* Cotton: This provides softness, comfort, and absorbency. It's often the primary component.
* Polyester: Added for durability, wrinkle resistance, and moisture-wicking properties. This helps keep the sweatpants from stretching out too much over time and can make them better for working out.
* Other blends: Sometimes you'll find rayon, spandex, or other fibers added for specific properties like added stretch (spandex) or a softer hand (rayon).
The exact blend varies greatly depending on the brand, the price point, and the intended use (e.g., sweatpants designed for lounging will have a different blend than those intended for athletics). There's no single "college sweatpants" material.