## 1 Introduction  
Polymer composites have been widely used in modern industry due to their excellent insulation performance, good corrosion resistance, easy processing, excellent chemical stability, and reasonable cost [1, 2, 3]. As a thermosetting resin, epoxy resin is widely used in many fields because of its good mechanical properties, easy processability and adhesion with other materials [4, 5]. However, in some complex and harsh working conditions, such as high humidity environments, continuous operation, and friction conditions, the common epoxy-based composites are not competent [6, 7]. Therefore, it is urgent to develop multifunctional polymer composites that can adapt to complex working conditions. Inspired by lotus leaves, hydrophobic surfaces have drawn great interest in academia and industry [8, 9, 10]. The water contact angle (WCA) of a hydrophobic surface is larger than 90 deg [11, 12], which also reveals that the surface has excellent water repellency and showsgreat potential for application in humid environments. It is generally believed that the combination of low-surface-energy materials and micro-nano structures plays a key role in the formation of hydrophobic or even superhydrophobic surfaces [13; 14]. Fluorinated ethylene propylene resin (FEP), which has multiple fluorine atoms in the molecules, can provide low surface energy for the construction of hydrophobic surfaces [15; 16]. Therefore, polymer composites of EP and FEP can be used to build hydrophobic surfaces, providing adhesion and low surface energy, respectively, and their synergistic effect will promote the improvement in hydrophobic surface performance. One of the biggest problems of hydrophobic materials in practical use is their poor mechanical properties and low wear resistance [17], which severely limits their industrial application. In addition, the equipment will generate a lot of heat under long-term operation and friction. If the heat is not dissipated in time, a large amount of heat accumulation will seriously reduce the reliability, service life, and efficiency of the equipment [18; 19]. Due to the amorphous arrangement and vibrations of the molecular chains, the thermal conductivity of the epoxy resin is very low, only about 0.2 W/(m\(\cdot\)K) [20; 21]. Therefore, it is particularly important to design and prepare materials with hydrophobicity, wear resistance, and thermal conductivity. Carbon felt (CF) is made of carbon fiber and has a three-dimensional network structure [22]. CF has good electrical properties, high porosity, light weight, and high strength [23; 24], which plays a key role in improving mechanical properties such as friction performance of composites and is well applied in aerospace, high-end equipment, and heat conduction fields. Moreover, the thermal conductivity (TC) of carbon fiber is very high [25; 26], but the TC of carbon fiber felt is very low owing to the air remaining in the porous structure. Therefore, how to make better use of the excellent thermal conductivity of carbon fibers, prepare hydrophobic surfaces with high wear resistance and thermal conductivity, and provide basic materials for service in complex environments is of great significance. In this study, APDMS-modified carbon felt (A-CF) was prepared and added to the EP and FEP mixed resin to form A-CF/EP/FEP composites. The A-CF/EP/FEP composites have wear resistance, thermal conductivity, and sustainable hydrophobicity at the same time. For the material design of the A-CF/EP/FEP composites, the high-content FEP (20 30, 40, and 50 wt%) provides low surface energy, the EP has good adhesion, and the A-CF has good bonding with EP and FEP. The WCA of the A-CF/EP/FEP composites with different FEP contents is more than 90\({}^{\circ}\), and the maximum WCA is 109.9 \(\pm\) 2.6\({}^{\circ}\) when the FEP content is 20 wt%. The high hydrophobicity results from the low surface energy of FEP and the microstructure of A-CF.