Yep, one of those again, although in this case, I'm not sure that I know enough to have all the background, so please feel free to enlighten me if you know more.
So today's battle is: "Interpenetrating Polymer Network" vs. "Double Network", or IPN vs. DN. IPN has the presumption of history on its side (I believe), a term used to describe two independent polymer networks (generally crosslinked ) that are intermeshed at a molecular level. To assembly such a beast, two different reactions are run, either sequentially or simultaneously, but most importantly, there are no chemical bonds connecting the networks. The end result in either case is two truly entangled networks. Interpenetrating polymer network is a great term to describe them as if is accurate, and in my mind, abstruse enough that you need to know what the term means - you can't fake it nor does it mislead. At 11 syllables however, "interpenetrating polymer network" is a mouthful, although IPN flows nicely as an 3 syllable abbreviation .
So now along comes the term "double network" that I first ran into in a paper on hydrogels. The authors of the paper do use IPN to describe their polymers, but seem to prefer using "double network" instead. At first I thought it was just an upstart term, but a search shows that it appears to be limited to just IPN's that interact strongly with water (hydrogels).
So is that the only time DN is used, and if so, what is wrong with IPN?
Part of my problem with this discussion is that I also think "double network" is a pretty good term to use as well. Just like "interpenetrating polymer network", it's accurate and abstruse. It's also only 4 syllables, although DN doesn't quite roll off the tongue as well as IPN does.
This is not like some of the monstrosities that IUPAC has foisted on us, such as replacing "intrinsic viscosity" with "limiting viscosity number", a change that was not asked for or accepted by rheologists and polymer practitioners, but then again, isn't also the case for "double network"?
 When only one network is crosslinked, then you have a semi-interpenetrating polymer network.
 The worst abbreviation in the world? www, as in world wide web. The acronym has 9 syllables, three times that of what is being abbreviated.