Size and pH effect on electrical and conformational behavior of poly(acrylic acid): Simulation and experiment
Size and pH effect on electrical and conformational behavior of poly(acrylic acid): Simulation and experiment
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DOI：
10.1016/j.eurpolymj.2005.11.023
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发表时间：
2006-05-01
影响因子：
6
通讯作者：
Buffle, Jacques
中科院分区：
文献类型：
--
作者：
Laguecir, Abohachem;Ulrich, Serge;Buffle, Jacques
采用蒙特卡罗模拟、实验滴定和荧光相关光谱实验研究聚丙烯酸（PAA）的构象和电学性质。一方面，计算滴定曲线以深入了解 pH 对 PAA 链电离度和构象的作用。另一方面，对于不同的 PAA 分子量，也实现了 PAA 的实验电位滴定，并与通过蒙特卡罗粗粒度模拟获得的计算滴定曲线进行了比较。研究发现，对于大范围的中间 PAA 电离，由于该域中静电相互作用的突出，实验数据和模拟数据之间获得了良好的相关性。还研究了离子浓度和 PAA 分子量对滴定曲线的影响。为了更好地了解 PAA 构象行为，我们还通过荧光相关光谱 (FCS) 研究了 PAA 在水溶液中的扩散特性作为 pH 和离子强度的函数，这得益于其测量示踪溶质扩散系数的高灵敏度。在实验扩散率和通过 MC 模拟计算出的聚合物性能之间观察到良好的定性一致性。结果表明，高分子量 PAA 链在扩散率方面表现出更显着的变化，与模拟中观察到的电离度和构象变化一致。 (C) 2005 Elsevier Ltd. 保留所有权利。
Monte Carlo simulations, experimental titrations and fluorescence correlation spectroscopy experiments were used to investigate the conformational and electrical properties of polyacrylic acids (PAA). On the one hand.. titration curves were calculated to get an insight into the role of pH on the degree of ionization and conformation of PAA chains. Oil the other hand, experimental potentiometric titrations of PAA were also achieved for different PAA molecular weights and compared to the calculated titration curves obtained by Monte Carlo coarse grained simulations. It was found that for a large range at intermediate PAA ionizations, a good correlation is obtained between experimental and simulations data thanks to the prominence of electrostatic interactions in this domain. The effect of ionic concentration and PAA molecular weight on the titration curves was also investigated. In order to get a better understanding of PAA conformational behavior, we also investigated PAA diffusion properties in aqueous solutions as a function of pH and ionic strength by fluorescence correlation spectroscopy (FCS), thanks to its high sensitivity to measure diffusion coefficients of tracer solutes. Good qualitative agreements were observed between experimental diffusivities and polymer properties calculated from MC simulations. It was shown that the high molecular weight PAA chains display more significant changes in diffusivity in agreement with the ionization degrees and conformational changes observed ill the simulations. (C) 2005 Elsevier Ltd. All rights reserved.