A separator, a battery cell, a battery, and an electric device. The separator comprises a liquid retention polymer, and the separator satisfies the following formula: (m.sub.2M)/(m.sub.1M)25%, wherein M represents the mass of the electrolyte not absorbed by the separator, and the unit thereof is g; m.sub.1 represents the mass of the separator weighed under an ambient pressure after having been immersed in the electrolyte for 2 h, and the unit thereof is g; and m.sub.2 represents the mass of the separator weighed under a pressure of 10,000 N in the ambient pressure after having been immersed in the electrolyte for 2 h, and the unit thereof is g.

Provided are a polymer including a first repeating unit represented by Formula 1 and a second repeating unit represented by Formula 2, a method of producing the same, a resist composition including the polymer, and a method of producing a pattern by using the resist composition:

##STR00001##

wherein, for descriptions of L.sub.11, a11, X.sub.11, c11, Y.sub.21, Y.sub.22, n21, L.sub.21, L.sub.22, a21, a22, R.sub.21, R.sub.22, X.sub.21, X.sub.22, c21, c22 and o21 in Formulae 1 and 2, reference should be made to the specification.