Two-dimensional lamellar phase of poly(styrene sulfonate) adsorbed onto an oppositely charged lipid monolayer.
Two-dimensional lamellar phase of poly(styrene sulfonate) adsorbed onto an oppositely charged lipid monolayer.
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聚（苯乙烯磺酸盐）的二维层状相吸附在带相反电荷的脂质单层上。
DOI：
10.1021/la802987k
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
C. Helm
中科院分区：
文献类型：
--
作者：
J. Günther;H. Ahrens;C. Helm
通过 X 射线反射率和掠入射衍射研究了空气/水界面上吸附在带相反电荷的双十八烷基二甲基溴化铵 (DODA) 单层上的聚苯乙烯磺酸盐 (PSS 77 kDa)。 DODA在凝聚相中的烷基尾部形成具有大倾角和中间方位角的斜晶格。 PSS吸附时，烷基尾部结构得以保持；仅倾斜角度发生变化。当 DODA 处于流体中以及处于凝聚相时，可以观察到由平坦吸附、对齐的 PSS 链引起的布拉格峰。二维层状相仅在中等 PSS 体积浓度 (0.001-1 mmol/L) 下发现。在此阶段，PSS 覆盖范围可以变化 3 倍，具体取决于 DODA 分子面积和聚合物本体浓度。层状相的电荷补偿几乎在 1 mmol/L 时实现。在较大的体积浓度下，PSS 吸附平坦，但没有链排列。据推测，二维层状相的必要条件是明显的静电力，它会导致大的持久长度以及排列链之间的排斥力。
Polystyrene sulfonate (PSS 77 kDa) adsorbed onto oppositely charged dioctadecyldimethylammonium bromide (DODA) monolayers at the air/water interface is investigated with X-ray reflectivity and grazing incidence diffraction. The alkyl tails of DODA in the condensed phase form an oblique lattice with large tilts and intermediate azimuth angle. On PSS adsorption, the alkyl tail structure is maintained; only the tilt angle changes. Bragg peaks caused by flatly adsorbed, aligned PSS chains are observed, when DODA is in the fluid and also when it is in the condensed phase. The two-dimensional lamellar phase is only found at intermediate PSS bulk concentrations (0.001-1 mmol/L). In this phase, the PSS coverage can be varied by a factor of 3, depending on DODA molecular area and polymer bulk concentration. Charge compensation in the lamellar phase is almost achieved at 1 mmol/L. At larger bulk concentrations, PSS adsorbs flatly yet without chain alignment. Presumably, a necessary condition for a two-dimensional lamellar phase is a pronounced electrostatic force which causes a large persistence length as well as repulsion between the aligned chains.