Crosslinking Strategy for Constraining the Structural Expansion of Graphene Films during Carbonization: Implications for Thermal Management

Graphene films are accepted as excellent heat dissipation materials due to their ultrahigh thermal conductivity. In general, the graphene film uses graphene oxide (GO) as the raw material through self-assembly, carbonization, and graphitization processes. However, the production and accumulation of a large amount of gas during the carbonization can produce high gas pressure, which causes damage to the ordered stacking structure and seriously affects the thermal conductivity of the graphene film. In this work, we propose a strategy of diamine reagents to crosslink and reduce GO for constraining volume expansion during carbonization. The amine group undergoes nucleophilic substitution and condensation reactions with oxygen-containing functional groups (−COOH, – C–O–C) to form – C–N bonds, which broaden the temperature range of gas production by changing the chemical structure. Compared to dimethylaminopropylamine and N-isopropylethylenediamine, ethylenediamine with symmetrical primary amines can react sufficiently with GO to form a robust structure. Based on these observations, the ethylenediamine-modified film shows a lower expansion rate (115.2%) and higher in-plane thermal conductivity (∼1180 W m–1 K–1) than the pure graphene film (152.6% and ∼980 W m–1 K–1, respectively). This work could be significant in the preparation of graphene films with high thermal conductivity.