Laponite and hybrid surfactant/laponite particles processed as spheres by spray-drying

Abstract

Laponite elementary disc crystals dispersed in water in the presence or absence of non-ionic Brij58 surfactant have been used as nanobuilding blocks to form laponite and laponite/surfactant spherical particles by spray-drying. The size distribution of the spherical spray-dried particles ranges from 70 to 1000 nm (average size about 220 nm). Although raw laponite (RL) was almost totally exfoliated in water, the spray-dried spherical particles were found partially delaminated and stable when spread into water. Based on a full characterization by several techniques such as dynamic light scattering, scanning and transmission electron microscopies, X-ray diffraction, thermal analyses, nitrogen volumetric sorption and solid-state multi-nuclear NMR studies, a mechanism has been proposed to explain the formation of the spherical micron size particles: a face-to-face and edge-to-edge stacking of the elementary disc crystals leads to the formation of few-layer laponite platelets that aggregate within the restricted volume of water droplets during the drying stage. In the presence of Brij58, elementary disc crystals are covered by surfactant molecules adsorbed on their surface. As a consequence, surfactant molecules fill the interlayer space to form spherical Brij58/laponite nanocomposite particles. These spray-dried laponite and Brij58/laponite spherical particles present a high potential for sorption applications. IntroductionDuring recent decades the interest towards nanoparticles has mainly increased because of their properties such as surface reactivity that are different from those of the bulk material. However, decreasing the size brings disadvantages such as toxicity 1 and/or manipulation difficulties. 2 Nanoparticles are interesting, not only for their unique properties, but also for their potential to be used as nanobuilding blocks. Interest in nanobuilding blocks is growing as they have been recognized to be basic units for the elaboration of hierarchically-organized materials by self-assembling processes. 3,4 As there are various types of inorganic nanobuilding blocks and several ways to link them together, the resulting materials are numerous. 5 Moreover, this strategy allows a better control of the structure of the final material and offers an easier shape modelling.Materials resulting from nanobuilding blocks can be used in different application domains such as catalysts, 6,7 varnishes and adhesives; 8 or marginally in two-terminal circuit device nano-applications 9,10 or non-volatile random access memory. 11 Most nanobuilding units are nanocrystals that can be classified according to their one-, two-or three-dimensionalities 12 such as tubes, wires, plates, 13-15 multipods, crosses, stars. 16 These different dimensionalities lead to materials with various morphologies such as films, 17 fibres, 18,19 mushroom-like particles, 20 spheres, 21,22 or monoliths. 23 In order to control the self-assembly process of nanoobjects for the elaboration of hierarchically organized materials, several techniques have been i...

Antibiotic eluting clay mineral (Laponite®) for wound healing application: an in vitro study

“…XRD results showed that basal reflection corresponding to the c lattice plane (d001), shifted to lower angels. This shift is attributed to the molecular interactions between mafenide and Laponite structure as reported by other study [21]. Although pristine mafenide powder is crystalline, as shown in the inset of Fig.…”

“…4a, blue line), illustrated a 2-step mass loss. The first step was around 90°C, which is attributed to the loss of physio-adsorbed water and the second step (around 850°C) is due to dehydroxylation of the structural layers of the clay [21]. While Laponite was quite stable up to 850°C, mafenide decomposed at the temperatures ranged between 200 and 500°C with almost 98 % weight loss (Fig.…”

“…In the Lap/Maf spectrum, the intensity of Laponite is stronger than mafenide and almost dominated the spectrum. The intense and sharp peak positioned at 1,000 cm -1 is attributed to the Si-O-Si bending vibration of Laponite [21], which is present in both pristine Laponite and Lap/Maf spectra. Mafenide has specific peaks at the range of 1,100-1,580 cm -1 wavelengths, whereas Laponite does not show any peak in this range (shown in the box on Lap/Maf spectra).…”

Novel Insights on Swelling and Dehydration of Laponite

“…More recently these anisotropic nanoparticles were considered as building basic units of multilayered photonic crystals [3]. Lap and surface modified Lap can be used for adsorption of dyes [4], surfactants and biomolecules, to reinforce biopolymers based films [5] or as effective drug carrier [6].…”

Re‐Dispersible 1D and 2D Nanoparticle Solid Powders without any Surfactant

“…Only the basal spacing peak moves from 7.35° to 6.16°, and all peaks are wider and weaker, because of the loose gelation structure. These phenomena illustrate that there is a heterogeneous layer stacking distribution probably as a result of the polydisperse distribution of Laponite in water . The SEM image (Figure c) of S‐Laponite shows the powder has a network structure and is assembled by the elementary disc crystals in a face‐to‐edge mode, which can weaken the interaction among discs and improve the dispersion of S‐Laponite in solvents.…”