When Do Polyelectrolytes Entangle?
When Do Polyelectrolytes Entangle?
复制标题
DOI：
10.1021/acs.macromol.0c02450
复制
发表时间：
2021-02-01
期刊：
影响因子：
5.5
通讯作者：
Jacobs, Michael
中科院分区：
文献类型：
--
作者：
Dobrynin, Andrey, V;Jacobs, Michael
聚合物溶液中的纠缠态是高分子科学中一个有争议的问题。在过去的20年里，实验研究提出了怀疑的概念的适用性的纠缠开发的中性聚合物的聚电解质。为了解决这个问题，我们开发了一种方法的基础上的解决方案相关长度xi = lg（nu）/B和单体的数量之间的缩放关系的聚合物与单体投影长度l的每个相关滴g。数值系数B和指数nu由聚合物主链的溶剂质量、链Kuhn长度以及从溶液相关长度开始到静电和热滴长度尺度的不同长度尺度下的单体-单体相互作用的类型和强度确定。B参数的值由归一化比粘度η（sp）（c）（cl（3））（a）/N-w的平台获得，该平台是具有重均聚合度N-w的带电和中性聚合物的不同溶液状态中单体浓度c的函数。指数α = 1/（1 - 3 nu）描述了每个相关斑点的单体数量的浓度依赖性，g类似于c（α）。B参数的知识允许计算分别进入重叠的静电和热团块的溶液和浓缩的聚合物溶液的交叉浓度c（D）、c（th）和c**。它用于比粘度和弛豫时间数据的通用表示，单位为每条链的滴数N-w/g，可视为聚合物溶液中的有效链聚合度。通过将这种方法应用于缠结溶液体系中的粘度数据，我们获得了填充数（P）对波浪线（e）的依赖性和缠结之间的聚合度（N）对波浪线（e）的依赖性=（P）对波浪线（2）（e）g的依赖性，其中包括系统分散性信息。该分析表明，在聚合度高达10（4）的链的无盐溶液中，聚电解质仅在缠结浓度c（e）> c（D）且溶液性质类似于中性聚合物的溶液体系中缠结。从聚电解质在盐溶液中的粘度数据的分析得出类似的结论。因此，为了观察缠结的浓度范围内，它们的性质是由静电相互作用控制的溶液中，一个必须研究的聚合度的至少一个数量级以上的研究到目前为止的dielectric链。
Entanglements in polyelectrolyte solutions are a controversial issue in polymer science. Experimental studies during the last 20 years have raised doubts about the applicability of the concept of entanglements developed for neutral polymers to polyelectrolytes. To address this issue, we develop an approach based on the scaling relationship between the solution correlation length xi = lg(nu)/B and the number of monomers per correlation blob g for polymers with the monomer projection length l. The numerical coefficient B and exponent nu are determined by the solvent quality for the polymer backbone, chain Kuhn length, and type and strength of monomer-monomer interactions at different length scales starting from the solution correlation length down to electrostatic and thermal blob length scales. Values of the B parameters are obtained from plateaus of normalized specific viscosity eta(sp)(c)(cl(3))(a)/N-w as a function of the monomer concentration c in different solution regimes of charged and neutral polymers with the weight average degree of polymerization N-w. The exponent alpha = 1/(1 - 3 nu) describes the concentration dependence of the number of monomers per correlation blob, g similar to c(alpha). Knowledge of the B parameters allows calculations of crossover concentrations c(D), c(th), and c** into solutions of overlapping electrostatic and thermal blobs and concentrated polymer solutions, respectively. It is used for the universal representation of specific viscosity and relaxation time data in terms of the number of blobs per chain, N-w/g, which can be viewed as an effective chain degree of polymerization in polymer solutions. By applying this approach to viscosity data in the entangled solution regime, we obtain a packing number (P) over tilde (e) and a concentration dependence of the degree of polymerization between entanglements (N) over tilde (e) = (P) over tilde (2)(e)g, which include system dispersity information. This analysis shows that, in salt-free solutions of chains with degrees of polymerization of up to 10(4), polyelectrolytes only entangle in the solution regimes where the entanglement concentration c(e) > c(D) and solution properties are similar to those of neutral polymers. A similar conclusion is reached from analysis of viscosity data of polyelectrolytes in salt solutions. Therefore, in order to observe entanglements in polyelectrolyte solutions in a concentration range where their properties are controlled by electrostatic interactions, one has to study polyelectrolyte chains with degrees of polymerization of at least an order in magnitude longer than studied so far.