Backbone effects on the anchoring of side-chain polymer liquid crystals

Jérôme, Bruno; Commandeur, J. M.; Jeu, Wim H. de

doi:10.1080/026782997208785

Cited by 20 publications

(20 citation statements)

References 26 publications

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“…Furthermore, planar anchoring with a vanishing perpendicular component was found in Ref. 16 . Cross polarized light microscopy data on a similar nematic liquid crystalline polymer sample 28 showed domains with different in-plane orientations ϕ and a size of approx.…”

Section: B Polarization Dependent Resonant X-ray Reflectivitymentioning

confidence: 91%

“…These films are excellent model systems to demonstrate the sensitivity of XRR to molecular orientation, as the stiff elongated side-groups tend to align parallel to each other even in bulk and take specific orientations close to interfaces 16 . Optical dichroic measurements at the free surface showed an in plane alignment of the optical axis 17 .…”

Section: Introductionmentioning

confidence: 99%

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Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

et al. 2011

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We present a technique to study depth profiles of molecular orientation in soft matter thin films with nanometer resolution. The method is based on dichroism in resonant soft X-ray reflectivity using linear s-and p-polarization. It combines the chemical sensitivity of Near-Edge X-ray Absorption Fine Structure spectroscopy to specific molecular bonds and their orientation relative to the polarization of the incident beam with the precise depth profiling capability of X-ray reflectivity. We demonstrate these capabilities on side chain liquid crystalline polymer thin films with soft X-ray reflectivity data at the carbon K edge. Optical constants of the anisotropic refractive index ellipsoid were obtained from a quantitative analysis using the Berreman formalism. For films up to 50 nm thickness we find that the degree of orientation of the long axis exhibits no depth variation and is independent of the film thickness.

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Section: B Polarization Dependent Resonant X-ray Reflectivitymentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

et al. 2011

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“…The constants in equation (1) (compare Fig. Homeotropic anchoring at an air-film surface (leading to smectic layering parallel to the interface) has been reported to be quite general for LC polymers with aliphatic chain-terminated side groups [13,14]. Homeotropic anchoring at an air-film surface (leading to smectic layering parallel to the interface) has been reported to be quite general for LC polymers with aliphatic chain-terminated side groups [13,14].…”

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confidence: 99%

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et al. 2001

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We report on the thin-film behaviour of a polyacrylate with phenyl benzoate mesogenic side groups and a narrow polydispersity. Depending on the degree of polymerisation, these polymers show a nematic, a smectic-A d , a re-entrant nematic and aC phase with a two-dimensional monoclinic lattice. X-ray reflectivity and atomic-force microscopy have been used to characterize the structure and surface morphology. The system exhibits two stable side-chain packing configurations with incommensurate spacings that can be both stabilized at a free surface. Thin films in the nematic phase show a structural dewetting induced by the growth of surface domains of theC phase. Additionally, surface-induced ripples with a nanoscale lateral period form at the air-film interface. We attribute these patterns to a coupling between the local liquid crystalline ordering of the mesogenic side groups and the surface curvature energy. PACS. 64.70.Md Transitions in liquid crystals -78.70.Ck X-ray scattering -61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures

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“…Precise control of molecular aggregation structure in thin films is therefore critical to tune functional properties. Generally, the orientation of side chains in thin film samples will be dominated by minimization condition of the interfacial free energy . Surface modification of polymer thin films by rubbing has been among the most widely used approaches to control of side chain orientation, particularly in crystal and liquid‐crystal state displays .…”

Section: Introductionmentioning

confidence: 99%

“…So far, numerous number of polymers with liquid crystalline or crystalline side chains consisting of long alkyl chains and aromatic groups have been reported. In these systems, interaction between the side chain groups and the substrate strongly affects the orientation of the side chain and may favor either vertical or parallel orientation of the side chains with respect to the substrate . Alternatively, the length of the main chain may control to alter the orientation tendency of the side chain groups, although this relationship is not currently well understood .…”

Section: Introductionmentioning

confidence: 99%

Effect of molecular weight on microcrystalline structure formation in polymer with perylenediimide side chain

Kido

Nojima

Ishige

et al. 2016

J. Polym. Sci. Part B: Polym. Phys.

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The effect of molecular weight on the molecular aggregation structure of polymers bearing a pendant perylenediimide (PDI) side chain, designated PAc12PDI, was investigated using synchrotron radiation X‐ray diffraction measurements. It was found that depending on molecular weight, either the main chain axis or the side chain axis behaves as the longitudinal axis in fiber samples and was aligned parallel to the fiber axis. A similar phenomenon is present in thin film samples, but was complicated by the additional influence of the interfacial free energy of the side chain group. Even in the case of the polymer with lower molecular weight, the face plane of PDI was found to show both parallel and perpendicular orientations to the substrate (i.e., flat‐on and edge‐on orientations). On the other hand, if the length of the main chain is sufficiently long with respect to the length of the side chain, the face plane of PDI was oriented perpendicular to the substrate, leading to an edge‐on orientation in the thin film. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2275–2283

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Backbone effects on the anchoring of side-chain polymer liquid crystals

Cited by 20 publications

References 26 publications

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

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Effect of molecular weight on microcrystalline structure formation in polymer with perylenediimide side chain

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