Auxetic nanomaterials: Recent progress and future development

Abstract

Auxetic materials (materials with negative Poisson's ratio) and nanomaterials have independently been for many years two of the most active research fields in material science. Recently, these formerly independent fields have begun to intersect in new and interesting ways due to the recent discovery of auxeticity in nanomaterials like graphene, metal nanoplates, black phosphorus, and others. Here we review the research emerging at the intersection of auxeticity and nanomaterials. We first survey the atomistic mechanisms, both intrinsic and extrinsic, that have been found, primarily through atomistic simulations, to cause auxeticity in nanomaterials. We then outline the available experimental evidence for auxetic nanomaterials. In order to lay the groundwork for future work in this exciting area, we close by discussing several future prospects as well as the current challenges in this field.

Differential Poisson’s ratio of a crystalline two-dimensional membrane

“…Nowadays, a negative Poisson's ratio is found in various materials and artificially engineered structures (see Ref. [5] for a review).…”

Composite metamaterial square grids with sign-flipping expansion coefficients leading to a type of Islamic design

“…(11), one is justified to adopt the reduced form given in the second of Eq. (13). Due to the lack of CPE data, these were converted from their bulk modulus data [57] as follows.…”

“…Their investigation provides distinctive sensing results and therefore avails a novel method to the microfluidic sensor applications by using the sample holder. Although negative material properties-such as negative Poisson's ratio [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], negative thermal expansion [23][24][25][26][27][28][29][30][31], negative compressibility [32][33][34][35][36][37] and negative moisture expansion [38][39][40]-have been investigated for a few decades due to their capability of behaving in ways that are not achievable by conventional materials, it remains that some applications may require both positive and negative properties depending on the circumstances. For this reason, a series of metamaterials in which their effective material properties can switch between positive and negative signs have been introduced.…”

A perspective on auxetic nanomaterials

“…Beginning with seminal experiments of Lakes, who demonstrated NPR in a foam structure [2], various structures and materials have been shown to exhibit the NPR phenomenon [3–15]. …”