Adsorption/Depletion Transition of Polymer Chains on the Inner Surface of a Spherical Shell

作者：Lu, Yang; Qu, Li-jian^*

来源：Acta Polymerica Sinica, 2017, (3): 549-555.

DOI：10.11777/j.issn1000-3304.2017.16125

• Self-consistent field theory
• Adsorption
• Depletion
• Confinement

The present study applies the numerical self-consistent field theory (SCFT) to the polymer solution confined in a sphere, which is relevant for many technological and biological applications. This paper focuses on the adsorption/depletion transition of the polymer chains near the inner surface of the confining spherical shell. Dependence of the density profiles of the confined polymers on the radius of the confining wall, the polymer-wall interaction, and the mean polymer concentration are analysed from the numerical results of SCFT. It is found that the polymer segments distribute uniformly near the centre of the confining sphere and inhomogeneously near the confining shell. When the radius of the confining sphere is large enough, the confined polymers behave similarly to those near a flat plane. The lower the mean concentration of the confined polymer segments is, the more sensitive the thickness of the adsorption or depletion layer is to the sphere radius. The density profiles of the polymers and the thickness of the adsorption or depletion layer indicate that the adsorption/depletion transition can take place under specified conditions. The transition depends on the dimension of the confining sphere, the polymer chain length, the mean concentration, as well as the polymer-wall interaction. A linear relationship between the critical polymer-wall interaction parameter at the transition point and the reciprocal value of the chain length is observed from the numerical results of SCFT. Similar behaviour has also been found in the polymer chains near a flat plane. However, the slope and the intercept of the linear relationship here are functions of the radius of the sphere when the confining effect comes into play. It is found that higher critical attraction energy between the polymers and the wall is needed for adsorption/depletion transition to occur for smaller confining sphere. In other words, it is more difficult for the adsorption/depletion transition to occur.

• 出版日期2017-3-20
• 单位防灾科技学院