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首页> 外文期刊>Chemistry: A European journal >Cross-linking density and temperature effects on the self-assembly of SiO_2 - PNIPAAm core-shell particles at interfaces
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Cross-linking density and temperature effects on the self-assembly of SiO_2 - PNIPAAm core-shell particles at interfaces

机译：交联密度和温度对SiO_2-PNIPAAm核-壳颗粒界面自组装的影响

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摘要

SiO_2-PNIPAAm core-shell microgels (PNIPAAm=poly(N- isopropylacrylamide)) with various internal cross-linking densities and different degrees of polymerization were prepared in order to investigate the effects of stability, packing, and temperature responsiveness at polar-apolar interfaces. The effects were investigated using interfacial tensiometry, and the particles were visualized by cryo-scanning electron microscopy (SEM) and scanning force microscopy (SFM). The core-shell particles display different interfacial behaviors depending on the polymer shell thickness and degree of internal cross-linking. A thicker polymer shell and reduced internal cross-linking density are more favorable for the stabilization and packing of the particles at oil-water (o/w) interfaces. This was shown qualitatively by SFM of deposited, stabilized emulsion droplets and quantitatively by SFM of particles adsorbed onto a hydrophobic planar silicon dioxide surface, which acted as a model interface system. The temperature responsiveness, which also influences particle-interface interactions, was investigated by dynamic temperature protocols with varied heating rates. These measurements not only showed that the particles had an unusual but very regular and reversible interface stabilization behavior, but also made it possible to assess the nonlinear response of PNIPAAm microgels to external thermal stimuli. Softness matters: SiO_2-PNIPAAm core-shell microgels with various internal cross-linking densities and different degrees of polymerization were used to investigate the effects of stability, packing, and static/dynamic temperature responsiveness at polar-apolar interfaces (see figure). These particles displayed an unusual but very regular and reversible interface stabilization behavior and a nonlinear particle response to heat. PNIPAAm=poly(N- isopropylacrylamide)
机译：制备具有各种内部交联密度和不同聚合度的SiO_2-PNIPAAm核壳微凝胶（PNIPAAm =聚（N-异丙基丙烯酰胺）），以研究极性-非极性界面的稳定性，堆积和温度响应性的影响。使用界面张力法研究了效果，并且通过冷冻扫描电子显微镜（SEM）和扫描力显微镜（SFM）使颗粒可视化。核-壳颗粒根据聚合物壳的厚度和内部交联度表现出不同的界面行为。较厚的聚合物壳和降低的内部交联密度更有利于油-水（o / w）界面处颗粒的稳定和堆积。通过沉积的，稳定的乳液液滴的SFM定性显示了这一点，并通过吸附在疏水性平面二氧化硅表面（作为模型界面系统）上的颗粒的SFM定量地表明了这一点。通过改变加热速率的动态温度方案研究了温度响应性，该温度响应性也影响粒子-界面相互作用。这些测量不仅表明颗粒具有异常但非常规则且可逆的界面稳定行为，而且使评估PNIPAAm微凝胶对外部热刺激的非线性响应成为可能。柔软性很重要：使用具有各种内部交联密度和不同聚合度的SiO_2-PNIPAAm核壳微凝胶，研究了极性-非极性界面的稳定性，堆积和静态/动态温度响应性的影响（见图）。这些粒子显示出异常的但非常规则且可逆的界面稳定行为，以及粒子对热的非线性响应。 PNIPAAm =聚（N-异丙基丙烯酰胺）

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