Leermakers Frans A M
Physical Chemistry and Soft Matter Wageningen University, Stippeneng 4, Wageningen, WE 6708, The Netherlands.
Macromolecules. 2020 May 26;53(10):3900-3906. doi: 10.1021/acs.macromol.0c00361. Epub 2020 May 13.
De Gennes predicted that homopolymer adsorption on a solid-liquid interface results in an adsorption profile with a proximal, a central, and a distal region, wherein, for a good solvent, the central region has a self-similar structure with a density profile that decays as a power law with a coefficient of -4/3. Recent numerical self-consistent field (SCF) predictions for the long-chain length () limit revealed a more complex central region with an inner part, where the loops dominate the layer, with a (mean-field) power-law coefficient of -2 and an outer part, where tails dominate, with a "de Gennes" scaling of -4/3. The tails with length < * contribute to the inner part of the central region, and these have similar conformations as the loops. The outer part is populated by tails with a length > *, and these behave differently. With the increasing length of the tails, there exists a weak escape transition at = ≈ /10. Long tails in the adsorption profile ( ≳ * ∝ ) show enhanced fluctuations due to this nearby escape transition, and this explains the excluded volume scaling for the outer part of the central region in SCF. With this interpretation, the -2 scaling found by SCF for the inner part should be classified as a mean-field result.
德热纳预测，均聚物在固液界面上的吸附会导致一种具有近端、中央和远端区域的吸附分布，其中，对于良溶剂，中央区域具有自相似结构，其密度分布以-4/3的系数按幂律衰减。最近针对长链长度（）极限的数值自洽场（SCF）预测揭示了一个更复杂的中央区域，其内部部分环主导吸附层，（平均场）幂律系数为-2，外部部分尾主导，具有-4/3的“德热纳”标度。长度<*的尾对中央区域的内部部分有贡献，并且它们的构象与环相似。外部部分由长度>的尾占据，并且它们的行为不同。随着尾长度的增加，在=≈/10处存在一个弱逃逸转变。吸附分布中的长尾（≳∝）由于这个附近的逃逸转变而表现出增强的涨落，这解释了SCF中中央区域外部部分的排除体积标度。基于这种解释，SCF在内部部分发现的-2标度应归类为平均场结果。
