EPR Spectroscopy as an Efficient Tool for Investigations of Polyelectrolyte Multilayer Growth and Local Chain Dynamics.
EPR Spectroscopy as an Efficient Tool for Investigations of Polyelectrolyte Multilayer Growth and Local Chain Dynamics.
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DOI：
10.1021/acs.jpcb.1c02692
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发表时间：
2021-05
期刊：
影响因子：
--
通讯作者：
Carolin Naas;U. Scheler;U. Lappan
中科院分区：
文献类型：
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作者：
Carolin Naas;U. Scheler;U. Lappan
采用强聚阳离子型聚二烯丙基二甲基氯化铵（PDADMAC）和弱聚阴离子型聚（乙烯-alt-马来酸）（P（E-alt-MA））制备了最多达31层的多层膜。一个自旋标记（SL）共价连接到聚阴离子的研究使用连续波（CW）电子顺磁共振（EPR）光谱的聚电解质的溶胀状态下的聚酸骨架的旋转动力学。在第一步中，自旋标记的聚（乙烯-alt-马来酸）（SL-P（E-alt-MA））被用于每个聚阴离子层，通过分析光谱的积分强度来监测PEM的生长。发现积聚是pH依赖性的，导致PEM具有不同的厚度。在第二步中，SL-P（E-alt-MA）被选择性地放置在一个单一的聚阴离子层中，以研究多酸骨架的旋转动力学。的旋转扩散系数的多酸骨架RS和内部旋转扩散系数的SL连接到聚合物骨架RI被发现是在pH 5比在pH 4，这是有关增强的流动性。
The strong polycation poly(diallyldimethylammonium chloride) (PDADMAC) and the weak polyanion poly(ethylene-alt-maleic acid) (P(E-alt-MA)) were used to build polyelectrolyte multilayers (PEMs) up to 31 layers. A spin-label (SL) was covalently attached to the polyanion for studying the rotational dynamics of the polyacid backbone in a swollen state of the PEMs using continuous-wave (CW) electron paramagnetic resonance (EPR) spectroscopy. In the first step, the spin-labeled poly(ethylene-alt-maleic acid) (SL-P(E-alt-MA)) was used in every polyanion layer to monitor the PEMs growth by analyzing the integrated intensity of the spectra. The buildup was found to be pH-dependent resulting in PEM with different thicknesses. In the second step, SL-P(E-alt-MA) was selectively placed in a single polyanion layer to study the rotational dynamics of the polyacid backbone. The rotational diffusion coefficient of the polyacid backbone RS and the internal rotational diffusion coefficient of the SL attached to the polymer backbone RI were found to be higher at pH 5 than at pH 4, which is related to enhanced mobility.