TECHNOLOGY FOCUS - POLYMERS - Preferred Membrane: The multilayer, microporous membrane, comprises: (a) a first layer containing a first polymer (10-45 wt.%) having melting point temperature (Tm) of 115-130 degrees C and weight average molecular weight (Mw) of 5 x 103 to 4 x 105, a polyethylene (55-90 wt.%) having an Mw of less than 1 x 106 and an amount of terminal unsaturation is less than 0.20 per 10000 carbon atoms; (b) second layer containing a polyethylene (70-98 wt.%) having Mw of less than 1 x 106 and a polyethylene (2-30 wt.%) having Mw of greater than or equal to 1 x 106; and (c) a third layer containing a second polymer (10-45 wt.%) having a Tm of 115-130 degrees C and an Mw of 5 x 103 to 4 x 105 and a polyethylene (55-90 wt.%) having an Mw of less than 1 x 106 and an amount of terminal unsaturation is less than 0.20 per 10000 carbon atoms, the second layer is located between the first and third layers. The membrane is a three-layer membrane, and where the polyethylenes in the first and third layers have the same weight average molecular weight and the same amount of terminal unsaturation. The membrane further comprises at least a third layer containing an ethylene/ alpha -olefin copolymer having a Tm of 121-125 degrees C and a polyethylene having an Mw of less than 1 x 106 and an amount of terminal unsaturation is less than 0.20 per 10000 carbon atoms. Preferred Components: The first polymer is an ethylene/ alpha -olefin copolymer having Tm of 121-125 degrees C. The polyethylene of the second layer has an Mw of les than 1 x 106 and an amount of terminal unsaturation is greater than or equal to 0.2 per 10000 carbon atoms. The polyethylene of the second layer has an amount of terminal unsaturation of less than 0.20 per 10000 carbon atoms. The polyethylene of the second layer has an Mw of less than 1 x 106 and an amount of terminal unsaturation is less than 0.12 per 10000 carbon atoms. The first layer includes a polyethylene having an Mw of less than 1 x 106 and an amount of terminal unsaturation is less than 0.20 per 10000 carbon atoms. The second layer is located between the first and third layers. The second layer has a thickness of 5-95% of the total thickness of the multilayer, microporous membrane. The polyethylenes in the first and/or third layers further comprise a polyethylene having an Mw of greater than or equal to 1 x 106. The polyethylenes in the first and second layers together have a total amount of terminal unsaturation of 0.009-0.032 per 10000 carbon atoms. The amount of terminal unsaturation of the polyethylenes of the first and third layers is less than or equal to 0.14 per 10000 carbon atoms and the polyethylene of the second layer has an Mw of less than 1 x 106 and an amount of terminal unsaturation is greater than or equal to 0.20 per 10000 carbon atoms. The total amount of polyethylene having an Mw of less than 1 x 106 and a terminal unsaturation amount of greater than or equal to 0.20 per 10000 carbon atoms of 3-17 wt.% based on the total weight of the multilayer, microporous membrane. EXAMPLE - No suitable example given.