## 1 Introduction  
In the past several years, superhydrophobic surfaces have attracted remarkable interest due to their unique wettability for potential applications in self-clean, anti-fog, anti-ice, anti-bacteria, oil-water separation, energy-storage, and drug-release [1; 2; 3; 4; 5; 6; 7]. To obtain these special wetting properties, surface modification has been developed to establish hierarchical micro/nano structures with hydrophobic chemical groups by learning from the exquisite tissues and organs in the biological world, such as lotus leaves and pond skater legs with super hydrophobicity [8]. Based on this bionic mechanism (i.e., the Wenzal and Cassie-Baxter models) [9], many superhydrophobic materials are fabricated from the traditional substrates such as wood, sponge, metal mesh, and fabric via appropriate physical and chemical approaches [10; 11; 12; 13]. These functional materials have many advanced attractive merits and can be applied in both scientific and industrial fields. Most importantly, these raw materials are low cost and simple to acquire. Halloyite clay nanotubes (Al\({}_{2}\)Si\({}_{2}\)O\({}_{5}\)(OH)\({}_{4}\).\(n\)H\({}_{2}\)O, 1:1 layer aluminosilicates) (HNTs), as a kind of environmentally friendly and natural porous nanomaterial, are extensively used in many areas for numerous applications, such as polymer reinforcement, nano catalyst, and absorbing substrates for drug delivery, pollutants removal, and thermal energy storage [6; 14; 15; 16; 17; 18]. However, natural HNTs are sensitive to moisture and it is easy to absorb water into the hollow cylinders because of the hydrophilic gibbsite octahedral sheet (Al-OH) groups existing on the internal surface [19]. This characteristic renders HNT difficult to disperse and a poor adsorptive capacity for hydrophobic organics, which limits its potential candidates as nanomaterials, especially for the preparation of polymeric nanocomposites and supporting porous materials. To combat this drawback, surface modification and functionalization has been used as a promising technique for artificial synthesizing hydrophobic HNTs, aiming to expand their application galleries [20]. Current research on superhydrophobic materials have focused on the utilization of various treatment process, mostly consisting of chemical vapor deposition (CVD), hot pulling, hydrothermal treatment, soft blasting, and sol-gel method for building lotus-leaf-like hierarchical structures [21; 22; 23; 24; 25]. However, as for HNTs, the superhydrophobic modifications are still at an embryonic stage mainly via combination of covalent bond with various alkylsilanes due to the similar siloxane groups (Si-O-Si) presenting on the external surface. For example, [PERSON] et al. developed a novel superhydrophobic HNT with treatment of PDMS (polydimethylsiloxane) at 240 \({}^{\circ}\)C in a closed container, which had a high water contact angle (CA) of up to 157\({}^{\circ}\), and it showed great potential to support phase change materials [6]. [PERSON] et al. introduced ODTMS (octadecyltrimethoxysilane) into the surfaces of HNTs with reaction time of 90 h and a liquid marble agglomerated by modified HNTs was formed with a high CA above 160\({}^{\circ}\), which could be applied in deliverable capsules and bioreactors [20]. Moreover, polyorganosilanes, octadecylsilane coordination with Ag nanoparticles, and polypropylene were also used as surface modifiers to acquire superhydrophobic HNTs [7; 26; 27]. Despite that these modified approaches were actually effective, in most cases, the fabrication routes suffered from a lot of limitations such as harsh processing conditions, tedious sophisticated synthesis environment, and specialized reaction apparatus, which exhibited the main hindrance holding back their extensive practical applications. Furthermore, the remaining waste liquor always comprised of acidic, alkali, and toxic organic solvents that may be harmful to environment.