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首页> 外文期刊>Macromolecules >Standard Definitions of Persistence Length Do Not Describe the Local 'Intrinsic' Stiffness of Real Polymer Chains
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Standard Definitions of Persistence Length Do Not Describe the Local 'Intrinsic' Stiffness of Real Polymer Chains

机译：持久长度的标准定义没有描述实际聚合物链的局部“固有”刚度

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摘要

On the basis of extensive Monte Carlo simulations of lattice models for linear chains under good and Theta solvents conditions, and for bottle-brush polymers under good solvent conditions, different methods to estimate the persistence lengths of these polymers are applied and compared to each other. While for chain molecules at the Theta point standard textbook definitions of the persistence length yield consistent results, under good solvent conditions the persistence length (according to its standard definitions) diverges when the chain length of the macromolecules tends to infinity. Accurate simulation results for chain lengths up to N-b = 6400 allow us to verify the theoretically predicted power laws for the decay of the bond orientational correlation function. For the case of bottle-brush polymers, this dependence of "the" persistence length on the backbone chain length obscures the dependence on the side chain length, that is controversially discussed in the literature. Alternative definitions Or a persistence length that do not suffer from this problem, based on the total linear dimension of the chain or on the scattering function via the so-called "Holtzer plateau" are studied as well. We show that the backbone contour length of the bottle-brush needs to be very large (about 100 persistence lengths in typical cases) to reach the asymptotic limit where the bottle-brush satisfies the self-avoiding walk statistics, and where a well-defined persistence length can be extracted. An outlook to pertinent experimental work is given.
机译：基于在良好和Theta溶剂条件下线性链和在良好溶剂条件下瓶刷聚合物的晶格模型的广泛Monte Carlo模拟，应用了估算这些聚合物持久性长度的不同方法，并将其相互比较。尽管对于Theta点上的链分子，持久性长度的标准教科书定义产生了一致的结果，但是在良好的溶剂条件下，当大分子的链长趋于无穷大时，持久性长度（根据其标准定义）会发生变化。精确的链长高达N-b = 6400的模拟结果使我们能够验证理论上预测的键取向相关函数衰减的幂律。对于瓶刷聚合物，持久性长度对主链长度的这种依赖性掩盖了对侧链长度的依赖性，这在文献中有争议。还基于链的总线性尺寸或基于经由所谓的“霍尔兹高原”的散射函数，研究了替代定义或不受该问题困扰的持久长度。我们表明，奶瓶的骨架轮廓长度必须非常大（在典型情况下约为100个持久性长度），才能达到渐近极限，在该极限处，奶瓶满足自动避开行走统计的要求，并且其中定义明确持久性长度可以提取。展望了相关实验工作。

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