Phase separation and folding in swelled nematoelastic films

Abstract

We explore reshaping of nematoelastic films upon imbibing an isotropic solvent under conditions when isotropic and nematic phases coexist. The structure of the interphase boundary is computed taking into account the optimal nematic orientation governed by interaction of gradients of the nematic order parameter and solvent concentration. This structure determines the effective line tension of the boundary. We further compute equilibrium shapes of deformed thin sheets and cylindrical and spherical shells with the rectilinear or circular shape of the boundary between nematic and isotropic domains. A differential expansion or contraction near this boundary generates a folding pattern spreading out into the bulk of both phases. The hierarchical ordering of this pattern is most pronounced on a cylindrical shell.

Programmable filaments and textiles

“…(11), though the respective analytical expressions are far more involved than Eq. (17). The resulting change of ψ and rotation of the orientation angle of the basis over the length of the filament are shown in Fig.…”

“…Textiles incorporating Janus filaments comprising driven and passive sectors [16] (Fig. 1b) provide far more freedom of creating a variety of shapes than single filaments limited by their single dimension or sheets constrained by the continuity requirements that often lead to creation of sharp edges at locations of topological defects of the order parameter field or at sharp fronts between domains with different properties that may readily arise in the course of actuation [17]. Moreover, gliding and bending freedom at nodes of a woven fabric allow for a greater flexibility compared with 3D-printed grids [18].…”

Coupled swelling and nematic reordering in liquid crystal gels

“…where we have modeled the aforementioned dilution effect as a solvent concentration-dependent shift 15,16,24 in the characteristic temperature T s , which is related to the transition temperature, as will be discussed in Section 2.3, in the context of homogeneous equilibrium states. Here, A o is a characteristic value for the strength of the nematic interactions, T sd ξ is the value of T s for the dry LCE and f is an increasing function of φ d such that f (1) = 1.…”

“…Previous theoretical and experimental reports have mainly focused on LCEs, while those regarding LCGs have essentially studied equilibrium problems 3,[12][13][14][15][16] . In particular, Cheewaruangroj and Terentjev 15 have modeled the equilibrium phase separation in stretched nematic gels by combining anisotropic Gaussian elasticity 17,18 with Flory-Huggins mixing energy 19 , without accounting for the energy of nematic interactions.…”

“…In such a model the nematicisotropic transition is accounted for via a prescribed dependence of the order degree on temperature, which may be recovered by fitting experimental data. The study of equilibrium phase separation in nematic gels was recently resumed in the context of nemato-elastic shells by Zakharov and Pismen 16 , who extended the previous model with a nematic energy.…”