Addition polymerization mechanism -Help PLEASE

Watch
JacobBob
Badges: 10
Rep:
?
#1
Report Thread starter 1 year ago
#1
Just to make sure I understand this
Should the monomer that undergoes homolytic fission in initiation be made of another molecule bonded to itself ? I reckon there's a better wording but my brain is dead atm.
And if not, then how do I decide where the molecule breaks ?


Also, in propagation, is the first attack always with ethene ?
0
reply
CuriosityYay
Badges: 19
Rep:
?
#2
Report 1 year ago
#2
There is addition polymerisation where there is one monomer with a double bond that breaks to form a giant thread-like molecule.

There is free radical propagation where there is an initiation step like chlorine molecule forming two chlorine radicals that destroy the ozone layer.

Hope that helps
0
reply
JacobBob
Badges: 10
Rep:
?
#3
Report Thread starter 1 year ago
#3
(Original post by CuriosityYay)
There is addition polymerisation where there is one monomer with a double bond that breaks to form a giant thread-like molecule.

There is free radical propagation where there is an initiation step like chlorine molecule forming two chlorine radicals that destroy the ozone layer.

Hope that helps
Name:  160.jpg
Views: 60
Size:  37.2 KB From this page I understood that addition polymerisation works with the free radical substitution mechanism.
I am asking about that,
Attached files
0
reply
charco
Badges: 17
Rep:
?
#4
Report 1 year ago
#4
(Original post by JacobBob)
Name:  160.jpg
Views: 60
Size:  37.2 KB From this page I understood that addition polymerisation works with the free radical substitution mechanism.
I am asking about that,
Addition polymerisation mechanism may be free radical or ionic, depending on the conditions.

The original conditions used a free radical initiator catalyst. The actual discovery was caused by oxygen impurity in an ethene pipe under pressure, oxygen is a diradical molecule, which in this case initiated the reaction.

The problem with free radical mechanisms is that they are not easy to control in terms of the products. Polymers made using a free radical mechanism tend to be atactic.

Nowadays, addition polymerisation uses Zeigler-Natta catalysts (trialkyl aluminium compounds and titanium trichloride/ tetrachloride as welll as many other variations). The mechanism of this polymerisation is ionic and the products are far easier to control in terms of side chains to the polymeric chain. This allows the formation of syntactic polymers which are more crystalline.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Should there be a new university admissions system that ditches predicted grades?

No, I think predicted grades should still be used to make offers (699)
33.88%
Yes, I like the idea of applying to uni after I received my grades (PQA) (880)
42.66%
Yes, I like the idea of receiving offers only after I receive my grades (PQO) (392)
19%
I think there is a better option than the ones suggested (let us know in the thread!) (92)
4.46%

Watched Threads

View All
Latest
My Feed