You Do Need power plug adapter while traveling from São Tomé and Príncipe to Puerto Rico.

Here is Why You Need An Adapter

The outlet and plug type used in Puerto Rico are A and B and in São Tomé and Príncipe are C and F. This is how they look like.

São Tomé and Príncipe

In São Tomé and Príncipe, outlets of type C and F are in use.

Type C

Type F

Puerto Rico

In Puerto Rico, outlets of type A and B are in use.

Type A

Type B