Stimuli-responsive materials are substances that change their properties or behavior in response to external stimuli, such as temperature, pH, light, or electric fields. These materials can undergo physical or chemical transformations, making them useful in various applications, including drug delivery, sensors, and smart textiles. These materials are often designed at the molecular level to react predictably to specific triggers. For example, hydrogels can swell or shrink when exposed to changes in temperature or pH, while shape-memory polymers can return to a predetermined shape when heated. This adaptability makes stimuli-responsive materials valuable in advanced technology and biomedical fields.