Provided herein is a polymer comprising greater than or equal to about 70 wt % units derived from ethylene, less than or equal to about 30 wt % units derived from propylene, and less than about 5 wt % of units derived from C4-C20 alpha-olefins, and having the following properties: crystallinity derived from ethylene; a heat of fusion of about 20 to about 85 J/g; a polydispersity index (Mw/Mn) of less than about 2.5; a reactivity ratio of about 0.5 to about 1.5; a proportion of inversely inserted propylene units based on 2, 1 insertion of propylene monomer in all propylene insertions, as measured by 13C NMR of less than 0.5 wt %; and a branching index greater than about 0.5