The only ones I've ever had were the plastic wadcutters Speer used to make for firing by primer-only through a revolver. Polymers are, in general, too low in density to fly very far or penetrate very well.
If, instead, you meant polymer-tipped or polymer-coated (H&N pistol bullets, for example) or lead that has a polymer powder coat application, you'll need to specify it.
If you are looking at the PolyCase bullets, they have copper for mass, bonded in a polymer. Their GRX design takes advantage of the fact a mold is easily made to give you any shape. Will it actually do anything a flat meplat or truncated cone won't do? I'd have to be convinced. A bullet only completes a revolution once in multiple bullet lengths of travel. It's not like a spinning blade being slowly pressed into something, so the idea appears to me to be a large percent hype. Their .380 bullet only weighs 56 grains, so the density is about half that of a same dimension conventional bullet. This may create stability problems in slower twist barrels. I don't have enough information to tell.