[cclar56]

What are the intermolecular forces acting on vulcanised cis-polyisoprene and vulcanised neoprene, and where are these forces located on both polymers? Both polymers are vulcanised using sulphur.

[Borek]

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[cclar56]

I hope this classifies as an attempt. I have found that there is no polar group in polyisoprene, which means that the intermolecular forces are weak van der wall forces of attraction, also known as dipole-dipole forces (http://www.chemistrylearning.com/rubber/). I can't remember where I found it, but I am pretty sure that the intermolecular forces acting on vulcanised neoprene are the same as those acting on vulcanised polyisoprene. From this I looked up dipole-dipole forces and found that they are attractive forces that act between the positive end of one polar molecule and the negative end of another polar molecule (http://www.chem.purdue.edu/gchelp/liquids/dipdip.html). This is where I get stuck. I have diagrams of vulcanised polyisoprene and vulcanised neoprene, but I am not sure where the intermolecular forces occur.

[Enthalpy]

The aim of vulcanization is to create new chemical bonds between the macromolecules.

[cclar56]

So what does that mean exactly? Are their no intermolecular forces because the polymers are vulcanised? Am I on the right track in my attempt of did I veer off course somewhere?

[Corribus]

So what does that mean exactly? Are their no intermolecular forces because the polymers are vulcanised? Am I on the right track in my attempt of did I veer off course somewhere?

Vulcanization is a form of polymer crosslinking - forming covalent bonds between individual polymer molecules.  There will still be "intermolecular" forces (van der Waals, London dispersion, etc.) but the newly formed covalent crosslinks are much stronger and so dominate macroscale properties,

"Intermolecular" has ambiguous meaning with polymers anyway, because they are so big and have many distal parts. Two ends of a single polymer chain can interact with each other by van der Waals forces - are they intermolecular or better described as intramolecular?

[cclar56]

Ok. It is part of my assignment to show where the intermolecular forces are on the molecules, so am I better of saying that due to the sulphur cross-links any intermolecular bonds that are in the molecule are considered redundant as intermolecular forces are so much weaker than intramolecular forces?

[Corribus]

Honestly, the only way this question makes sense to me is that it's asking for what the products of vulcanization look like -where do the sulfurs go. However, calling them "intermolecular forces" seems strange to me.