A polymeric compound is disclosed herein, having the general formula I: wherein m, n, X, Y, Z and L are as defined herein. Further disclosed herein are lipid bilayers comprising at least one bilayer-forming lipid and the aforementioned polymeric compound, and liposomes comprising such a bilayer, as well as methods, uses and compositions utilizing such bilayers and/or liposomes for reducing a friction coefficient of a surface and/or for inhibiting biofilm formation.