Polyelectrolyte multilayers under compression: concurrent osmotic stress and colloidal probe atomic force microscopy†,Soft Matter

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Polyelectrolyte multilayers under compression: concurrent osmotic stress and colloidal probe atomic force microscopy†
Soft Matter ( IF 2.9 ) Pub Date : 2018-01-02 00:00:00 , DOI: 10.1039/c7sm02177a
Bo Wu _{1,

2,

3,

4,

5} , Guangming Liu _{1,

2,

3,

4,

5} , Guangzhao Zhang _{5,

6,

7,

8} , Vincent S. J. Craig _{9,

10,

11,

12,

13}

Affiliation

Colloidal interactions have been characterised using both osmotic stress and surface forces. Here these methods are employed concurrently to measure the interaction forces of polyelectrolyte multilayers that when cross-linked form a dextran impermeable membrane. The force data, corrected for the thickness of the polyelectrolyte multilayer film, has been expressed as pressure versus separation enabling the interaction from osmotic stress measurements to be compared to the measured interaction from the colloid probe technique. The combined technique is valuable in evaluating the interaction forces associated with compression of polymer films at different rates and over a wide range of pressure and demonstrates features that are not revealed when just one technique is employed. The combination of the techniques allows both attractive forces and strongly repulsive forces to be measured and shows that the measured repulsion is greater in the force data than in the osmotic data. This is due to insufficient equilibration time in the AFM measurements, even at the slowest approach rates available, indicating that AFM force measurements between polyelectrolytes will always contain a dynamic component. That is we demonstrate that colloid probe measurements between polymer surfaces overestimate the equilibrium repulsive interaction due to the rate at which the measurement is performed.

中文翻译：

压缩条件下的聚电解质多层膜：同时存在的渗透压和胶体探针原子力显微镜†

胶体相互作用已使用渗透压力和表面力进行了表征。在此，同时使用这些方法来测量聚电解质多层的相互作用力，该多层电解质在交联时形成葡聚糖不可渗透的膜。校正了聚电解质多层膜厚度的力数据已表示为压力与分离可以将渗透压测量的相互作用与胶体探针技术测量的相互作用进行比较。组合技术对于评估与聚合物膜在不同速率和大范围压力下的压缩相关的相互作用力非常有价值，并且证明了仅采用一种技术时并未揭示的特征。这些技术的组合允许同时测量吸引力和强烈排斥力，并显示在力数据中所测得的排斥力比在渗透数据中所测得的排斥力更大。这是由于即使在最慢的接近速率下，AFM测量中的平衡时间不足，也表明聚电解质之间的AFM力测量将始终包含动态分量。

更新日期：2018-01-02

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