It is clear that it is a little arbitrary to divide the techniques into these two categories.
Every process involves both chemical and physical aspects.
The value in this is it gives a bit of organization to our study. I hope that you can get a similar sense as I have of the division and that it might be helpful. Polymers probably qualify but a polymer by itself has not usually been thought of as a nanostructure. However, we will find a number instances where a small polymeric agglomeration has clearly been a nanostructure, such as with 60 nm diameter latex spheres. Chemists tend to organize atoms together to grow a nanostructure.