Ethylene based copolymer compositions as viscosity modifiers and methods for making them

A method for making a polymer composition comprising the steps of:

• (a) combining (i) a first ethylene-based copolymer having a weight percent of ethylene-derived units based on a weight of the polymeric composition (EA) ranging from about 47 wt % to about 52 wt % and a weight-average molecular weight (MwA) of from 60,000 to 130,000 with (ii) a second ethylene-based copolymer having a weight percent of ethylene-derived units based on the weight of the polymeric composition (EB) ranging from about 65 wt % to about 85 wt % and a weight-average molecular weight (MwB) of from 70,000 to less than 130,000 less than 130,000, wherein the molecular weight distribution (MWD) of the first ethylene-based copolymer is less than 2.4 and the MWD of the second ethylene-based copolymer is less than 2.4;
• and
• (b) forming the composition, wherein the composition comprises the first ethylene-based copolymer in an amount of at least 33 wt %, based on the combined weight of the first and second ethylene-based copolymers, wherein the polymeric composition comprises from about 51.6 wt % to about 62.7 wt % ethylene-derived units, based on the weight of the polymeric composition, and wherein the polymeric composition has a weight average molecular weight (Mw) of from about 77,000 to about 88,000 and a MWD of from about 1.9 to about 2.15.