In-Depth Insights into the Key Steps of Delamination of Charged 2D Nanomaterials

Abstract

ABSTRACT:Delamination is a key step to obtain individual layers from inorganic layered materials needed for fundamental studies and applications. For layered van-der-Waals materials like graphene the adhesion forces are small allowing for mechanical exfoliation, whereas for ionic layered materials like layered silicates the energy to separate adjacent layers is considerably higher. Quite counter intuitively, we show for a synthetic layered silicate (Na 0.5 -hectorite) that a scalable and quantitative delamination by simple hydration is possible for high and correlated. This is indicated by fulfilling the classical Hansen-Verlet and Lindeman criteria for melting. We provide insight into the requirements for layer separation and controlling the layer distances for a broad range of materials and outline an important pathway for the integration of layers into devices for advanced applications.

Role of initial precursors on the liquid-crystalline phase behavior of synthetic aluminogermanate imogolite nanotubes

“…The formation of LC phases in dispersions of clay particles has attracted a considerable amount of attention in recent years (Miyamoto and Nakato, 2012;Paineau et al, 2013), probably because colloidal behavior of clay dispersions act as a key parameter for coating, thickening and thixotropic additives in industrial purposes (Carretero and Pozo, 2009;Harvey and Lagaly, 2013). LC phase transition has been observed not only in aqueous dispersions of exfoliated nontronite (Michot et al, 2006(Michot et al, , 2008(Michot et al, , 2013, beidellite (Paineau et al, 2009) or fluorohectorite (Hemmen et al, 2009;Miyamoto et al, 2010;Rosenfeldt et al, 2016) nanosheets but also in dispersions of clay nanorods or nanotubes, like sepiolite (Woolston and van Duijneveldt, 2015;Zhang and van Duijneveldt, 2006), halloysite (Luo et al, 2013) and imogolite (Amara et al, 2013, p. 201;Kajiwara et al, 1986;Levitz et al, 2008).…”

Colloidal Stability of Imogolite Nanotube Dispersions: A Phase Diagram Study

“…[6][7][8][9][10][11][12][13][14] These charged clay nanosheets exhibit a wide variety of states (isotropic sols, liquid-crystal phases, repulsive and attractive arrested phases, flocs and aggregated sediments) depending not only on the size of the clay particles or the effect of charge location, but also on the ionic strength IS of the solution ( ∑ , where the sum performed over all types 'i' of ions of the solution, with concentration ci and with charge zi, is simply equal to the concentration of monovalent ions here), the valence and hydration properties of ions in the suspension. [15][16][17][18][19][20] Compared to this large body of literature, there is surprisingly few works dealing with the colloidal stability of one-dimensional clay particles such as sepiolite nanorods 21 or halloysite nanotubes. 22 It might be related to the challenges of stabilizing in aqueous media this type of anisometric objects that remain stable for only few hours.…”

Clay nanolayer encapsulation, evolving from origins of life to future technologies

“…The delamination and subsequent exfoliation of clay nanolayers, i.e. the two-step process of physically obtaining the situation depicted in Figure 4a starting from the situation depicted in Figures 4b and 4c is most often performed in aqueous suspension, and in this case, the two-step process is referred to as attractive crystalline and osmotic swelling respectively [32][33][34]. This delamination process can be promoted by sonification or by temperature ( Fig.…”