| Abstract
| - Sol−gel nanocasting is used to imprint the soft-matter structures of lyotropic phases of nonionic n-alkyl−poly(ethylene oxide) amphiphiles (“CxEy”) into solid porous silica. Small angle X-ray scattering (SAXS),nitrogen sorption, and transmission electron microscopy (TEM) are used to investigate the dependence of theporosity on the block lengths or the block volumes, respectively. It is found that the size of the mesoporesis a function of the lengths/volumes of both the alkyl chain (NA) and the PEO block (NB). Moreover, thematerials contain a substantial degree of additional microporosity. A quantitative model is developed thatrelates the amphiphile organization during the nanocasting to the size of the mesopores and the microporosity.In particular, it turns out that depending on the number of EO units a fraction of the PEO chains contributesto the mesoporosity, while a significant portion leads to additional micropores. This model provides aquantitative description of the distribution of the hydrophobic and hydrophilic blocks within the lyotropicphase itself. Our findings indicate that the interface areas b2 of single surfactant chains are a function of theblock lengths, which can be described by a scaling law b2 ∝ NA0.16NB0.4. Mixtures of chemically equivalentamphiphiles with different block ratios are studied in further detail. It is seen that every pore size between thesize originating from the “parent” templates can be adjusted simply by mixing various amounts of twosurfactants, proving that true mixed phases act as a template for the silica pores.
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