Three new amphiphilic polyphosphates containing two long hydrophobic side chains were synthesized by the polycondensation of pentaerythrite di fatty acid esters with β bromoethyl dichorophosphate in benzene

and then by quaterisation with trimethyl amine.The results of IR

1H-NMR spectra and elemental analyses indicate that all the polymers have the expected chemical structures.Average molecular weight of polymers prior to quaterisation was determined by VPO method.The nitrogen content from elemental anyalyese data showed that the polymers containing 46%～49% of quaternary ammonium side chains.All quaternarized polyphosphates were used to prepare liposome by using reverse phase evaporation method.All of them could form large unilamellar liposome.The diameter of liposome is 2～6 μm.Encapsulation ratio of liposome to 5-fluorouracil was also determined.