Comment by twic

Right, so if i've got this right, 4,4'-oxydianiline is this (pairs of parens are supposed to be circles denoting benzene rings; apologies for writing out the carbons, i can't do plain hexagons):

        C - C       C - C
       /     \     /     \
  H2N-C  ( )  C-O-C  ( )  C-NH2
       \     /     \     /
        C - C       C - C

The paraformaldehyde does its job as monomeric formaldehyde (the double quote is a double bond running vertically, horrific i know):

     O
     "
  HO-C-OH

And the polymerisation is a straightforward condensation of the formaldehyde with one of the amines, so the monomer is:

           C - C       C - C      O
          /     \     /     \     "
  ...-NH-C  ( )  C-O-C  ( )  C-NH-C-...
          \     /     \     /
           C - C       C - C

And here's a monomer with a bit of its neighbourhood:

  - C      O      C - C       C - C      O      C -
     \     "     /     \     /     \     "     /
   )  C-NH-C-NH-C  ( )  C-O-C  ( )  C-NH-C-NH-C  (
     /           \     /     \     /           \
  - C             C - C       C - C             C -

There's nothing really radical in terms of the building blocks, but it's a novel combination. Cool.

I had never come across oxydiamine before, but i get the impression it's a common component in polymers, and it looks fairly boring and inert. I guess it's not a single big aromatic system, right? Wrong number of electrons.

The reason this is described as a "hemiaminal" is because the formaldehyde carbon can do keto-enol tautomerism and turn into this:

  - C      OH     C -
     \     |     /
   )  C-NH-C-NH-C  (
     /     |     \
  - C      OH     C -

Which has hydroxyl groups and nitrogens on the same carbon, and so is a hemiaminal.

I couldn't figure out the "further cyclize at high temperatures, producing poly(hexahydrotriazine)s", though. Does that mean cyclising using linkages like this? Or is there some way the chains can crosslink?