Crystalline membrane morphology beyond polyhedra

Abstract

Elastic crystalline membranes exhibit a buckling transition from sphere to polyhedron. However, their morphologies are restricted to convex polyhedra and are difficult to externally control. Here, we study morphological changes of closed crystalline membrane of super-paramagnetic particles. The competition of magnetic dipole-dipole interactions with the elasticity of this magnetoelastic membrane leads to concave morphologies. Interestingly, as the magnetic field strength increases, the symmetry of the buckled membrane decreases from 5-fold to 3-fold, to 2-fold and, finally, to 1fold rotational symmetry. This gives the ability to switch the membrane morphology between convex and concave shapes with specific symmetry and provides promising applications for membrane shape control in the design of actuatable micro-containers for targeted delivery systems. arXiv:1903.00818v1 [cond-mat.soft]

Janus magnetoelastic membrane swimmers

“…Recall that the morphology transition of closed magnetoelastic membranes is a result of the competition between the elasticity and the magnetic dipole-dipole interactions. 56 In our study, passive fluid particles are able to penetrate the magnetoelastic membrane of hemisphere A from both inside and outside, triggering the changes in the volume enclosed by the shell. Hence, the morphology transition of our penetrable Janus swimmers becomes a result of the interplay of the elasticity with the magnetic dipole-dipole interactions as well as the hydrodynamic interactions.…”

“…We remain ω = 0.5 τ −1 (∼1760 s −1 ), and all production simulations run at least 1.7 × 10 6 timesteps (1.7 × 10 3 τ ). Similar to the FvK number, the relative strength between magnetic energy and bending energy can be characterized by a dimensionless quantity called magnetoelastic parameter, 56,83 where is the magnetic modulus defined in the continuum limit and M̃ = (1/4)( μ 0 /4π)(9 μ 2 / r eq 3 )(2/3). The magnetoelastic parameter of the magnetoelastic membrane with reference parameters is Γ = 336 when the strength of the induced magnetic dipole is μ = 1.36 in units of .…”

“…We remain o = 0.5 t À1 (B1760 s À1 ), and all production simulations run at least 1.7 Â 10 6 timesteps (1.7 Â 10 3 t). Similar to the FvK number, the relative strength between magnetic energy and bending energy can be characterized by a dimensionless quantity called magnetoelastic parameter, 56,83…”

“…[44][45][46] Such irregular body deformations can also be realized by nonlinear elastic buckling of crystalline membranes under many conditions. [47][48][49][50][51][52][53][54][55][56] For example, deformable capsules under pressure changes adapt irregular morphologies. [57][58][59] Moreover, the self-assembled crystalline membranes, like the shells of viruses, generally buckle into shapes with icosahedral symmetry.…”

Designing Surface Charge Patterns for Shape Control of Deformable Nanoparticles

“…Computational studies of deformations of patchy, flexible NPs have been largely limited to the use of elastic surface inhomogeneities, yield-ing, for example, regular polyhedra, buckled conformations, and collapsed bowl-like structures [31][32][33]. Alternatively, theoretical efforts have focused on revealing shape transitions in homogeneously-charged flexible nanostructures as a function of ionic conditions [34][35][36][37] and understanding shape manipulation in uncharged elastic shells driven by topological defects, compression, or magnetic forces [38][39][40]. Despite emerging capabilities for synthesizing charge-patterned NPs and colloids [3,41,42] and the prevalent use of electrostatic control to induce changes in material assembly behavior [13,43], a thorough understanding of the interplay between electrostatic and elastic energies for shape manipulation in charge-patterned flexible NPs is lacking [44].…”