Double gyroid surfaces

An increasing t is related to a monotonic increase/decrease in the volume of each of the two related networks and leads to an increase in the absolute mean curvature H, see Fig.2.2c. Correlated to the change in volume fraction is the growing offset of the surface from the t = 0 base surface. For t, the surface on one side of the minimal surface (t = 0) with a certain offset, while for —t the surface lies on the opposite side with the same offset. This behavior wiU become clearer when discussing the double-gyroid. 

Fig. 2.4 a Volume fraction of the double-gyroid network phase as function of the parameter t fitted with (/) = 101.5 — 68.1 -1. b Specific surface area to bulk volume ratio of the double-gyroid plotted versus the network phase volume fraction in units of the cubic unit cell dimension L... 

Fig. 4.1 Preparation of mesoporous thin film polymer templates on suitable substrates, a Substrate surface modification tailoring a neutral surface, b Copolymer film deposition and phase transition to the double-gyroid morphology during thermal annealing, c Selective degradation of PLA yields the mesoporous template...

The internal surface area of the double-gyroid structure formed by P(F)S49- -PLA192 was indirectly measured by hydrogen adsorption using cyclic voltammetry [44, 57, 58]. BET surface area measurements were not performed since larger quantities of the precious material would have been needed. For this purpose a platinum replica of the double-gyroid with a known deposition area (0.95 mm ) and thickness (1.15 p.m) was prepared by electroplating on a SU-8 patterned FTO substrate, see Fig. 4.21 [49]. The templated electrodeposition of platinum is discussed in detail in Chap. 6. 

Given that the density of electrodeposited nontemplated vanadia is 2.87 g cm , the average density of double-gyroid structured vanadia with a volume fraction of 37.9 % is1.09 g cm, illustrating the porous nature of the DG structure [16]. Thus, the specific surface area of DG-structured V2O5 is 1.48 m g . Furthermore, the mass m of vanadia electrodes was calculated using these densities, the electrode area and thickness. The V2O5 film thickness was determined by cross-sectional SEM or with a surface profilometer. 

Since TiCU merely reacts with hydroxyl groups, more reactive precursors such as TMA or DEZ are used for activation of other functional surface groups that do react with the latter in the optional Step 1. In the following, this ALD recipe for refilling the double-gyroid templates will be denoted as MetalOxide... 

For the refilling of the double-gyroid templates via electrochemical deposition a fully porous film/substrate interface was crucial while only a few pores at the free-surface are needed for electrolyte infiltration. Contrary, ALD requires a highly porous free-surface for efficient gas diffusion into the mesopores, while the porosity of the film/substrate interface is not relevant. Throughout this last part of the study, P(F)S49-174°C... 

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