[sharbeldam]

Is there a simple rule to know if the product polymer from monomers will be thermoplastic or not?

The polymerization that are in the syllabus
1) Double bond addition
2) conjugated double bond addition
3) Diamine with diacid
4) diol with diacid
5) alcohol with acid (in same molecule)

...etc.
So according to what i read, when it's one double bond addition, usually it will be straight chain (thermoplastic).
is there a rule to know? or just drawing the [Polymer]n and judging by how it looks?

Thanks.

[wildfyr]

Thermoset or thermoplastic isn't differentiated by the functional groups of the polymer per se, but rather its macroscopic phase behavior. A thermoset goes from liquid to solid irreversibly. Often heat is what causes this, but newer technologies take advantage of UV irradiation, inclusion of catalysts, or other triggering factors. Once solidied, that is it for a thermoset, its shape cannot be modified without damaging it.

A thermoplastic can be cycled between a solid at temps below the melting point and a liquid at above the melting point many times. Its shape in the solid can therefor be modified just by heating and pouring into another mould.

What causes something to be a thermoset structurally usually has to do with the presence of reactive groups pendant to the main polymer backbone. A good example is that PDMS with a small amount of pendant Si-H groups and another PDMS with small amount of vinyl groups will be combined together. They exist as a mixture of liquid polymers, but when a bit of Pt catalyst is added, the mixture will crosslink and set into a hard shape.

[sharbeldam]

Thank you for the explanation.
So it isn't accurate to ask that question? it is repeated in the exams every year. they give the students two monomers  and they ask if the resulting polymer becomes thermoplastic or themoset. after you draw the product [XXXXXXX]n, is there a way to detemine what it is? if it look straight

For instance please look at the picture attached, the first and second one results in thermoplastic polymer (I guess because it's straight chain?

But for instance what about the third one, how would i know what kind of a polymer would it form?

I tried to write the reapeating unit, and it had one bond up, one bond now (after additions), it does look thermoset, or am i wrong

[wildfyr]

That compound is 2-Methyl-2-pentenoic acid, which is generally a small flavor/smell molecule, not a monomer. I personally think it's kind of a crappy question. I'm a fully qualified PhD polymer chemist and I am not 100% sure whether the resultant polymer would be a thermoset or a thermoplastic. I'm guessing a thermoset... but more because of context than any actual chemical insight. There is not any kind of trend whether condensation or free radical polymers are more likely to be thermosets or thermoplastics.

Only thing I can say is that polymers with pendant carboxylic acids usually degrade before they melt. A bit subtle for students to know, and hardly a rule.

Ask your professor for the reasoning on this question perhaps.

[Enthalpy]

As a user of polymers, I've haven't seen any relationship neither.

PA6,6 and aramide have linear chains. One the thermoplastic, the other not. Worse: both are polyamides.

Some thermoplastic elastomers are (a bit) cross-linked, while more cross-linked polymers are thermosetting.