A unimodal polymer having a melt index of from about 0.5 g/10 min to about 4 g/10 min, a density of equal to or greater than about 0.945 g/cc which when formed into a film displays a moisture vapor transmission rate of less than about 0.55 g-mil/100 in2 in 24 hours as determined in accordance with ASTM F 1249. A unimodal polymer having a melt index of from about 0.5 g/10 min to about 4 g/10 min, a density of equal to or greater than about 0.945 g/cc which when formed into a film displays a moisture vapor transmission rate of less than about 0.44 g-mil/100 in2 in 24 hours as determined in accordance with ASTM F 1249.