Akinchina Anna, Shusharina Nadezhda P, Linse Per
Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
Langmuir. 2004 Nov 9;20(23):10351-60. doi: 10.1021/la0490386.
Spherical brushes composed of diblock polyampholytes (diblock copolymers with oppositely charged blocks) grafted onto solid spherical particles in aqueous solution are investigated by using the primitive model solved with Monte Carlo simulations and by lattice mean-field theory. Polyampholyte chains of two compositions are considered: a copolymer with a long and a short block, A100B10, and a copolymer with two blocks of equal length, A50B50. The B block is end-grafted onto the surface, and its charge is varied, whereas the charge of the A block is fixed. Single-chain properties, radial and lateral spatial distributions of different types, and structure factors are analyzed. The brush structure strongly depends on the charge of the B block. In the limit of an uncharged B block, the chains are stretched and form an extended polyelectrolyte brush. In the other limit with the charges of the blocks compensating each other, the chains are collapsed and form a polyelectrolyte complex surrounding the particles. At intermediate charge conditions, a polyelectrolyte brush and a polyelectrolyte complex coexist and constitute two substructures of the spherical brush. The differences of the brush structures formed by the A100B10 and A50B50 polyampholytes are also analyzed. Finally, a comparison of the predictions of the two theoretical approaches is made.
通过蒙特卡罗模拟求解的原始模型和晶格平均场理论，研究了由接枝到水溶液中固体球形颗粒上的双嵌段聚两性电解质（具有相反电荷嵌段的双嵌段共聚物）组成的球形刷。考虑了两种组成的聚两性电解质链：一种是具有长嵌段和短嵌段的共聚物A100B10，另一种是具有两个等长嵌段的共聚物A50B50。B嵌段末端接枝到表面，其电荷可变，而A嵌段的电荷固定。分析了单链性质、不同类型的径向和横向空间分布以及结构因子。刷状结构强烈依赖于B嵌段的电荷。在B嵌段不带电的极限情况下，链被拉伸并形成伸展的聚电解质刷。在嵌段电荷相互补偿的另一个极限情况下，链塌陷并形成围绕颗粒的聚电解质复合物。在中间电荷条件下，聚电解质刷和聚电解质复合物共存并构成球形刷的两个子结构。还分析了由A100B10和A50B50聚两性电解质形成的刷状结构的差异。最后，对两种理论方法的预测进行了比较。
