The ^(13)C T_(1s) of --CH_3 side group in PPU/P (St-co-AA), AB-crosslinked polymers (i. e.ABCP) was studied by using high resolution solid state NMR. The rotation motion of --CH_3 sidegroup in PPU was analyzed by mean...The ^(13)C T_(1s) of --CH_3 side group in PPU/P (St-co-AA), AB-crosslinked polymers (i. e.ABCP) was studied by using high resolution solid state NMR. The rotation motion of --CH_3 sidegroup in PPU was analyzed by means of the average spectral density functions of internal rota-tion. The results showed that the rotation of the --CH_3 side group is related closely to the com-patibility between the two components. The compatibility was studied by analyzing the protonspin-lattice relaxation in rotating frame, spin-spin relaxation and spin-diffusion. The resultsshowed that the hydrogen bonds between the components play a major role in determining thecompatibility. Through spin diffusion studying, the soft phase domain size was calculated. Bystudying proton spin-spin relaxation, the content of each component in each phase and that ofeach phase in the samples can be obtained. The result shows that the content of interphase is related closely to the compatibility.展开更多
The molecular motion in polyepichlorohydrin (PEPCH), in solution and bulk, was studied by high resolution NMR by means of line width, spin-lattice relaxation time T_1 and nuclear Overhauser effect NOE. The results sho...The molecular motion in polyepichlorohydrin (PEPCH), in solution and bulk, was studied by high resolution NMR by means of line width, spin-lattice relaxation time T_1 and nuclear Overhauser effect NOE. The results show that the VJGM model can describe the main chain motion of PEPCH in solution perfectly. In bulk state, the relationship between the line width and the temperature is consistent with WLF equation, but that between the high frequency molecular motion correlation time (in T_1 scale ) and temperature is consistent with Arrhenius equation. The motion parameters of PEPCH in both states were calculated. The internal rotation motion of side—CH_2Cl group was analyzed by using equal three-site jump and diffusion internal rotation model in both states.展开更多
In this paper, the fully anisotropicoverall tumbling motions and side groups internal rotation of ocotillol-type saponins separated from the leaves of Panax Quidquefolium L. are investigated by <sup>13</sup&g...In this paper, the fully anisotropicoverall tumbling motions and side groups internal rotation of ocotillol-type saponins separated from the leaves of Panax Quidquefolium L. are investigated by <sup>13</sup>C nuclear magnetic relaxation. The fully anisotropic overall tumbling motion model with methyl conformation jumps internal rotation among three equivalent sites is presented, and the spectral density function of this model is derived. The rotation rates for overall tumbling motions to ocotillol-type saponins （OTS） are computed by Woessner’s fully anisotropic overall tumbling motion model, and the internal rotation rate and barrier for side groups in OTS are calculated using free diffusion internal rotation model, restriction diffusion internal rotation model and conformation jumps internal rotation model, respectively.展开更多
Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of at...Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mecha- nisms underlying the strain rate effects.展开更多
The collective motion of rounded squares with different comer-roundness ζ is studied by molecular dynamlcs （MD） simulation in this work. Three types of translational collective motion pattern are observed, includin...The collective motion of rounded squares with different comer-roundness ζ is studied by molecular dynamlcs （MD） simulation in this work. Three types of translational collective motion pattern are observed, including＇, gliding, hopping and a mixture of gliding and hopping. Quantitatively, the dynamics of each observed ordered phase is characterized by both mean square displacement and van Hove functions for both translation and rotation. The effect of corner-roundness on the dynamics is further studied by comparing the dynamics of the rhombic crystal phases folmed by different comer-.rounded particles at a same surface fraction. The results show that as ζ increases from 0.286 to 0.667, the translational collective motion of particles changes from a gliding-dominant pattern to a hopping-dominant patte;n, whereas the rotational motion pattern is hopping-like and does not change in its type, but the rotational hopping becomes much more frequent as increases （i.e., as particles become more rounded）. A simple geometrical model is proposed to explain the trend of gliding motion observed in MD simulations.展开更多
合成了3种可聚合的1,8-萘酰亚胺衍生物,并研究了其在二甲基亚砜(DMSO)溶液中的光物理性质.这些化合物表现出的光物理性质与其电子环境有关.通过溶胶-凝胶法制备了可聚合1,8-萘酰亚胺衍生物与硅氧烷的共聚物.尽管3种萘酰亚胺衍生物C-4位...合成了3种可聚合的1,8-萘酰亚胺衍生物,并研究了其在二甲基亚砜(DMSO)溶液中的光物理性质.这些化合物表现出的光物理性质与其电子环境有关.通过溶胶-凝胶法制备了可聚合1,8-萘酰亚胺衍生物与硅氧烷的共聚物.尽管3种萘酰亚胺衍生物C-4位的取代基不同,但在3-氨丙基三乙氧基硅烷(APTES)固凝胶中摩尔分数为0.06%时荧光强度均最大.利用29Si MAS NMR对合成材料进行了表征,结果表明,硅氧烷的缩聚程度影响材料的荧光强度,说明材料中荧光单元的分子运动对材料的荧光性能有重要影响.展开更多
基金The project was supported by the National Natural Science Foundation of China
文摘The ^(13)C T_(1s) of --CH_3 side group in PPU/P (St-co-AA), AB-crosslinked polymers (i. e.ABCP) was studied by using high resolution solid state NMR. The rotation motion of --CH_3 sidegroup in PPU was analyzed by means of the average spectral density functions of internal rota-tion. The results showed that the rotation of the --CH_3 side group is related closely to the com-patibility between the two components. The compatibility was studied by analyzing the protonspin-lattice relaxation in rotating frame, spin-spin relaxation and spin-diffusion. The resultsshowed that the hydrogen bonds between the components play a major role in determining thecompatibility. Through spin diffusion studying, the soft phase domain size was calculated. Bystudying proton spin-spin relaxation, the content of each component in each phase and that ofeach phase in the samples can be obtained. The result shows that the content of interphase is related closely to the compatibility.
