Based on the Compass force field

the relationship between microstructure and macro-properties of carbon dioxide/propylene oxide/γ-butyrolactone tricopolymer (PPCG) was investigated by the`Materials Studio' simulation successfully.The results of simulation show that the molecular chains of PPCG are of flexible.Degradable carbonic and carboxylic ester groups were distributed outside the PPCG cell.Furthermore the structure of micro-phase separation was observed in PPCG cell.The reciprocity between PPCG and caffeine molecule was also simulated and calculated.It was found that the caffeine molecule was selectively distributed in CO2 habitat

but never in γ-butyrolactone (GBL) habitat.So the structure of micro-phase separation of PPCG can be applied in achieving the self-assembly of drug molecules

and the conclusion offers a theoretical base for the self-assemble behavior of drug molecule in this kind polymer carrier.The results of molecular simulation not only verified the experimental conclusions

but also showed a clear description about the relationships between molecular structure and macroscopic properties of PPCG.Moreover

it offered the theoretical base for further studying the reciprocity between carriers and drug molecules.