流场环境下复杂囊泡的动力学行为

采用非平衡态分子动力学方法研究了二维复杂囊泡在剪切流中的动力学行为. 模拟发现了复杂囊泡经典的翻滚(tumbling)、摇摆(trembling)和坦克履(tank-treading)行为, 还观察到由坦克履行为向平动行为(translating)的转变. 囊泡的平动行为与剪切率大小、复杂囊泡的形状密切相关. 当大囊泡均匀嫁接较多数目的小囊泡后, 其平动方式消失. 该研究有益于加深对囊泡在剪切流场中复杂性行为的理解.     

Microdomain morphology of cylinder-forming diblock copolymers under spherical shell confinement

The topic of self-assembly of cylinder-forming diblock copolymers(DBCPs) under spherical shell confinement in different surface fields is explored using real-space self-consistent field theory calculations(SCFT).Using this approach we observed various microstructures of cylinder-forming DBCPs at different confinement dimensions and surface fields.From detailed searching for the microdomain morphologies,an obvious conclusion is that the interactions between the confinement surface and the polymers have a great effect on the self-assembly.Most of the microstructures are unique and not reported in bulk or under planar and cylindrical confinements.     

Surface-field-induced effects on morphologies of lamella-forming diblock copolymers in nanorod arrays

The surface-induced effect on the morphologies of lamella-forming diblock copolymers in nanorod arrays is studied by using the self-consistent field theory.In the simulation study,a rich variety of novel morphologies are observed by variations in the strength of the surface field for the diblock copolymers.Different surface-field-induced effects are examined for the diblock copolymers in the arrays with distinct preferential surfaces.It is observed that the majority-block preferential surfaces have more obvious induced effects than those of minority-block preferential surfaces.The strong surface fields exhibit different behaviours from those observed in the weak surface fields,by which the morphologies possess cylindrical symmetries.Results from this research deepen the knowledge of surface-induced effects in a confinement system,which may aid the fabrication of polymer-based nanomaterials.     

Effective transport of passive particles induced by chiral-active particles in microchannel

Transport of passive particles induced by chiral-active particles in microchannel is investigated by using the overdamped Langevin dynamics simulation in a two-dimensional model system. Due to the chirality of active particles and special structure of microchannel, effective ratchet transport of passive particles is achieved. Effective transport of passive particles depends on the width of microchannel(d), the density(ρ), and the angular velocity(ω) of chiral-active particles.There exist optimal parameters for d and ω at which the transport efficiency for passive particles takes its maximal value.This investigation can help us understand the necessity of active motion for living systems to maintain a number of vital processes such as materials transport inside cells and the foraging dynamics of mobile organisms.     

拉伸分子动力学方法研究高分子单链的吸附现象

采用拉伸分子动力学方法研究聚乙烯单链从一个强吸附表面被拉伸的动力学过程.当聚乙烯单链被拉伸时,从理想弹簧测量到的平均力与形变的曲线上出现了一个力的平台,这与实验结果非常一致.在研究这个平台力与拉伸速度的关系时发现,当速度v<0.001 nm/ps时,不随速度的变化而变化;当速度v>0.001 nm/ps时,随着拉伸速度的增加而迅速上升,这表明拉伸速度0.001 nm/ps是平衡态拉伸和非平衡态拉伸的临界点,并与链长无关.按顺序拉伸和释放这条链,观察到有趣的力回滞现象,并与实验结果进行了比较.     

球状蛋白质分子中氨基酸紧密接触对性质的研究

采用CSU软件 (Contactsofstructuralunits) ,对 61种球状蛋白质分子中氨基酸紧密接触对 (Residue residuecontact)进行了研究 .重点研究了不同氨基酸在形成远程紧密接触对 (Long rangecontact)和近程紧密接触对 (Short rangecontact)时的不同能力 .发现氨基酸Leu,Val,Ile,Met,Phe,Tyr,Cys,Trp(疏性氨基酸 ,H)比较容易形成远程紧密接触对 ,氨基酸Glu,Gln ,Asp ,Asn,Lys,Ser,Arg,Pro(亲水氨基酸 ,P)比较难形成远程紧密接触对 ,而氨基酸Ala,Gly,Thr,His(中性氨基酸 ,N)在形成远程紧密接触对时能力一般 .它们平均每个氨基酸可形成 6 0 3 ,3 64和 4 43个远程紧密接触对 .同时它们在形成近程紧密接触对时能力非常接近 ,平均每个氨基酸可形成的近程紧密接触对数目在 2 3 4～ 2 85变化 ,差别非常小 .亲水氨基酸 (P) ,中性氨基酸 (N)和疏水性氨基酸 (H)在蛋白质分子结构稳定性上起着不同的作用     

三级相互作用对聚亚甲基链末端距四次矩的影响

本文用三级相互作用近似理论导出了高分子链末端距的四次矩的计算公式。计算聚亚甲基链的末端距四次矩,并同二级相互作用的结果进行了比较。对于聚亚甲基链,三级相互作用近似的四次矩小于二级相互作用近似的四次矩。     

三维吸附紧密高分子单链的力学性质研究

采用PERM(pruned-enriched Rosenbluth method)算法,研究了吸附在界面附近的紧密高分子链力学行为.发现当界面的吸附能比较大时,紧密高分子链从紧贴于吸附界面到逐渐远离的过程中,其外形会经历4种典型的变化.同时紧密高分子链的尺寸大小如/N、xy/N、z/N,形状参数<δ*>,热力学性质如每个键的平均自由能A/N,平均相互作用能/N等,甚至所受外力的大小都会同时做出相应的变化,其出现变化的位置也一致.特别是随着紧密高分子链离开吸附界面的过程中,作用于高分子链上的外力明显出现几个力学平台,这与实验得到的结果完全一致.同时还研究了弱吸附能的情况,在这种情况下实验是很难进行的.     

聚苯乙烯链规整度与特性粘数的理论研究

应用构象 构型统计理论和旋转异构态模型 ,考虑大侧基对高分子链构型的影响 ,建立高分子溶液特性粘数与链无规程度的关系 ,并应用于大分子量的聚苯乙烯溶液的特性粘数的计算 ,得到特性粘数与全同、间同和无规链分子量的关系 ,并与实验结果进行比较 ,结果较为满意     

受限于平行板中高分子刷/磁性纳米粒子体系的构象性质研究

采用蒙特卡洛模拟方法研究了在外磁场作用下磁性纳米粒子/高分子刷组成的共混体系的统计构象性质.共混体系受限于两平行板之间,高分子刷—端随机嫁接在乎行板上,另一端自由生长,高分子刷与高分子刷之间以及磁性纳米粒子与磁性纳米粒子之间存在相互排斥作用,而高分子刷和磁性纳米粒子之间存在相互吸引作用,所施加的磁场方向与两平行板垂直....