基金The project was supported by the National Natural Science Foundation of China
文摘The molecular motion in polyepichlorohydrin (PEPCH), in solution and bulk, was studied by high resolution NMR by means of line width, spin-lattice relaxation time T_1 and nuclear Overhauser effect NOE. The results show that the VJGM model can describe the main chain motion of PEPCH in solution perfectly. In bulk state, the relationship between the line width and the temperature is consistent with WLF equation, but that between the high frequency molecular motion correlation time (in T_1 scale ) and temperature is consistent with Arrhenius equation. The motion parameters of PEPCH in both states were calculated. The internal rotation motion of side—CH_2Cl group was analyzed by using equal three-site jump and diffusion internal rotation model in both states.
基金Project supported by the National Natural Science Foundation of China and the State Key Laboratory of Applied Organic Chemistry, Lanzhou University.
文摘In this paper, the fully anisotropicoverall tumbling motions and side groups internal rotation of ocotillol-type saponins separated from the leaves of Panax Quidquefolium L. are investigated by <sup>13</sup>C nuclear magnetic relaxation. The fully anisotropic overall tumbling motion model with methyl conformation jumps internal rotation among three equivalent sites is presented, and the spectral density function of this model is derived. The rotation rates for overall tumbling motions to ocotillol-type saponins （OTS） are computed by Woessner’s fully anisotropic overall tumbling motion model, and the internal rotation rate and barrier for side groups in OTS are calculated using free diffusion internal rotation model, restriction diffusion internal rotation model and conformation jumps internal rotation model, respectively.
基金supported by the National Basic Research Program of China (973 Program)(2012CB937500)the National Natural Science Foundation of China (11202212,10932011,11021262,11172024,11172305,and 11232013)
文摘Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mecha- nisms underlying the strain rate effects.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21573159 and 21621004)
文摘The collective motion of rounded squares with different comer-roundness ζ is studied by molecular dynamlcs （MD） simulation in this work. Three types of translational collective motion pattern are observed, including＇, gliding, hopping and a mixture of gliding and hopping. Quantitatively, the dynamics of each observed ordered phase is characterized by both mean square displacement and van Hove functions for both translation and rotation. The effect of corner-roundness on the dynamics is further studied by comparing the dynamics of the rhombic crystal phases folmed by different comer-.rounded particles at a same surface fraction. The results show that as ζ increases from 0.286 to 0.667, the translational collective motion of particles changes from a gliding-dominant pattern to a hopping-dominant patte;n, whereas the rotational motion pattern is hopping-like and does not change in its type, but the rotational hopping becomes much more frequent as increases （i.e., as particles become more rounded）. A simple geometrical model is proposed to explain the trend of gliding motion observed in MD simulations.
文摘合成了3种可聚合的1,8-萘酰亚胺衍生物,并研究了其在二甲基亚砜(DMSO)溶液中的光物理性质.这些化合物表现出的光物理性质与其电子环境有关.通过溶胶-凝胶法制备了可聚合1,8-萘酰亚胺衍生物与硅氧烷的共聚物.尽管3种萘酰亚胺衍生物C-4位的取代基不同,但在3-氨丙基三乙氧基硅烷(APTES)固凝胶中摩尔分数为0.06%时荧光强度均最大.利用29Si MAS NMR对合成材料进行了表征,结果表明,硅氧烷的缩聚程度影响材料的荧光强度,说明材料中荧光单元的分子运动对材料的荧光性能有重要影响.
