高分子链在吸引表面的吸附、构象和动力学性质

发布时间：2018-05-14 10:19

  本文选题：高分子 + 吸附　； 参考：《浙江大学》2017年博士论文

【摘要】：高分子在表面的吸附是生物、物理和化学领域的重要课题,这归因于它的普遍性和巨大的潜在应用价值,如高分子粘合剂、胶体稳定化、高分子纳米复合材料、涂层和润滑、细菌内DNA的分离、病毒内DNA的包装和超疏水/超亲水材料。我们用Monte Carlo方法研究了高分子在吸引表面上的吸附、构象和动力学性质。主要的研究内容和结果如下:(1)高分子在均匀吸引表面上的吸附过程。在吸附过程中高分子链平行于表面的表观尺寸随着时间指数增加。达到它的平衡值所需的弛豫时间随表面吸引强度EPS的增加而减小,但平衡值随EPs增加,这表明强吸引时高分子吸附得更快,且更加扩展。高分子平行于表面的非球形因子在吸附过程中表现的行为与表观尺寸不同,对高分子链内部相互作用较敏感。在吸附过程中,表面接触链节数随着时间单调增加,但是高分子三维构象尺寸和形状非球形因子表现出新奇的行为。随着表面接触链节数的增加,它们先增加,然后减小,最后又增加。而二维构象尺寸和形状非球形因子随着表面接触链节数的增加先减小,然后增加。(2)吸附在均匀表面上的高分子的塌缩相变,研究了表面吸引强度EPS和链内吸引强度EPP对高分子相的影响。塌缩相变点和EPs有关,高分子构象和EPP、EPS有关。EPS小时,吸附链的构象是三维层状结构。EPs大时,EPP = 0的构象几乎是二维的,我们观察到二维塌缩相变和从二维构象到三维层结构的形成层相变,形成层相变点随着EPS的增加而增加。另外,我们发现吸附压制塌缩相变,也就是说,塌缩相变点随着EPS的增加而增加。(3)吸附在均匀吸引表面上的高分子链的动力学行为。平行于表面的平动扩散系数Dxy随着链内吸引强度EPP或表面吸引强度EPS的增加而减小。转动弛豫时间τR随着EPS的增加而增加,但是对EPP的依赖性和高分子的吸附状态有关。部分吸附链的转动弛豫时间随着EPP的增加而减小,但是完全吸附链的转动弛豫时间随着EPP的增加而增加。对于长链,标度关系Dxy～N-α和τR～N-β均成立。标度指数α和EPS无关,但随着EPP的增加而增加,EPP = 0时,α= 1.06。EPP = 0时,吸附链的β≈2.7,几乎和EPS无关。但EPP0时,β随着EPs的增加而增加。而且,我们发现β总是随着EPP的增加而减小。我们的结果揭示了吸引表面对吸附链的扩散和转动的不同影响。(4)随机吸引平面上高分子的吸附过程。临界吸附点分数随着表面吸引强度和链内吸引强度EPP的增加而减小。当表面吸引强度较大时,高分子平行于表面的表观尺寸的平衡值随着吸附点分数的增加先增加后减小。高分子的吸附时间随着表面吸引强度的增加而减小,但是随着EPP的增加而增加。另外,随机分布的吸附点使吸附链的平动扩散减慢。
[Abstract]:The adsorption of polymers on the surface is an important subject in the biological, physical and chemical fields. This is due to its universality and potential applications, such as polymer adhesives, colloid stabilization, polymer nanocomposites, coatings and lubrication. Isolation of DNA in bacteria, packaging of DNA in viruses and superhydrophobic / superhydrophilic materials. The adsorption, conformation and kinetic properties of polymers on attractive surfaces have been studied by Monte Carlo method. The main contents and results are as follows: 1) the adsorption process of the polymer on the homogeneous attractive surface. The apparent size of the polymer chain parallel to the surface increases with the time exponent during the adsorption process. The relaxation time required to reach its equilibrium value decreases with the increase of the surface attraction strength EPS, but the equilibrium value increases with the increase of the EPs value, which indicates that the polymer adsorbs more rapidly and expands with the strong attraction. The adsorption behavior of non-spherical factors parallel to the surface of polymers is different from that of the surface, and they are more sensitive to the internal interaction of polymer chains. In the process of adsorption, the number of surface contact chains increases monotonously with time, but the three-dimensional conformational size and shape non-spherical factors of polymer exhibit novel behavior. With the increase of the number of surface contact chains, they first increase, then decrease, and finally increase. However, with the increase of the number of contact chains on the surface, the two-dimensional conformational size and shape non-spherical factors decrease firstly, and then increase .t2) the collapse phase transition of the polymer adsorbed on the uniform surface. The effects of surface attraction strength (EPS) and intrachain attraction strength (EPP) on polymer phase were studied. The collapse phase transition point is related to EPs, and the conformation of macromolecule is related to EPPP-EPS. The conformation of adsorption chain is three-dimensional layer structure. EPS = 0 is almost two dimensional conformation. We observed the collapse phase transition in two dimensions and the cambium phase transition from two dimensional conformation to three dimensional layer structure. The phase transition point of cambium increases with the increase of EPS. In addition, we find that adsorption suppresses the collapse phase transition, that is, the kinetic behavior of the polymer chain adsorbed on the homogeneous attractive surface increases with the increase of EPS. The translational diffusion coefficient (Dxy), which is parallel to the surface, decreases with the increase of the intrachain attraction strength (EPP) or the surface attraction intensity (EPS). The rotational relaxation time 蟿 R increases with the increase of EPS, but the dependence on EPP is related to the adsorption state of polymer. The rotational relaxation time of partial adsorption chain decreases with the increase of EPP, but the rotational relaxation time of fully adsorbed chain increases with the increase of EPP. For long chains, the scale relationship Dxyn- 伪 and 蟿 RN- 尾 hold. The scale exponent 伪 is independent of EPS, but with the increase of EPP, the adsorption chain 尾 鈮，

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