Evolution of Single Chain Conformation for Model Comb-Like Chains with Grafting Density Ranging from 0 to ∼100% in Dilute Solution,ACS Macro Letters

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Evolution of Single Chain Conformation for Model Comb-Like Chains with Grafting Density Ranging from 0 to ∼100% in Dilute Solution
ACS Macro Letters ( IF 5.1 ) Pub Date : 2019-11-11 , DOI: 10.1021/acsmacrolett.9b00711
Xuejun Pan ₁ , Muhammad Waqas Ishaq ₁ , Ahmad Umair ₁ , Muhammad Waqas Ali ₂ , Lianwei Li _{1,

3}

Affiliation

This work aims to experimentally clarify how the single chain conformation evolves as a function of grafting density for model comb-like chains in dilute solution in the whole density regime. Via a combination of rational design, precise synthesis and accurate characterization, we obtained four sets of PPA_Nb-g-PS₃₀-σ comb-like samples with well-defined architectures and accurately extracted their molecular parameters by triple detection size exclusion chromatography (TD-SEC). With these samples in hand, we quantified how the excluded volume interaction and chain conformation evolve with the grafting density (σ) in the whole density regime. Three main findings are reported: (i) the graft–graft excluded volume interaction is not ignorable even in the low σ-regime; (ii) contrary to theoretical predictions, both the excluded volume interaction and the chain conformation are found to be N_b-dependent; (iii) both R_g ∼ σ^1/3 and [η] ∼ σ⁰ are experimentally confirmed for comb-like chains from different σ and N_b, signifying a unique 3D mass-size growth pattern and a quasi-3D fractal feature. The obtained results help clarify some long-existed controversial issues in the field.

中文翻译：

稀溶液中接枝密度从0到~100%的模型梳状链的单链构象演变

这项工作旨在通过实验阐明单链构象如何随着整个密度范围内的稀溶液中的模型梳状链的接枝密度而演变。通过合理设计、精密合成和准确表征相结合，我们得到了四组PPA _{N b} - g -PS ₃₀-σ 梳状样品具有明确的结构，并通过三重检测尺寸排阻色谱 (TD-SEC) 准确提取其分子参数。有了这些样品，我们量化了排除的体积相互作用和链构象如何随着整个密度范围内的接枝密度 (σ) 演变。报告了三个主要发现：（i）即使在低 σ 状态下，移植物 - 移植物排除体积相互作用也不容忽视；(ii) 与理论预测相反，发现排除的体积相互作用和链构象都依赖于N _{b ；}(iii)对于来自不同 σ 和N的梳状链，R _g ∼ σ ^1/3和 [η] ∼ σ ^{0均通过实验证实}_b，表示独特的 3D 质量大小增长模式和准 3D 分形特征。所得结果有助于澄清该领域一些长期存在的争议问题。

更新日期：2019-11-13

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