# Are all monomers in a polymer covalently bonded?

I'm approaching chemistry and I read on Wikipedia that

The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger"

But then the article goes on and it says:

Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science; emerging important areas of the science now focus on non-covalent links.

So now I'm wondering, are there polymers whose monomers are bonded in other ways?

• Look up Titan and Hydro; also nanopolymers are an interesting read: physicsworld.com/cws/article/news/2007/jan/19/… May 17 '17 at 9:12
• A very interesting possibility is to have a large amount of cyclic molecules interlocking with two (or more) neighbours each, like links in a chain. In this case the monomers (each individual ring) would not directly rely on any kind of bonding whatsoever between the rings to stay together, but would be held in such a way due to the "impenetrability" of matter. I think the main effect keeping the polymer together would be the Pauli exclusion principle, which is a rather unique situation. Though it would be marvellous to study such a polymer, it is a distant synthetic dream. May 17 '17 at 13:51
• Circular DNA has the properties @Nicolau_Saker_Neto is talking about. The two strands of double-stranded DNA are twisted around each other, and in circular DNA, you can't separated them without breaking covalent bonds, but they are not connected by covalent bonds. Jan 24 '19 at 20:41
• The second quote is ambiguous. It could be talking about the importance of the (non-covalent) links between the polymer chains. Apr 19 '19 at 11:01

I think your second quote is referring to some polymers such as sodium polyacrylate, $$\ce{[-CH2-CH(COONa)-]_n}$$. This polymer is basically just the sodium salt of polyacrylic acid (or polymerized sodium acrylate). You can see below the ionic bond between the anionic carboxylate group and the sodium cation: