1. An elastic, ethylene-based quaterpolymer comprising:
55-93.9 mol % of an ethylene unit;
3-40 mol % of a C4-6 ?-olefin unit;
3-40 mol % of a C8-12 ?-olefin unit; and
0.1-5 mol % of a functional unit derived from at least one styrene-based monomer,
the ethylene-based quaterpolymer having a weight-average molecular weight of 50,000-300,000 and a glass transition temperature
between ?40Â° C. and ?80Â° C.