Study of the surfactant role in latex–aerogel systems by scanning transmission electron microscopy on aqueous suspensions

Abstract

SummaryFor insulation applications, boards thinner than 2 cm are under design with specific thermal conductivities lower than 15 mW m −1 K −1 . This requires binding slightly hydrophobic aerogels which are highly nanoporous granular materials. To reach this step and ensure insulation board durability at the building scale, it is compulsory to design, characterise and analyse the microstructure at the nanoscale. It is indeed necessary to understand how the solid material is formed from a liquid suspension. This issue is addressed in this paper through wet-STEM experiments carried out in an Environmental Scanning Electron Microscope (ESEM). Latex-surfactant binary blends and latex-surfactant-aerogel ternary systems are studied, with two different surfactants of very different chemical structures. Image analysis is used to distinguish the different components and get quantitative morphological parameters which describe the sample architecture. The evolution of such morphological parameters during water evaporation permits a good understanding of the role of the surfactant.

Electron tomography on latex particles suspended in water using environmental scanning electron microscopy

“…images (Perret et al, 2018). However, a second mode around 110 nm is present on the diameter distribution.…”

“…In order to investigate more deeply the resolution which can be obtained on aqueous suspensions of latex particles, a surfactant is added to the suspension. The sizes of the surfactant shell and the latex core have been quantitatively measured in liquid and in the dry state (Perret et al, 2018). Figure 6a and Figure 6b display the STEM image acquired at 0° extracted from a tilted image series, and orthogonal cross sections extracted from the reconstructed volume, respectively.…”

X-ray Tomography Coupled with Finite Elements, A Fast Method to Design Aerogel Composites and Prove Their Superinsulation Experimentally

“…In particular, two kinds of this material are analyzed: a granular aerogel pile-up and a granular aerogel composite (aerogel + binder system). The organic composite has the following composition in dry weight fraction: organic binder (0.11), large granules(0.53), and small granules(0.35), (please refer to [ 12 ] for additional information on the binder). The characteristics of the samples studied are summarized in Table 1 in growing order of complexity, (first the aerogel pile-up only, then the composite ones).…”

“…Formulation trends to optimize these SIMs available in the literature comprise: (i) adding reinforcing fibers within aerogel slurry [ 11 ]; (ii) adding translucent polymer sheets on each side of the SIM; (iii) adding a binder [ 12 ]; (iv) and adding an opacifier [ 13 , 14 ]. Since the best additive materials have conductivities 10 (organic) to 40 times (mineral) higher than aerogel, they should be used in very low volume fraction, otherwise conductivity is impaired.…”

Characterization of Complex Micellar Systems by Scattering Techniques (Saxs and Sans) and Wet-Scanning Transmission Electron Microscopy (Wet-Stem)

“…This technique allows observing directly nanometer scale solids dispersed in solutions as well as their dynamics [32]. Wet-STEM has also been used to characterize biological materials [33,34], latex-aerogel systems [35], colloidal suspensions, mini-emulsions [30] and soft matter such as micelles [31] and vesicles [36]. The resolution of this technique is in the order of few nanometers [31,33].…”