## 1 Introduction  
Chemical protective clothing (CPC) is a critical way to protect people from exposure to vapors of chemical warfare agents (CWAs). The best-known CWAs, nerve agents (represented by tabun (GA), sarin (GB), soma (GD), and VX) and blister agents (represented by sulfur mustard (HD)), are harmful to the skin. Nerve agents can cause acute poisoning and blister agents cause skin ulceration. Because of the danger of chemical agents, researchers use simulants to study them in the initial stage, and the typical simulants are 2-chloroethyl phenyl sulfide (CEPS) for blister agents and dimethyl methyl phosphonate (DMMP) for nerve agents. Breathable and impermeable types are the main categories of CPC. The impermeable type of CPC generally uses barrier materials and has a reliable protection performance [1; 2; 3]. However, water vapor transmission is obstructed by the barrier materials simultaneously when blocking the CWAs, causing intense heat stress and even fainting [4]. In contrast, the breathable type of CPC, which is usually made of absorptive fiber, has much better physiological comfort [5; 6]. However, the use of adsorbents brings problems such as bulkiness, limited adsorption capacity, poor environmental adaptability, and secondary contamination [7]. Polyelectrolyte membranes usually have a certain microphase separation structure. Under a swelling action, nano-scale water channels are formed in the membrane material, which is conducive to the rapid passage of water molecules, while the passage of poison molecules is limited by the molecular size and molecular polarity. The diffusion coefficient in the membrane is very small, thereby realizing high-efficiency moisture permeability under the long protection time of the membrane material [8]. Ideally, the protective material should be selectively permeable, allowing water to pass through and blocking CWAs. Polyelectrolyte membranes (PEMs) represent an ideal material to solve this contradiction because of their unique microphase separation structure composed of hydrophobic and hydrophilic domains. Nanoscale hydrophilic channels can be formed through the self-assembly process and endow the PEM with selective permeability. The typical PEM materials widely reported so far for CPC applications are polystyrene sulfonic acid (PSSA), perfluorinated ionomers (Nafion), and sulfonated poly(styrene-isobutylene-styrene) triblock copolymer (SIBS) [9; 10; 11; 12; 13; 14; 15; 16; 17; 18]. However, these materials have their own weaknesses. The water/DMMP selectivity of sulfonated SIBS is relatively poor (0.7-35) [18], the cost of Nafion is too high for CPC applications (USD 1600 m\({}^{-2}\) for Nafion 117) [19], and the mechanical properties of PSSA are relatively poor [13]. Graphene is a typical two-dimensional material. It has excellent barrier properties and is considered to be the thinnest high-barrier material in the world. Oxygen-containing functional groups on the graphene oxide (GO) provide steric hindrance, which makes the interlayer spacing larger, and these oxygen-containing functional groups have a tendency of clustering and stacking, so the large gaps of unoxidized parts of the GO sheet are reserved. These gaps form a graphene capillary network inside the GO layers. The 2D graphene nanocapillary network allows the low friction slip of the monolayer water [20]. Due to the electroconductive characteristics of the polyelectrolyte membrane, the incorporation of unmodified GO into the membrane will cause serious phase separation. GO clusters are small particles and are not compatible in the polyelectrolyte membrane casting solution. Therefore, we adopt the method of polymerization grafting, using sodium p-styrene sulfonate (SSS) as the monomer to initiate polymerization on the surface of GO. After the vinyl monomer is initiated, macromolecular free radicals are immediately formed through chain growth.