Is cotton and polyester on a jacket warm?

Can someone please tell me if these are two good materials for winter. I prefer wool for a winter jacket, however, I'm looking at purchasing a parka, so for everything, so that I don't have to wear my wool coat for informal occassions (like going for groceries or just chilling out with friends). Now, on a... show more Can someone please tell me if these are two good materials for winter. I prefer wool for a winter jacket, however, I'm looking at purchasing a parka, so for everything, so that I don't have to wear my wool coat for informal occassions (like going for groceries or just chilling out with friends).
Now, on a parka, having cotton and polyster good? the winters in australia aren't too cold.

Also, what is 'shell' on a jacket? I'm looking at parkas and they are saying 'shell' with the material (like cotton or polyster) and i'm just wondering what exactly is that?
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