Swollen micelles plus hydrophobically modified hydrosoluble polymers in aqueous solutions: Decoration versus bridging. A small angle neutron scattering study
Swollen micelles plus hydrophobically modified hydrosoluble polymers in aqueous solutions: Decoration versus bridging. A small angle neutron scattering study
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DOI：
10.1021/jp990980d
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发表时间：
1999-08-26
影响因子：
3.3
通讯作者：
Appell, J
中科院分区：
文献类型：
--
作者：
Filali, M;Aznar, R;Appell, J
在本文中，我们研究了水包油微乳液的液滴之间引入的有效相互作用后，逐步加入疏水改性的水溶性聚（环氧乙烷）（PEO），基本上使用小角中子散射。为了讨论装饰和桥接的液滴的相对重要性，我们比较了类似的样品与添加的PEO接枝在两端与疏水C12 H25链（PEO-2 m）或添加的PEO接枝在一端仅与C12 H25链（PEO-m）。PEO-m或PEO-2 m通过它们的疏水末端吸附到液滴上，并且发现在每个液滴添加多达40个疏水C12 H25链时，液滴保持它们的形式和尺寸。当液滴的体积分数小于约10%时，发现由PEO-m或PEO-2 m引入的有效相互作用非常不同：PEO-m引入排斥相互作用，而PEO-2 m引入有效吸引相互作用。当加入足够量的PEO-2 m时，这种有吸引力的相互作用导致在低体积分数范围内的缔合相分离。在较高的体积分数下，PEO-m或PEO-2 m对相互作用的贡献是很小的排斥贡献。我们定性地讨论了装饰或PEO聚合物链的液滴桥接的实验结果。
In this paper we examine the effective interactions introduced between the droplets of an oil in water microemulsion upon progressive addition of hydrophobically modified water soluble poly(ethylene oxide) (PEO) using essentially small angle neutron scattering. To discuss the relative importance of decoration and bridging of the droplets, we compare analogous samples with addition of a PEO grafted at both extremities with hydrophobic C12H25 chains (PEO-2m) or addition of a PEO grafted at one extremity only with a C12H25 chain (PEO-m). PEO-m or PEO-2m adsorb onto the droplets via their hydrophobic extremities, and the droplets are found to retain their form and size upon addition of up to 40 hydrophobic C12H25 chains per droplet. When the volume fraction of droplets is less than about 10%, the effective interactions introduced by PEO-m or PEO-2m are found to be very different: PEO-m introduces a repulsive interaction, while PEO-2m introduces an effective attractive interaction. This attractive interaction leads to an associative phase separation in the range of low volume fraction when a sufficient amount of PEO-2m is added. At higher volume fraction the contribution of PEO-m or PEO-2m to the interaction is a small repulsive contribution. We discuss qualitatively the experimental results in terms of decoration or bridging of the droplets by the PEO polymeric chains.