A scanning angle reflectometry investigation of block copolymer adsorption to insoluble lipid monolayers at the air-water interface
A scanning angle reflectometry investigation of block copolymer adsorption to insoluble lipid monolayers at the air-water interface
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DOI：
10.1021/jp9521619
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发表时间：
1996-02-22
影响因子：
--
通讯作者：
Tilton, RD
中科院分区：
文献类型：
--
作者：
Charron, JR;Tilton, RD
我们修改了扫描角反射法的技术，以测量表面过量浓度的水溶性聚苯乙烯-聚（环氧乙烷）（PS-PEO）二嵌段共聚物从溶液中吸附到二棕榈酰磷脂酰胆碱（DPPC）单分子膜蔓延在空气-水界面。聚合物通过渗透脂质单层而吸附。表面压力数据和荧光显微镜表明，PS-PEO吸附驱动的液体膨胀到液体的凝聚相转变的DPPC单层通过减少每个脂质的可用面积。因此，PS-PEO吸附在功能上等同于单层的机械压缩。因此，PS-PEO吸附的程度由DPPC单层容纳在不同制度的表面压力-面积等温线与渗透的单层的可压缩性。聚合物吸附到液体膨胀单分子膜增加界面的可压缩性，等于相变制度。在相变和液体膨胀状态下吸附到单层的聚合物链段迫使脂质从膨胀状态变为凝聚状态，从而为聚合物产生可接近的界面区域。在这些单层制度的聚合物表面浓度是无法区分的空气-水界面处获得的情况下，一个蔓延的单层。液体凝聚单层不能以这种方式容纳聚合物链段，因此，聚合物吸附的程度降低。
We modified the technique of scanning angle reflectometry to measure the surface excess concentration as water-soluble polystyrene-poly(ethylene oxide) (PS-PEO) diblock copolymers adsorb from solution to dipalmitoylphosphatidylcholine (DPPC) monolayers spread at the air-water interface. Polymers adsorb by penetrating the lipid monolayer. Surface pressure data and fluorescence microscopy indicate that PS-PEO adsorption drives the liquid expanded-to-liquid condensed phase transition in the DPPC monolayer by decreasing the available area per lipid. PS-PEO adsorption is therefore functionally equivalent to mechanical compression of the monolayer. Accordingly, the extent of PS-PEO adsorption accommodated by DPPC monolayers in different regimes of the surface pressure-area isotherm correlates with the compressibility of the penetrated monolayers. Polymer adsorption to Liquid expanded monolayers increases the interface compressibility to equal that of the phase transition regime. Polymer segments that adsorb to monolayers in the phase transition and the liquid expanded regimes force lipids from the expanded to the condensed state, thereby creating accessible interfacial area for the polymer. Polymer surface concentrations in those monolayer regimes are indistinguishable from those attained at the air-water interface in the absence of a spread monolayer. Liquid condensed monolayers cannot accommodate polymer segments in this way, and as a result, the extent of polymer adsorption is diminished.