Polymer curing assisted formation of optically visible sub-micron blisters of multilayer graphene for local strain engineering

Abstract

The local or global straining techniques are used to modulate the electronic, vibrational and optical properties of the two-dimensional (2D) materials. However, manipulating the physical properties of a 2D material under a local strain is comparatively more challenging. In this work, we demonstrate an easy and efficient polymer curing assisted technique for the formation of optically visible multilayer Graphene (MLG) blisters of different shapes and sizes. The detailed spectroscopic and morphological analyses have been employed for exploring the dynamics of the confined matter inside the sub-micron blisters, which confirms that the confined matter inside the blister is liquid (water). From further analyses, we find the nonlinear elastic plate model as an acceptable model under certain limits for the mechanical analyses of the MLG blisters over the (poly)vinyl alcohol (PVA) polymer film to estimate the MLG-substrate interfacial adhesion energy and confinement pressure inside the blisters. The findings open new pathways for exploiting the technique for the formation of sub-micron blisters of the 2D materials for local strain-engineering applications, as well as the temperature-controlled release of the confined matter.

Hoop compression driven instabilities in spontaneously formed multilayer graphene blisters over a polymeric substrate

“…Graphene is a mechanically robust two-dimensional (2D) material in terms of its remarkably high bendability (flexibility), elasticity, and strain-bearing capacity, which is capable of forming blisters through the confinement of different kinds of matter such as liquid, gas, nanoparticles, etc at the graphene/substrate interface [1,2]. The blisters on the surface of a 2D material like graphene offer local strain-sites with altered physical properties, and also help in probing its adhesion mechanics, which show huge potentiality for fundamental research as well as practical applications in flexible and tunable electronics, optoelectronics and nanophotonics [3][4][5][6][7][8][9][10][11][12]. Furthermore, the properties of the 2D material can be manipulated by engineering the size and the shape-profiles of the blisters [13].…”

Viscous fingering instabilities in spontaneously formed blisters of MoS2 multilayers

“…We analyzed our previous experimental ndings on the PVAcuring-induced blistering of MLG akes 3,9 and observed that the conventional PVA-curing-induced blistering process results in 2D material blisters of lower h/s with a stable and regular interface whereas the cold mist adsorption-assisted blistering process results in the blisters of larger h/s with a complex interface. We further investigated the PVA-curing-induced blistering of MoS 2 akes under different synthesis and processing conditions to nd the crucial parameter that is directly connected to the synthesis and processing conditions used in the experiment, whether it be the conventional or cold mist adsorption-assisted blistering process.…”

“…We further investigated the PVA-curing-induced blistering of MoS 2 flakes under different synthesis and processing conditions to find the crucial parameter that is directly connected to the synthesis and processing conditions used in the experiment, whether it be the conventional or cold mist adsorption-assisted blistering process. M. Pandey et al 9 found that multilayered graphene blisters, formed spontaneously through the conventional PVA-curing-induced blistering process, follow the elastic plate model, which satisfies the condition h / τ ≲ 1.5, owing to significant bending rigidity of the multilayered flakes having minimal interlayer slippage. We find this observation to be also valid for multilayered MoS 2 blisters formed through the same blistering process.…”

“…1,47 However, the level of interlayer sliding is more prominent (i) during the collapse of the blister due to the phase-transition of the confined matter, which gives rise to the tent-like shape of the blister, and also (ii) during the ice-water adsorption-assisted PVA-curing-induced blistering due to the ultralubricated interface resulting from the wetting. 3 The interfacial adhesion energy density ( Γ ) of the PVA-supported MoS 2 flakes consisting of N layers can be estimated using the equation: 9 where E 2D = Eτ is the 2D elastic stiffness of the 2D flake, τ = Nt is the thickness of the 2D flake, N is the number of layers, t is the thickness of the monolayer, E is the in-plane elastic modulus of the 2D material, is the effective bending stiffness, is the constant prefactor, ν is Poisson's ratio, γ w is the surface tension of water = 72 mN m −1 , θ m is the water contact angle with the 2D flake, and θ s is the water contact angle with the substrate. For MoS 2 blisters over the PVA substrate, we use the following parameters: 9,24,48,49 E = 270 GPa, t = 0.65 nm, ν = 0.29, θ m = 69°, θ s = 51°.…”

“…[1][2][3][4] The 2D material blisters offer local strain sites with altered physical properties. [5][6][7][8][9] Knowing the physics and chemistry underlying the intended [10][11][12] or spontaneous formation 3,[13][14][15] of blisters is extremely important for the utilization or removal of 2D material blisters. 16,17 It has also been demonstrated that the blisters of direct band gap semiconductors (e.g.…”