Menger sponge-like fractal body created by a novel template method

Abstract

We have established experimental strategies on how to create a Menger sponge-like fractal body and how to control its fractal dimension. The essence was to utilize alkylketene dimer (AKD), which spontaneously forms super-water-repellent fractal surface. We prepared "fractal AKD particles" with fractal surface structure as templates of pores in fractal body. The fractal body was synthesized by filling the remained space between the packed template particles with a tetramethyl orthosilicate solution, solidifying it by the sol-gel process, and removing the template by calcinations. We have succeeded in systematically creating fractal bodies of silica with different cross-sectional fractal dimensions D(cs)=1.87, 1.84, and 1.80 using "fractal template particles" compressed under the ratio=1.0, 2.0, and 3.0, respectively. We also discussed the possibilities of their fractal geometries in comparison with mathematical models. We concluded that the created fractal bodies were close to a Menger sponge and its modified one. Our experimental strategy allows us to design fractality of porous materials.

Characterization and structural investigation of fractal porous-silica over an extremely wide scale range of pore size

“…The principle is the melting temperature depression in small pores. The relation between melting depression T m and pore size r is [20] r H agreement with the findings in our previous work [17], but not dependent on T cal . We will discuss this point later from the viewpoint of the geometry of porous silica.…”

“…100 m [18]. The observed D values were close to those of Menger sponge-like structures at the range of 100 nm ~ 1 m as predicted in our previous work [17].…”

“…The fractal bodies were prepared as described elsewhere [17]. First, fractal particles were prepared by a spray technique using nitrogen gas (the gas flow rate is ~ 3 liter min-1) from a n-hexane (Wako) solution of alkylketene dimer (AKD, supplied by Arakawa Chemical Industries, Ltd.) at ca.…”

“…Very recently we have succeeded in creating "fractal body", porous-silica samples with Menger sponge-like fractal geometries, by a novel template method [17]. We utilized the template particles of AKD and a sol-gel synthesis of tetramethyl orthosilicate (TMOS), where AKD is a material of super water-repellent fractal surface and the template particles are corresponding to pores.…”

“…If one can estimate n, then the geometry can compare with the model. It can be obtained from the relation between the pore size reduction ratio and the cutoffs [17].…”