what to do if you need to return to work and your baby refuses to take a bottle
Before returning to work, offer your baby the bottle prior to nursing, so the idea of the bottle isn't foreign. Even if your baby refuses the bottle now, at least you know it's not a totally foreign concept when you're at work.
Warn whoever your daycare provider is that the first few days may be rough. That being said however, and as harsh as it sounds, when he/she's hungry enough, he/she'll take the bottle. And after a few days it should be totally fine. Babies are often (or so I've read) much more willing to take a bottle from someone who's not mom, since they can smell your milk when you're holding them. So if you've been the only one trying to get him to bottle feed and it's not working, it may be a much easier thing when someone else is doing it.
That first day/week back at work may be rough. Hang in there! I'm sure your baby will get the bottle figured out in now time.