The glass transition behavior of chitosan was studied through molecular dynamics (MD)simulation with the range of temperatures from 343 K to 543 K

and the glass transition temperature Tg of chitosan was obtained.The molecular mechanics force field used in this study was COMPASS(condensed-phase optimized molecular potentials for atomistic simulation studies)which has been validated for chitosan in some previous communications.Under the COMPASS force field and in the NPT ensemble

the specific volumes

radii of gyration and energies of chitosan at different temperatures were calculated.The results showed that the specific volume

radius of gyration and internal energy of chitosan regularly changed along with the change of temperature

and the transition began at the Tg point.The calculated Tg

especially the value obtained from the slop transition of the radius of gyration vs temperature curve

was in good agreement with the experimental results.Therefore

the radius of gyration has great influence on glass transition

and the MD simulation method is a useful tool to predict the glass transition temperature of polymer.