DSPE-PEG 2000 is a lipid-polymer conjugate used to form stable micelles for drug delivery, with the PEG head group enhancing biocompatibility and circulation time. The micelles undergo a phase transition at 12°C, from a glassy to a fluid phase, affecting stability and monomer desorption rates. The size of the PEG chain and lipid tail influence the micelles transition temperature and overall behavior in drug delivery systems.