I have problem making this plunkr (select2 + angulat-ui) work.
http://plnkr.co/edit/NkdWUO?p=preview
In local setup, I get the select2 work, but I cannot set
add method container css in your script like this :
$("#your_select_id").select2({ containerCss : {"display":"block"} });
it will set your select's width same as width your div.