Should I move from polymer materials and engineering to applied physics?

Sometimes I sit down and really ask myself what I want. The current study of polymer materials and engineering really makes me feel good, and I will learn a lot of new things. However, thinking that my job after graduation would be to study rubber or plastics or oil, I think I really don't like it. On the contrary, I like theoretical physics, just thinking about those atoms or the universe are very exciting. However, our school only has a major in applied physics, not a major in physics. This makes me wonder whether or not to switch to a major (applied physics tends to be more experimental, and I like theoretical physics).