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I just learend about an interpenetrating polymer network (IPN) and that this is a way of mixing polymers. But I thought it was thermodynamically impossible to mix 2 polymers because in ∆G= ∆H -T.∆S the enthropy will never be big enough to overcome ∆H. So why is it possible with an interpenetrating polymer network (IPN)??

thanks in advance

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    $\begingroup$ It is thermodynamically possible to mix gases, sometimes liquids, and sometimes even solids. What is so special about polymers? Why would it be impossible to mix them? $\endgroup$ – Ivan Neretin Oct 13 '15 at 17:31
  • $\begingroup$ because ∆H= (δ stof 1 - δ stof 2)^2 (with δ hildebrand solubility parameter.) and because of the ^2 it's always positive. so it's the enthropy ∆S that has to overcome ∆H in ∆G= ∆H -T.∆S so that ∆G = - so that the mixing is thermodynamically possible. but if you only have some long polymers the enthropy is too low to overcome the ∆H $\endgroup$ – ward Oct 13 '15 at 18:04
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    $\begingroup$ Now you are explaining the distinctive features of polymers in terms which only make sense for polymers. But that's not important anyway. Forget thermodynamics. Imagine two polymers which were polymerized simultaneously into an IPN, and remain that way. Probably they would like to untangle, but how? That's kinetically impossible. $\endgroup$ – Ivan Neretin Oct 13 '15 at 18:18
  • $\begingroup$ ah ok, they are actually just stuck. So there are no intermolecular bonds keeping the polymers togheter? they are just tangled togheter? $\endgroup$ – ward Oct 13 '15 at 18:48
  • $\begingroup$ I think so. More precisely, it is not important whether there is any specific bonding or not. $\endgroup$ – Ivan Neretin Oct 13 '15 at 19:15

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