Fine tuning the structural colours of photonic nanosheet suspensions by polymer doping

Abstract

Aqueous suspensions of nanosheets are readily obtained by exfoliating low-dimensional mineral compounds like H3Sb3P2O14. The nanosheets self-organize, at low concentration, into a periodic stack of membranes, i.e. a lamellar liquid-crystalline...

Repulsive Osmotic Delamination: 1D Dissolution of 2D Materials

“…Unlike traditional structural colors, this is dynamic and can be tuned by numerous stimuli like pH, [63b] temperature, [63b] ionic strength of solution, [91a] or adsorption of a polymer. [92] This unique liquid mesophase can be solidified by applying a hydrogel matrix and the resulting nanocomposites are capable of a chromomechanical response. [93] When this unique mesophase is structured into a single domain Bragg stack, the separation between nanosheets is governed by the balance between electrostatic repulsion and van der Waals interactions.…”

Do Aqueous Suspensions of Smectite Clays Form a Smectic Liquid-Crystalline Phase?

“…A sketch of the system is given in Figure . Following our previous work, we may contemplate a balance between van der Waals attraction and electrostatic repulsion, leading to the following osmotic pressure between two charged lamellae in the colloidal accordion “A”: ,, normalΠ A ∼ 8 normalk B normalT nobreak0em0.25em⁢ exp ( − d λ D ) π l normalB λ D 2 − 20 B h 2 d 6 …”

“…28−30 Interestingly, the stability of the lamellar phase in these systems extends to very low concentrations, resulting in lamellar periods comparable to the wavelengths of visible light and therefore leading to photonic properties. 27,28,31,32 However, LC phases more ordered than the nematic phase, such as the lamellar or columnar LC phases, have never been clearly evidenced in clay suspensions.…”

“…Indeed, as early as 1938, Irving Langmuir reported that aqueous clay suspensions can form a birefringent phase where the nanosheets have orientational order, in addition to the usual isotropic phase (Figure a) and in contrast with it . Some 60 years later, the nature of this orientational order was compared to that of lyotropic liquid crystals (LC), but the observation of an LC phase, at thermodynamic equilibrium, in suspensions of synthetic laponite and natural montmorillonite clays, was hampered by their strong tendency to form gels. , The clear-cut discovery of a nematic LC phase (Figure b) was only reported in 2006 when it was observed in aqueous suspensions of natural nontronite clays, a little later with beidellite clay, and more recently with synthetic hectorite and the microporous layered silicate ilerite. − Meanwhile, the smectic (i.e., lamellar) LC phase was reported for aqueous suspensions of other kinds of mineral compounds: synthetic phosphatoantimonate, niobate, and titanate nanosheets (Figure c). − Interestingly, the stability of the lamellar phase in these systems extends to very low concentrations, resulting in lamellar periods comparable to the wavelengths of visible light and therefore leading to photonic properties. ,,, However, LC phases more ordered than the nematic phase, such as the lamellar or columnar LC phases, have never been clearly evidenced in clay suspensions.…”

Nacre-inspired layered composite gels with broad tunable mechanical strength and structural color for stress visualization

“…The sonamed photonic LCs exhibit structural colors. [24][25][26][27][28][29] However, in contrast to the high fraction of CaCO 3 nanoplates in nacre shells, the fraction of nanosheets in photonic LCs is rather low. 30 Such a low fraction makes the as-prepared structuralcolored gels weak and fragile.…”