Interaction between a water-in-oil microemulsion and a linear-dendritic poly(propylene oxide)–polyglycerol block copolymer
Interaction between a water-in-oil microemulsion and a linear-dendritic poly(propylene oxide)–polyglycerol block copolymer
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油包水微乳液与线性树枝状聚环氧丙烷-聚甘油嵌段共聚物之间的相互作用
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发表时间：
2011
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通讯作者：
B. Stühn
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作者：
R. Wipf;M. Kraska;T. Spehr;Jörg Nieberle;H. Frey;B. Stühn
我们提出了小角散射和介电光谱的结果上的两亲性二嵌段共聚物的微乳液的结构和动力学的影响。我们使用基于阴离子表面活性剂AOT（双（2-乙基己基）磺基琥珀酸钠）的油包水（w/o）液滴微乳液，其形成由分散在连续油基质中的单层AOT包覆的球形水滴。所研究的聚合物由疏水性聚环氧丙烷（PPO）嵌段和亲水性超支化聚甘油与74甘油单元（NG 74）。结合小角中子散射（SANS）和小角X射线散射（SAXS），我们发现，液滴结构被保存后，添加PPO-NG 74，而液滴之间的相互作用距离随着聚合物含量的增加而增加。从SANS我们推断，NG 74块位于液滴内，而PPO延伸到油基质中。通过测量作为温度的函数的直流电导率，我们研究了微乳液的动态渗流。当液滴相的静态结构保持不变时，逾渗温度和相分离温度都随聚合物浓度的增加而线性增加。我们解释了这一发现由聚合物引起的AOT层的硬化。通过介电谱，我们观察到两个弛豫。较慢的一个可以与水核和AOT壳的界面处的极化（核弛豫）相关，而较快的一个是由于AOT壳中的离子（簇弛豫）。聚合物的加入被发现有一个显着的影响，只有对核心松弛。我们应用团簇弛豫模型来估计团簇尺寸随聚合物浓度的变化。
We present small angle scattering and dielectric spectroscopy results on the influence of an amphiphilic diblock copolymer on the structure and dynamics of a microemulsion. We use a water-in-oil (w/o) droplet microemulsion based on the anionic surfactant AOT (sodium bis(2-ethylhexyl) sulfosuccinate), that forms spherical water droplets coated by a monolayer of AOT dispersed in the continuous oil matrix. The studied polymer consists of a hydrophobic poly(propylene oxide) (PPO) block and a hydrophilic hyperbranched polyglycerol with 74 glycerol units (NG74). Combining small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) we find that the droplet structure is preserved upon addition of PPO-NG74 while the interaction distance between droplets increases with increasing polymer content. From SANS we deduce that the NG74 block is located inside the droplets while the PPO extends into the oil matrix. By measuring the dc-conductivity as a function of temperature we study the dynamic percolation of the microemulsion. While the static structure of the droplet phase remains unchanged, both percolation temperature and phase separation temperature increase linearly with increasing polymer concentration. We explain this finding by a stiffening of the AOT layer induced by the polymer. By means of dielectric spectroscopy we observe two relaxations. The slower one can be related to a polarization at the interface of the water core and the AOT shell (core relaxation) and the faster one is due to the ions in the AOT-shell (cluster relaxation). Polymer addition is found to have a significant influence only on the core relaxation. We apply the cluster relaxation model to estimate the cluster size evolution with increasing polymer concentration.