What are the essential conditions for polymerization to take place?

[toothpaste666]

Homework Statement

What three conditions or ingredients are necessary for polymerization to occur?

The Attempt at a Solution

I know that carbon is necessary because it is the only element that can form complex molecules readily in nature. But when i try to research this problem it seems there are many types of polymerization that can occur (addition, condensation, step growth etc) . I am having a hard time figuring out what is absolutely necessary to all of them since they seem to occur in different ways. I think light is necessary for energy for the reactions to occur but I am not entirely sure. If I had to guess an answer I would say carbon, light and water

 

[Bystander]

I would say carbon, light and water

Polysilanes, polysulfanes, polythiazenes, come to mind --- "carbon" is then not necessary. Light? At the dentist's UV is used for setting polyacrylates, but it's hardly a universal requirement. Water? Polymerizations occur in a wide variety of solvents, and without solvents.

Is the question exactly as you've presented it?

 

[Borek]

I suppose they want you to address mechanics of the polymerization process - it has to start, it has to continue.

 

[toothpaste666]

Wow I was completely off. I went to the index of my textbook and it didn't even have polymerization. I'm afraid it may have been talked about in a lecture I missed.

But Yeah that is the question word for word. I looked up polymerization but I haven't found anything about the necessary conditions for it to occur

 

[Bystander]

One: what does a reactant in a polymerization reaction have to have? An absolute "gotta" condition. See if we can come up with some set of necessary conditions for you.

 

[toothpaste666]

It has to be able to form strong bonds easily like carbon and silicon

 

[Borek]

I told you - try to think in terms of the mechanism. Not in terms of specific bonds, but in terms of molecules and the created chain, that's what is common for all polymers.

 

[toothpaste666]

this is for an astronomy class so I don't know much about polymers, but if i remember right from chemistry I think the atoms need to be able to bond to up 4 other atoms at once.

 

[Borek]

No, you are still on the wrong track, you have fixed yourself on the bonding between atoms, and that's not what you need here.

Hint: every polymer is made of monomers, doesn't matter what they are and how they are bonded between them. Once two monomer molecules combine they produce the smallest possible polymer. However they are still able to react further with other monomers. This is what the mechanism is based on.

 

[Bystander]

4 other atoms

?

you have fixed yourself on the bonding between atoms

Think about the language; chemists speak of polymer chains. How do chains link together?

 

[toothpaste666]

From reading about this I have gathered that the chains link together by dehydration synthesis. The chains are formed by individual monomers so I guess you need several monomers and you need water to be removed from them so they can link together. Also I think polymers are usually repeated patterns of the same monomers that link in the same way

 

[Bystander]

For condensation polymerization reactions

the chains link together by dehydration

but, not all polymerizations proceed by condensation reactions.

 

[toothpaste666]

hmm i am lost. I can't seem to find much. Does it have to do with electrons or free radicals?

 

[Borek]

polymers are usually repeated patterns of the same monomers that link in the same way

That's the correct direction!

 

[toothpaste666]

so you need several of the same monomer that is one condition. this monomer has to be able to break one of its bonds and replace with a similarly broken bond of the other monomer. this process has to be able to repeat. I am not quite sure what conditions are universal for all monomers to be able to do this. I am guessing oxygen is important because that dissolves bonds?

 

[Borek]

Don't worry about bonds. You have already mentioned condensation, which is another kind of polymerization in which monomer doesn't have a bond that can be easily broken (I guess you are trying to describe radical polymerization of a compound with a double bond; yes that's one of the ways it can go, but it is not an universal property of all polymers).

But IMHO you are on the right track. You need monomers, and the process of combining them has to be repeatable (that is, molecule produced after the monomer is attached to the previous existing polymer, produced polymer is still capable of reacting with the next monomer).

 

[toothpaste666]

so you need monomers. for the process to be repeatable i think they need to be the same type of monomer? and for any reaction you need an energy source? or am i thinking too simple/general?

 

[epenguin]

this is for an astronomy class so I don't know much about polymers, but if i remember right from chemistry I think the atoms need to be able to bond to up 4 other atoms at once.

Not stellar astronomy then?