Size and Diffusivity of Polymer Rings in Linear Polymer Matrices: The Key Role of Threading Events
Size and Diffusivity of Polymer Rings in Linear Polymer Matrices: The Key Role of Threading Events
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线性聚合物基体中聚合物环的尺寸和扩散率：螺纹事件的关键作用
DOI：
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
V. Mavrantzas
中科院分区：
文献类型：
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作者：
D. Tsalikis;V. Mavrantzas
对环状聚氧乙烯(PEO)分子在线性聚氧乙烯(PEO)链基质中的稀溶液进行了长分子动力学模拟，系统地改变了环和主链的分子长度。我们的重点是线性链大小对客环分子微观结构、构象和动力学的影响，以及这些性质如何与纯环熔体中相应的性质变化。在所有模拟的环线状共混物中，都发现环状分子显著膨胀。由于过量的链端自由体积效应，环膨胀在非常短的线性链(分子量小于约1.5公斤/摩尔)的基质中更为明显。在这些非常短的线性宿主中，所有模拟的PEO环(分子量在2到10公斤/摩尔之间)在它们自己的熔体中扩散得更快。然而，当主体线链的尺寸超过缠结分子质量时，环的扩散性显著降低。有趣的是，对于模拟的较短的PEO环(分子量等于2公斤/摩尔)，长的缠绕矩阵中的扩散系数接近一个与基质分子量无关的恒定值，而较长的环(分子量分别等于5K和10k g/摩尔)的扩散系数不断减小(至少对于这里所考察的线性矩阵分子量是这样)。我们对PEO环在线性PEO矩阵中扩散系数的模拟预测与Kruteva等人最近的脉冲场梯度核磁共振测量结果非常好地吻合。[大分子2017，50,9482-9493]。详细的拓扑分析表明，长环分子被主体线型链严重缠绕。因此，它们的节段性和扩散性受到线条的创建和释放速度的控制。在我们的分析中详细量化的线条也被认为会导致主体线性链的瞬时构象的强烈波动，从而影响它们的平均尺寸。我们的工作提供了强有力的证据，证明环线螺线是控制环线聚合物共混物的尺寸、构象和动态行为的关键机制。
Long molecular dynamics simulations are performed for dilute solutions of ring poly(ethylene oxide) (PEO) molecules in matrices of linear PEO chains where we systematically vary the molecular length of the ring and host chains. Our focus is on the effect of linear chain size on microscopic structure, conformation, and dynamics of the guest ring molecules, and how these properties vary with the corresponding ones in the pure ring melts. Ring molecules are found to be significantly swollen in all ring–linear blends simulated. Ring swelling is more pronounced in matrices of very short linear chains (molecular weights less than about 1.5 kg/mol) due to excess, chain-end free-volume effects. In these very short linear hosts, all PEO rings simulated (molecular weights between 2 and 10 kg/mol) diffuse faster than in their own melts. However, as the size of the host linear chains increases above the entanglement molecular weight, the diffusivity of rings decreases considerably. Interestingly enough, for the shorter PEO rings simulated (molecular weight equal to 2 kg/mol), the diffusion coefficient in long, entangled matrices approaches a constant value independent of the molecular weight of the matrix, whereas that of longer rings (molecular weight equal to 5k and 10k g/mol) decreases continuously (at least for the linear matrix molecular weights examined here). Our simulation predictions for the diffusion coefficient of PEO rings in the linear PEO matrices compare remarkably well with the recent pulse-field gradient NMR measurements of Kruteva et al. [Macromolecules 2017, 50, 9482–9493]. A detailed topological analysis reveals that long ring molecules are heavily threaded by the host linear chains. Their segmental and diffusive dynamics is therefore governed by the rate with which threadings are created and released. Threadings, which are quantified in detail in our analysis, are also seen to cause strong fluctuations in the instantaneous conformation of the host linear chains, thus influencing their average dimensions. Our work provides strong evidence that ring–linear threadings is the key mechanism governing the size, the conformation, and the dynamic behavior of ring–linear polymer blends.
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影响因子：
7.015
作者：
Michieletto, Davide;Marenduzzo, Davide;Turner, Matthew S.
通讯作者：
Turner, Matthew S.
影响因子：
41.2
作者：
Kapnistos M;Lang M;Vlassopoulos D;Pyckhout-Hintzen W;Richter D;Cho D;Chang T;Rubinstein M
通讯作者：
Rubinstein M
影响因子：
4.6
作者：
Lee, Eunsang;Kim, Soree;Jung, YounJoon
通讯作者：
Jung, YounJoon
影响因子：
5.5
作者：
Ge T;Panyukov S;Rubinstein M
通讯作者：
Rubinstein M
DOI：
10.1016/j.tig.2017.12.010
发表时间：
2018-04
期刊：
Trends in genetics : TIG
影响因子：
--
作者：
Paulsen T;Kumar P;Koseoglu MM;Dutta A
通讯作者：
Dutta A