ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSymmetry and defects in the CM phase of polymeric liquid crystalsHelmut R. Brand, P. E. Cladis, Harald PleinerCite this: Macromolecules 1992, 25, 26, 7223–7226Publication Date (Print):December 1, 1992Publication History Published online1 May 2002Published inissue 1 December 1992https://pubs.acs.org/doi/10.1021/ma00052a025https://doi.org/10.1021/ma00052a025research-articleACS PublicationsRequest reuse permissionsArticle...

We present a coupled two-fluid model for hydrodynamic surface modes on concentrated polymer solutions and gels. This is used to investigate such in the limit of strong coupling. The mode dispersion relation ω(k) structure factor S(k,ω) thermally induced fluctuations are derived this materials with general constitutive η(ω). argue existence several types modes, including Rayleigh elastic waves, capillary overdamped resulting from viscous dissipation solvent as well diffusion case solutions....

The nonlinear hydrodynamic equations for biaxial discotics with two broken translational symmetries (which have been identified experimentally very recently) are presented and the structure of excitations is considered. For rotational symmetries, owing to existence preferred axes, gradient free energy, representing a generalization Frank energy nematic liquid crystals, given derived. As striking result set three commutator-type relations reflecting anholomomity variables characterizing found...

We present the derivation of macroscopic equations for uniaxial ferrogels. In addition to usual hydrodynamic variables gels we introduce magnetization and relative rotations between network as variables. The introduced here a system with magnetic degrees freedom are analog by de Gennes in nematic elastomers director respect elastomeric network. These give rise large number static well dynamic effects due their coupling magnetization, strain field, density linear momentum. A few them...

The linearized hydrodynamics of spin motion in $A$-$^{3}\mathrm{He}$ is derived from the broken symmetries and thermodynamics alone. Spin diffusion modes are obtained without with spin-orbit coupling an external magnetic field.

We investigate dynamic magneto-optic effects in a ferromagnetic nematic liquid crystal experimentally and theoretically. Experimentally we measure the magnetization phase difference of transmitted light when an external magnetic field is applied. As model study coupled dynamics magnetization, M, director field, n, associated with crystalline orientational order. demonstrate that studied macroscopic behavior reveals importance cross-coupling between M n. The experimental data are used to...

We derive the complete set of macroscopic dynamic equations for ferrogels under an external magnetic field, including magnetization as independent degree freedom. The magnetoelasticity comes in form magnetostriction and through part Maxwell stress. Various couplings elastic freedom with field are found. discuss static elongation, shear deformations, modified sound spectrum presence field.

In the limit of infinite yield time for stresses, hydrodynamic equations viscoelastic, non-Newtonian liquids such as polymer melts must reduce to that solids. This piece information suffices uniquely determine nonlinear convective derivative, an ongoing point contention in rheology literature.

Thermal convection in binary liquid mixtures is investigated the limit where solutal diffusivity weak, but separation ratio large. Representative examples are colloidal suspensions such as ferrofluids. With a grain size being large on molecular length scales, particle mobility extremely small, allowing to disregard concentration dynamics most cases. However, this simplification does not hold for thermal convection: Due pronounced Soret effect of these materials combination with considerable...

We study the deterministic spin dynamics of an anisotropic magnetic particle in presence a field with constant longitudinal and time-dependent transverse component using Landau-Lifshitz-Gilbert equation. characterize dynamical behavior system through calculation Lyapunov exponents, Poincaré sections, bifurcation diagrams, Fourier power spectra. In particular we explore positivity largest exponent as function magnitude frequency applied its direction respect to main anisotropy axis particle....

The fluctuations of a horizontal fluid layer heated from below are analyzed, based on the hydrodynamic equations in Boussinesq approximation including thermodynamic fluctuating forces. By means formalism, recently developed by Martin, Rose, and Siggia, system coupled nonlinear integral is derived for set correlation functions, response appropriate ’’self−energies.’’ solved approximately several steps simplification. In addition to results an earlier linear theory, our cover narrow region...

Hydrodynamics of complex fluids with multiple order parameters is governed by a set dynamic equations many material constants, which only some are easily measurable. We present unique example magneto-optic coupling in ferromagnetic nematic liquid, long-range orientational liquid crystalline molecules accompanied magnetic nanoplatelets. investigate the dynamics response experimentally and theoretically find out that it significantly affected dissipative cross-coupling between parameters. The...

Motivated by the experimentally observed shear-induced destabilization and reorientation of smectic-A-like systems, we consider an extended formulation smectic-A hydrodynamics. We include both, smectic layering (via layer displacement u normal p(circ)) director n(circ) underlying nematic order in our macroscopic hydrodynamic description allow both directions to differ nonequilibrium situations. In homeotropically aligned sample does couple applied simple shear, whereas stays unchanged. This...

We point out for the first time that classical Lehmann effect, which arises when a temperature gradient is applied parallel to helical axis of cholesteric droplet, not only due dynamic cross-coupling between director orientation and temperature, but has also static contribution. In addition it demonstrated analogous effect in an external homogeneous electric field purely dynamic, concentration mixture contribution, whereas density there are cross-couplings involved. The latter possibility...

The hydrodynamic equations describing the macroscopic behaviour of chiral smectic C are presented. To derive these nature spontaneously broken continuous symmetries is considered and their consequences for hydrodynamics pointed out. Similarities differences to achiral cholesteric liquid crystals investigated in some detail. influence ferroelectricity on hydrodynamics, particular structure normal modes, discussed. In two appendices we study flexoelectric electrohydrodynamic effects various...

We discuss theoretically the possibility of a spontaneous nematic splay phase for polar nematogens. This novel liquid crystal is similar to cholesteric chiral nematogens (spontaneous twist), since it spatially inhomogeneous and breaks translational symmetry, blue phases, contains defects. In contrast analogous defect structures in nonpolar crystals, which are enforced by special boundary conditions only, thermodynamically stable ground state some temperature interval.

The linearized hydrodynamic theory of 3He-B is derived from thermodynamics by symmetry arguments alone. Spin waves are obtained as Goldstone modes the broken spin-orbit symmetry. Their spectrum omega (k) analysed and found to be isotropic, phonon-like with a damping approximately k2. Effects weak magnetic dipole interaction an applied external field calculated. former leads mixing one transverse mode longitudinal gap in which large NMR shift characteristic 3He-B.