pH-Dependent complexation and polyelectrolyte chain conformation of polyzwitterion–polycation coacervates in salted water,Soft Matter

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pH-Dependent complexation and polyelectrolyte chain conformation of polyzwitterion–polycation coacervates in salted water
Soft Matter ( IF 2.9 ) Pub Date : 2021-09-13 , DOI: 10.1039/d1sm00880c
Kehua Lin ₁ , Benxin Jing ₁ , Yingxi Zhu ₁

Affiliation

The phase behavior and chain conformational structure of biphasic polyzwitterion–polyelectrolyte coacervates in salted aqueous solution are investigated with a model weak cationic polyelectrolyte, poly(2-vinylpyridine) (P2VP), whose charge fraction can be effectively tuned by pH. It is observed that increasing the pH leads to the increase of the yielding volume fraction and the water content of dense coacervates formed between net neutral polybetaine and cationic P2VP in contrast to the decrease of critical salt concentration for the onset of coacervation, where the P2VP charge fraction is reduced correspondingly. Surprisingly, a single-molecule fluorescence spectroscopic study suggests that P2VP chains upon coacervation seem to adopt a swollen or an even more expanded conformational structure at higher pH. As the hydrophobicity of P2VP chains is accompanied by a reduced charge fraction by increasing the pH, a strong pH-dependent phase and conformational behaviors suggest the shift of entropic and enthalpic contribution to the underlying thermodynamic energy landscape and chain structural dynamics of polyelectrolyte coacervation involving weak polyelectrolytes in aqueous solution.

中文翻译：

盐水中聚两性离子-聚阳离子凝聚层的pH依赖性络合和聚电解质链构象

用模型弱阳离子聚电解质聚（2-乙烯基吡啶）（P2VP）研究盐水溶液中双相聚两性离子-聚电解质凝聚层的相行为和链构象结构，其电荷分数可以通过pH值有效调节。据观察，增加 pH 会导致净中性聚甜菜碱和阳离子 P2VP 之间形成的致密凝聚层的产量体积分数和含水量增加，而凝聚开始时临界盐浓度降低，其中 P2VP 电荷分数相应减少。令人惊讶的是，单分子荧光光谱研究表明，凝聚后的 P2VP 链似乎在更高的 pH 值下采用膨胀或什至更大的构象结构。

更新日期：2021-09-22

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