Polymer, separator, and related secondary battery and electric apparatus

A polymer, a separator, and a related secondary battery and electric apparatus are described. The polymer includes a first structural unit, a second structural unit, and a third structural unit; where the first structural unit includes a structural unit represented by formula (I), and in formula (I), Rincludes one or more of hydrogen atom and substituted or unsubstituted C1-C5 alkyl, and Rincludes one or more of substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, and substituted or unsubstituted C1-C20 hydroxyalkyl; the second structural unit includes a structural unit represented by formula (II), and in formula (II), Rincludes one or more of hydrogen atom and substituted or unsubstituted C1-C5 alkyl; and the third structural unit includes a structural unit represented by formula (III). The units in the polymer can synergistically improve the adhesion, stability, swelling resistance, and thermal stability of the polymer.