Fabrication of highly thermal conductive epoxy/graphite@<scp>La₂O₃</scp> composite coating with anti‐erosion and mechanical flexibility

Abstract Highly thermal conductive polymer coating is delivered from blending thermal conductive fillers, yet sacrificing the mechanical properties, e.g. anti‐erosion, and mechanical flexibility. In this work, highly thermal conductive, mechanical flexible and anti‐erosion epoxy resin (EP)/graphite@La 2 O 3 composite coating was developed via chemically modification. Polydopamine (PDA), γ‐methacryloxypropyltrimethoxysilane and n ‐octyltrichlorosilane were used to graft La 2 O 3 particles onto graphite (graphite@La 2 O 3 ) to enhance interfacial compatibility. Graphite@La 2 O 3 homogeneously dispersed in epoxy forming more thermal conductive pathways and layered structure. In‐plane and cross‐plane thermal conductivity of EP/graphite@La 2 O 3 coating was 2.06 and 1.7 W/(m K), respectively. The temperature of EP/graphite@La 2 O 3 composite coating increased from room temperature to 107.2°C in 60 s while the temperature of EP/graphite coating increased to 59.9°C within 60 s. Furthermore, dispersing graphite@La 2 O 3 into epoxy significantly decreased the weight loss percentage from 0.17 to 0.05 mg/g while the hardness increased from around 7.0–16.77 HV, respectively. The fracture stress and strain of EP/graphite@La 2 O 3 coating was 25 MPa and 6.0%, respectively, which is two times of EP/graphite coating. This is attributed to the chemically grafting La 2 O 3 particles enhanced the interfacial compatibility, homogeneous dispersion and the formation of layered structures in epoxy. This study provides an effective approach to prepare thermal conductive epoxy coatings with multifunctional mechanical properties. Highlights La 2 O 3 nanoparticles grafted on graphite successfully. Mechanical flexibility and anti‐erosion were improved by chemical grafting. Chemical modification improves the interfacial compatibility. The utilization of La 2 O 3 nanoparticles induced the formation of layer structure. Layered structure offsets the stress improving thermal and mechanical property.