So instead they form these lipid bilayer. So phospholipids and glycolipids readily form bilayer structures and not my cells. This is because the larger non polar tails of these lipids is too large to fit into the limited space of the MiCell. So what exactly allows these two structures to form spontaneously? So, as we said a moment ago, it's the hydrophobic effect that is the driving force in the formation of the cell membrane, the lipid bilayer and micelles. So the interaction of the hydrocarbon tails releases the water molecules from the nonpolar regions and this is energetically stabilizing, energetically favorable.