Characterization by NMR measurements
1H- NMR was performed on a Bruker DRX-200 spectrometer from Bruker, Germany, equipped with a Diff30 probe, which provides z-gradients g up to about 12 T/m. A pulsed field gradient stimulated echo sequence (PFG-STE) sequence was applied [30]. Measurement parameters were similar to those in [31]. The gradient amplitude g was varied while keeping the diffusion time Δ fixed for discrete values of Δ between 60 and 360 ms, restricted by the longitudinal relaxation time of the oil T1oil = 350 ms. The spoiler gradient during longitudinal storage had an amplitude of 10–20% for a duration of 5 ms. The gradient duration δγ was 4 ms. The 90° pulse was adjusted to 10.8 μs at 0 dB (10 mm sample tubes). To avoid mechanical stress and possible structural changes of the double emulsions, glass tubes with an outer diameter of 10 mm were filled to a level of about 15 mm, corresponding to a total volume of about 0.75 cm3. For data processing, a self-written MATLAB® routine according to [22] was applied.