## 1 Introduction  
Cotton fabrics are favored by people for their excellent wearing comfort and breathability. However, cotton fabrics can cause many inconveniences to people due to wrinkles in washing and daily wear. With the increasing demand for natural fibers, anti-wrinkle finishing has become an important post-finishing process in the dyeing and finishing of cotton fabric [1, 2]. Anti-wrinkle finishing agents for cotton fabrics can be divided into the following two categories: formaldehyde finishing agents and formaldehyde-free finishing agents. Formaldehyde finishing agents are mainly N-methylrol resin compounds, such as dimethyl dihydroxy ethylene urea (DMDHEU, 2D resin), this type of compound has high reactivity and an excellent cross-linking effect, but the ether bond is easy to hydrolyze and break and releases free formaldehyde, which is harmful to human health [3, 4]. As an alternative finishing agent for 2D resin products, formaldehyde-free finishing agents mainly include dialdehydes, epoxy resins, polyurethanes, silicones, polycarboxylic acids and ionomers. The cotton fabrics with these finishing agents have an excellent wrinkle property, but there are problems such as strong damage to and yellowing of the fabric [5, 6, 7].  
The anti-wrinkle finishing of the cotton fabric chemical cross-linking method generally requires that the cross-linking agent has a suitable molecular size, which can enter the fiber and form cross-links with cellulose on the inside and surface of the fiber. The anti-wrinkle finishing process is similar to the dyeing process of reactive dyes on cotton fabrics (as shown in Figure 1) [4,8]. The specific process is after the cotton fabric is dipped in the anti-wrinkle finishing solution, the crosslinking agent molecules diffuse to the fiber surface boundary layer and adsorb on the surface of the cotton fiber; then, diffusion into the fiber, a cross-linking reaction with cellulose, and fixation within the fiber takes place.  
At present, the development and research of formaldehyde-free anti-wrinkle finishing of cotton fabrics has entered a bottleneck period, and it mainly focuses on the crosslinking mechanism of polycarbonate acid finishing agents, the finishing process, the influence of additives, and the compound application of polycarbonate acids [2,6]. Few researchers have designed and prepared a new type of anti-wrinkle finishing agent starting from the type, number, and reactivity of the crosslinking agent reactive groups. This article took monosaccharides (glucose and fructose), disaccharides (sucrose and trehalose), trisaccharides (rafinose) and tetrasaccharides (stachyose) as the research objects to prepare corresponding glycosyl formaldehyde-free anti-wrinkle finishing agents (the process of preparation is shown in Figure 2). It was also used in the anti-wrinkle finishing of cotton fabrics to evaluate the difference in anti-wrinkle performance. We used Chem3D 19.0 software to calculate the molecular volume of the finishing agent and evaluate its diffusion rate in the fiber; calculated the number of reactive groups, the number of reaction sites and the number of rotatable bonds of the finishing agents; and analyzed the crosslinking properties of different finishing agents. We performed a molecular dynamics simulation with gromacs software, calculated the number of conformations and the conformational energy that the finishing agent existed in within a single cross-linked state, measured the distance between the different cross-linking points, and revealed the relationship between the effective cross-linking range and the cross-linking property of different finishing agents.  
Figure 1: Molecular diffusion model. 1. Diffusing to the fiber surface boundary layer; 2. Being absorbed by the surface of cotton fiber; 3. Diffusing into the fiber; 4. Cross-linking with cellulose and fixing in the fiber.