Liquid crystalline complexes of an azo‐containing surfactomesogen with oppositely charged polyelectrolytes

Abstract

A triethyl-ammonium functionalized 4-nitro-4 0 -alkoxy azobenzene mesogen with a 10-carbon spacer (azo10Q, a ' 'surfactomesogen' ') was complexed in equimolar proportions to a variety of oppositely charged polyelectrolytes, and studied by differential scanning calorimetry (DSC), polarizing optical microscopy, and X-ray diffraction. The complexation generates a single-layer smectic A mesophase over a very wide temperature range from a surfactomesogen that, alone, melts directly to the isotropic phase. The clearing temperatures, ranging from 130 to 190 8C and generally higher than the melting point of azo10Q, are dependent on the nature of the polyelectrolyte as well as its molecular weight. In contrast, a prominent glass transition near ambient temperature appears to be independent of molecular weight, but varies somewhat with the type of polyelectrolyte. A second T g -like transition of much lower intensity is detectable at higher temperatures (generally above 100 8C), and, with literature support, is tentatively attributed to nanophase separation involving sublayer planes in the lamellar packing structure. A series of nonequimolar complexes was also investigated, and it was found that, with decreasing azo10Q content, the clearing temperature viewed by DSC decreases rapidly in intensity (and somewhat in temperature) and then disappears although birefringence remains, whereas the lower glass transition increases rapidly in temperature to finally merge with the upper one.

Single Molecule Studies on Dynamics in Liquid Crystals

“…For example, vertical structure resolution within LC films could be obtained from films on tailored reflecting substrates [ 52 ] using temperature controlled setups. One the other hand, extension of LC-approved SM methods to other LC materials and configurations, such as free standing LC films [ 70 ] and single-layer smectics [ 71 ], is featured to extend the insight on such materials. Moreover, further development of SM methods will increase the research possibilities.…”

Solvent Manipulation of Liquid Crystal Order and Other Properties in Azo‐Containing Surfactomesogen/Poly(styrene sulfonate) Complexes

“…[25] The latter pattern, reported a number of times in the literature, is generally ascribed to extinction of the first-order peak by an additional plane of symmetry in the electron density profile along the lamellar normal. [18,25,[33][34][35][36][37][38][39] Assuming that the most intense diffraction peak for the polar-tailed complexes is indeed a second-order reflection, it was observed that all of the liquid crystalline complexes had a periodicity close to a single extended molecular length of the repeat unit (considering that the ion pairs can be arranged either parallel or perpendicular to the molecular long axis), thus indicating effectively single-layer SmA phases.…”

“…[25] Finally, it is worth mentioning that the present study was inspired by some apparent irreproducibility in the intensity pattern of the low angle XRD region during initial investigations of O 2 N-O10Q/PSS. [18,25] Complexes Exposed to H 2 O Although the complexes are insoluble in water, their ion content can lead to water absorption. The equilibrium absorption in the complexes exposed to 100% RH, measured gravimetrically over a period of 2 weeks and generally found to be constant within a day, was found to range from 15 to 25 wt.-%, corresponding to 7-10 H 2 O molecules per repeat unit.…”

“…In supramolecular LCs, ionic bonding is often used to bind together two oppositely charged components, [1][2][3][4][5][6] as an alternative to the very popular hydrogen-bonding interaction. [2][3][4]7,8] This is the case for the construction of supramolecular side-chain LC polymers achieved by the ionic complexation of polyelectrolytes with oppositely charged surfactants, [9][10][11][12][13] with surfactomesogens (SMs), [1,[14][15][16][17][18][19] or with other ionic molecules such as ionic dyes. [6,[20][21][22][23] The ionic bond is attractive, in part, for its more robust and thermally stable character compared to the hydrogen bond in situations where these characteristics are desirable.…”

Interaction of photosensitive surfactant with DNA and poly acrylic acid

“…The resulting materials are highly structured and show a variety of liquid crystalline phases. [26][27][28][29][30][31][32] When the complexes are processed from organic solvent to thin films, and then exposed to light, they can be used to create surface relief gratings, 28,30 generate optical anisotropy, 29 or can be applied as aligning layers for liquid crystals. 28 One promising PSCs application is the development of non-viral gene delivery vectors based on DNA.…”