduced graphene oxide, which confirms the possibility of PUA material application in the field of electromagnetic shielding. The 5 wt% filler increases the tensile strength of the PUA matrix to 6.3 MPa, and the composite material obtains good thermal conductivity. This work provides a viable method for the preparation of a flame‐retardant, conductive, and electromagnetic refractory PUA substrate.

Improving processability and mechanical properties of epoxy resins with biobased flame retardants

“…33 The total smoke production (TSP) offers an insightful parameter for assessing the cumulative smoke production per unit sample area burned. 29,34 Figure 7(d) shows that DPN-5 yields a TSP value of 15.03 m 2 in contrast to that of DPN-0 of 16.98 m 2 . Concurrently, the carbon monoxide production (CO 2 P) of DPN-5 diminishes compared to DPN-0 (Fig.…”

Structure of Metal–Organic Frameworks Eco-Modulated by Acid–Base Balance toward Biobased Flame Retardant in Polyurea Composites

“…In addition, although the hollow structure exposes more active sites, the specific surface area is drastically reduced and expensive MOFs are too wasteful to merely serve as etching templates . Specifically, ZIFs, especially ZIF-67 and ZIF-8, have a specific surface area of 1300–1800 m 2 /g. , Nevertheless, the specific surface areas of a series of PA-functionalized ZIFs (ZnPA@ZIF-8 and PANI@Co–PA-2.0) reported by Bao et al and Bi et al were only 269.5 and 182.2 m 2 /g, respectively. While pursuing high performance, the advantages of different functional components are cleverly integrated to avoid waste of effective resources, which meets the requirements of green chemistry.…”

Large-Scale Fabrication of Tunable Sandwich-Structured Silver Nanowires and Aramid Nanofiber Films for Exceptional Electromagnetic Interference (EMI) Shielding

“…However, the resulting EM pollution brings about a host of problems that seriously affect both human health and the normal operation of high-precision electronic equipment [ 6 , 7 , 8 ]. The development of flexible electronic devices has led to an increasing demand for the application of electromagnetic shielding films, and thus it is important to develop high-performance electromagnetic shielding films [ 9 , 10 , 11 , 12 ]. Nevertheless, current challenges faced by EMI shielding films also include low shielding efficiency, inadequate mechanical properties, and difficulties in large-scale production, which significantly restrict their application and development [ 13 , 14 , 15 ].…”