I've never had a memory foam mattress but have used a m.f. mattress topper. It smelled funny, too. I can't stand that chemical smell & can't imagine it's at all 'good' for us?!
I quit using it alltogether (it really wasn't that great of a difference anyway).
But I would suggest doing what 1st poster mentioned, but also try some lavendar in sache's within the mattress cover(s) (lavendar is great for relaxation/easing tension & if u get it fresh from the garden, it's a lovely soft scent. But use whatever scent u prefer, just don't get any that smell really strong or that may be bothersome, too!)
May, try using a 'plastic' cover under the rest of the bedding. They make them really nice now, no smells, noise, etc. That may hold the smell down just fine. Then put on a padded mattress cover, maybe even 2 of them, to see if that helps to diffuse the smell further.
If you can't get anything to work...take it back!! Get a regular mattress & add some padding that's natural for that extra softness.