Computer simulation studies of the influence of side alkyl chain on glass transition behavior of car

• 作 者: Chunyang Yu Li Ma Wei Huang Yongfeng Zhou Jingui Qin Deyue Yan
• 机 构: State Key Laboratory of Metal Matrix Composites,School of Chemistry & Chemical Engineering,Shanghai
• 出 处: Science China(Chemistry)
• 发表日期: 2017年03期
• 关键词: relaxation alkyl carbazole conformational chains Arrhenius agree rotational barr

In this work,all-atom molecular dynamics simulations were employed to study the influence of the side alkyl chain on glass transition behavior of several carbazole trimers(CT) in a temperature range from 423 to 183 K.The glass transition temperatures were obtained from the break in the slope of the volume-temperature curves and found to agree with the experimental values.The short time dynamics of four CT molecules were probed by usingvelocity autocorrelation functions and mean-square displacements.The current studies showed that the dynamics of CT systems can be easily interpreted through the cage effect.Furthermore,the investigation of the torsional autocorrelation function and P_(2-state)/P_(3-state) functions showed that the rotational barriers of side chains can slow down the conformational relaxation and lead to stronger temperature dependence of conformational relaxation.The relaxation time,characteristic time of P_(2-state)(t) and P_(3-state)(t) functions were all found to have Arrhenius-type temperature dependence.

In this work, all-atom molecular dynamics simulations were employed to study the influence of the side alkyl chain on glass transition behavior of several carbazole trimers (CT) in a temperature range from 423 to 183 K. The glass transition temperatures were obtained from the break in the slope of the volume-temperature curves and found to agree with the experimental values. The short time dynamics of four CT molecules were probed by usingvelocity autocorrelation functions and mean-square displacements. The current studies showed that the dynamics of CT systems can be easily interpreted through the cage effect .Furthermore, the investigation of the torsional autocorrelation function and P_ (2-state) / P_ (3-state) functions showed that the rotational barriers of side chains can slow down the conformational relaxation and lead to to temperature dependence of conformational relaxation. The relaxation time, characteristic time of P_ (2-state) (t) and P_ (3-state) (t) functions were all found to have Arrhenius-type temperature dependence.