Facile Construction of a Flexible Film with Ultrahigh Thermal Conductivity and Excellent Flame Retardancy for a Smart Fire Alarm

Abstract

Design and development of intelligent fire warning materials with rapid response capabilities has always been an urgent need for the safety of many flammable materials in their applications. Herein, an aminated black phosphorene (BP-NH 2 ) prepared by ball milling was employed to connect with graphene oxide (GO) via covalent bonds to fabricate a flexible film with ultrahigh thermal conductivity and remarkable flame retardancy. The thermal diffusivity of the RPNG 20 film is as high as 1496.87 ± 51.11 mm 2 s −1 , and its thermal conductivity is also up to 1085.74 ± 37.08 W m −1 K −1 , which is in full agreement with the theoretical calculation value (1086.9 ± 59.1 W m −1 K −1 ) of the multilayer graphene nanosheets reported in the previous literature. The effective medium theoretical calculations show that the interface thermal resistance has been reduced to 1/367 of that of pure graphene, which promotes the heat transfer of phonons. Simultaneously, it displays excellent flame-retardant properties. The peak of the heat release rate (PHRR) value is only 12.46 W g −1 , resulting in a 96.57% decrease compared with that of the pure GO film (363.17 W g −1 ), which is attributed to the formation of an intumescent flame-retardant system. More importantly, when encountering a flame attack, the unreduced flexible film demonstrates an extremely fast fire alarm response capability of less than 1 s and can continue to work after leaving the fire, which is ascribed to the high degree of carbonization after contacting with fire. This covalent linkage strategy provides a new thought for the preparation of multifunctional films to improve the fire prevention and protection response capabilities in the smart fire alarm device.

The gorgeous transformation of paper: from cellulose paper to inorganic paper to 2D paper materials with multifunctional properties

“…With the rapid development of the electronics industry, thermal management has gradually become a crucial problem, whether it is for production or safety, owing to increased levels of dissipated power density. 204–207 Thus, to alleviate this problem, materials with high thermal conductivity, availability, and possibilities for industrial application need to be developed. Some of the traditional thermal conductivity materials that have emerged include metals and their oxides, ceramics, polymer, and carbon materials.…”

“…Some of the traditional thermal conductivity materials that have emerged include metals and their oxides, ceramics, polymer, and carbon materials. 206 Among them, carbon materials are getting significant attention, especially with the advent of some allotropes such as graphene, reduced graphene oxide (RGO) and carbon nanotubes (CNTs). 204 For example, graphene has an ultrahigh thermal conductivity of 3500–5300 W m −1 K −1 compared with some metallic heat sinks.…”

“…205,210,211 In addition, GO sheets, which can be a precursor of graphene, not only have structural defects and a large number of oxygen-containing functional groups but also have grain boundaries, which cause thermal resistance for substantial phonon scattering. 206,212 For RGO paper or films, the reduction process can effectively remove most of the oxygen-containing functional groups, but a large number of defects and gaps cannot be eliminated. 206 Accordingly, some strategies have been developed to effectively solve this problem.…”

“…206,212 For RGO paper or films, the reduction process can effectively remove most of the oxygen-containing functional groups, but a large number of defects and gaps cannot be eliminated. 206 Accordingly, some strategies have been developed to effectively solve this problem.…”

“…Recently, some groups utilized covalent bonding to improve the interface interaction between fillers and GO, which is meaningful for enhancing the thermal conductivity of composite materials. 206,219,220 For example, Qu et al 206 prepared a flexible film with ultrahigh thermal conductivity and significant flame retardancy through covalent binding between the amino groups of amino-functionalized BP (BP–NH 2 ) and carboxyl groups of GO, followed by reduction reaction. The covalent connection formed between adjacent GO nanosheets by the BP–NH 2 sheets can eliminate the gap between adjacent graphene nanosheets, thereby forming a smooth thermal path to reduce the interface thermal resistance.…”