Small Angle Neutron Scattering on Nematic Lyotropic Liquid Crystals

Herbst, Leandra; Hoffmann, H.; Kalus, J.; Reizlein, K.; Schmelzer, U.; Ibel, K.

doi:10.1002/bbpc.19850891009

Cited by 37 publications

(7 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For neutrons the scattering length densities for tail and head groups are both nearly equal and different from go-The diameter of N(CH3)4 is around 0.54 nm. 4 With this value we expect for neutrons to see a thickness of the lamellae of «3.7 nm, a value which is comparable to the measured one.…”

Section: Results For the Isotropic Phasesupporting

confidence: 73%

See 1 more Smart Citation

Structure of the Isotropic, Nematic, and Lamellar Phase of a Solution of Tetramethylammonium Perfluorononanoate in D2O

Froeba¹,

Kalus²

1995

J. Phys. Chem.

Self Cite

View full text Add to dashboard Cite

A 30% by weight solution of tetramethylammonium perfluorononanoate in D20 (TMAHFN; CsF17COON-(CH3)4) is in a lamellar state below 33 "C. In this state the repeat distance and the thickness of the perfluoronated part of the micellar lamellae are around 7.11 and 2.14 nm, respectively. In the presence of a strong magnetic field of 2.0 T a slow reduction of the sample temperature from 40 "C (isotropic phase) via 34 "C (nematic phase) down to 25 "C gives a strong alignment of the nematic and lamellar liquid crystalline phases. By small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) experiments, an order parameter, the mean scattering length density across the lamellae, the structure factor related to the one-dimensionality of the lamellar phase, and information about the perforation of the lamellae could be extracted. A model taking into account all+these effects quantitatively describes the experimental scattering intensity distribution in reciprocal space (Q space) accessible in our experimental setup. Furthermore, for the nematic phase we can extract detailed data on the anisotropic correlation between neighboring discotic micelles. The scattering intensity distribution of the isotropic phase can be described quite satisfactorily again assuming diskiike micelles, where the perfluoronated part of the micelle has a thickness of 2.4 nm and a radius of about 3.0 nm.

show abstract

Section: Results For the Isotropic Phasesupporting

confidence: 73%

“…For AV a value of 0.533 nm3 was used. 4 For the calculation of the form factor we analyzed two models.…”

Section: Results For the Isotropic Phasementioning

confidence: 99%

Structure of the Isotropic, Nematic, and Lamellar Phase of a Solution of Tetramethylammonium Perfluorononanoate in D2O

Froeba¹,

Kalus²

1995

J. Phys. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Tiddy et al. − observed the formation of a hexagonal H 1 phase, an intermediate phase, and a lamellar L α phase for ammonium and lithium perfluorooctanoate. A nematic N D phase and lamellar L α phase were found for cesium perfluorooctanoate and ammonium perfluorononanoate observed the existence of a cubic phase for perfluoroheptanoic acid, its salts, and ethoxylated amides.…”

Section: Introductionmentioning

confidence: 96%

Branched Fluorinated Nonionic Y-Shaped Surfactants. Effect of Molecular Geometry on Liquid Crystalline Phase Behavior

et al. 1996

View full text Add to dashboard Cite

The synthesis of branched partially fluorinated nonionic Y-shaped surfactants, with the general formula C F nC2N(EmM)2, where C F n denotes fluorinated alkyl chain F(CF2)n with n ) 4-10, C2 is C2H2, and EmM is oligooxyethylene monomethyl ether with m ) 2, 3, and their hydrocarbon analogs Cn+2N(EmM)2 (Cn equals hydrocarbon chain) is described. These surfactants are synthesized to analyze the influence of the fluorinated alkyl chain on the packing effects to amphiphilic layers in a binary surfactant/water system. The lyotropic phase behavior of these surfactants is investigated by polarizing microscopy. The liquid crystalline (LC) phase polymorphism of the fluorinated C F nC2N(E3M)2 surfactants strongly changes with n from hexagonal H1 phase (n ) 6) to lamellar LR phase (n ) 10). In contrast to other Y-shaped hydrocarbon oligooxyethylene surfactants CnG(EmM)2 (where G denotes a glycerol unit) which form only cubic I1 and H1 phases for n ) 12-16 and m ) 3-5, the phase behavior of the C F nC2N(EmM)2 surfactant/water systems shows a remarkable change in the LC phase polymorphism (from H1 to LR phase) with n and m. Compared to hydrocarbon surfactants these results distinctly confirm the influence of more rigid fluorinated alkyl chain on the phase behavior.

show abstract

“…Sometimes it was found that a discotic nematic phase existed intermediate between the isotropic and lamellar phases . The lack of cubic and hexagonal phases is explained by the aggregation of the disk-shaped micelles, which already form a lamellar phase at small concentrations . Recently, we have shown that perfluorooctadecanoic acid forms monodispere thin disklike micelles at small concentrations (10 -3 to 10 -4 mol/L) .…”

Section: Resultsmentioning

confidence: 99%

Colloidal Complexes of Perfluorooctadecanoic Acid with Cationic Copolymers

Thünemann

Lochhaas

1999

Langmuir

View full text Add to dashboard Cite

Five solid complexes of poly[(diallyldimethylammonium chloride)-co-(N-methyl-N-vinylacetamide)] with perfluorooctadecanoic acid were prepared at 1:1 stoichiometry. Remarkably low surface energies, as determined by contact angle measurements, were attributed to a strong enrichment of complex surfaces with CF3 groups. By increasing of the charge density of the polyelectrolyte, the surface energy decreased from 14 to 9 mN/m. As determined by small-angle X-ray scattering, the solid complexes show a mesomorphic structure. A columnar liquid crystalline-like structure with columns consisting of stacks of disklike micelles, two-dimensionally ordered in hexagonal arrays, is suggested. The thermal stability of the structures is explained by Coulomb interactions between diallyldimethylammonium groups and carboxylate ions * To whom correspondence should be addressed.

show abstract

Small Angle Neutron Scattering on Nematic Lyotropic Liquid Crystals

Cited by 37 publications

References 15 publications

Structure of the Isotropic, Nematic, and Lamellar Phase of a Solution of Tetramethylammonium Perfluorononanoate in D2O

Structure of the Isotropic, Nematic, and Lamellar Phase of a Solution of Tetramethylammonium Perfluorononanoate in D2O

Branched Fluorinated Nonionic Y-Shaped Surfactants. Effect of Molecular Geometry on Liquid Crystalline Phase Behavior

Colloidal Complexes of Perfluorooctadecanoic Acid with Cationic Copolymers

Contact Info

Product

Resources

About