What substance is formed when $\ce{CF2=CF2}$ is polymerized?

$ \textbf{(A) } \text{Polyethylene} \qquad\textbf{(B) } \text{Polyurethane}\qquad\textbf{(C) } \text{PVC}\qquad\textbf{(D) } \text{Teflon}\qquad$
1. Identify the monomer: The given monomer is $\ce{CF2=CF2}$, which is known as tetrafluoroethylene.
2. Determine the polymerization process: Tetrafluoroethylene undergoes polymerization to form a polymer chain. The polymerization of tetrafluoroethylene can be represented as:
   \[
   n \ce{CF2=CF2} \rightarrow \ce{(-CF2-CF2-)}_n
   \]
3. Identify the polymer: The resulting polymer $\ce{(-CF2-CF2-)}_n$ is known as polytetrafluoroethylene (PTFE), which is commonly referred to as Teflon.

The final answer is $\boxed{\text{Teflon}}$