How does Liquid Glue ensure long-term adhesion without falling off?

Liquid Glue is widely used in many fields. Its strong adhesion and long-term non-falling characteristics are important reasons for its popularity. This involves many factors such as the composition of liquid glue, curing mechanism and interaction with the surface of the adherend.
First of all, the composition of liquid glue is the basis for determining its adhesion. High-quality liquid glue usually contains high-performance polymers. These polymer molecules have a special structure that allows them to fully contact the surface of the adherend when in liquid state. For example, acrylic polymers are one of the main components of many liquid glues. Its molecular chain contains active groups that can form chemical bonds or intermolecular forces with the microstructure of the adherend surface. When the glue is applied to the surface of an object, the polymer molecules will quickly diffuse and fill the tiny pores on the surface of the adherend, forming a microscopic chimeric effect.
Secondly, the curing process of liquid glue is crucial to ensure long-term adhesion. Curing can be physical curing or chemical curing. Physical curing, such as solvent-evaporating glue, after coating, the solvent gradually evaporates, the concentration of the glue increases, the polymer molecules approach each other and entangle, forming a strong bond. Chemical curing glue, on the other hand, cures through chemical reactions. For example, some epoxy glues undergo a cross-linking reaction after mixing the two components. This cross-linking reaction forms a three-dimensional network structure, which greatly enhances the cohesion of the glue and the adhesion to the adherend. During the curing process, suitable environmental conditions such as temperature and humidity are also critical. Generally speaking, most glues cure best within a suitable temperature range because temperature affects the rate of chemical reactions and the speed of molecular movement.
A good match between the liquid glue and the surface of the adherend is also a factor in ensuring long-term non-falling. Different adherend materials have different surface properties, such as roughness, chemical composition, etc. For metal surfaces, some liquid glues containing special additives can form chemical bonds with the metal surface to enhance the bonding effect. For materials such as plastics and wood, the glue needs to be able to adapt to the polarity and microstructure of their surfaces. For example, for plastics with lower polarity, using glues with similar polarity can better achieve bonding. Moreover, pre-treating the surface of the adherend before pasting can significantly improve the bonding effect. For example, sanding the wood surface can increase its roughness, allowing the glue to adhere better; cleaning the metal surface can remove oil and impurities, creating good conditions for the glue to form a chemical bond with the metal.