Creation and structural comparison of ultrathin film assemblies: transferred freely suspended films and Langmuir-Blodgett films of liquid crystals

Decher, Gero; Maclennan, Joseph E.; Sohling, Ulrich; Reibel, J.

doi:10.1016/0040-6090(92)90325-6

Cited by 42 publications

(19 citation statements)

References 7 publications

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“…Out of these techniques, polyelectrolyte multilayer (PEM) coatings offer great potential as an easy, non-covalent modification of biomaterial surfaces. Such multilayer thin films are prepared by exploiting a facile, yet elegant technique called the layer-by-layer (LBL) method, which was introduced by Decher et al in 1990 s. [4] Principally, this powerful technique is based on the alternating adsorption of oppositely charged polyelectrolytes onto a charged substrate. PEM characteristics like thickness, viscoelasticity, topography, surface charge, and wettability are dependent on the adsorbed polyelectrolytes, i.e., intrinsic properties (molar mass, charge density, chain stiffness) as well as on the suspending solution properties (pH value, ionic strength, temperature) and also the type of substrate.…”

Section: Introductionmentioning

confidence: 99%

Tuning Cell Adhesion and Growth on Biomimetic Polyelectrolyte Multilayers by Variation of pH During Layer‐by‐Layer Assembly

Aggarwal

Altgärde²,

Svedhem³

et al. 2013

Macromolecular Bioscience

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Polyelectrolyte multilayers of chitosan and heparin are assembled on glass where heparin is applied at pH = 4, 9 and 4 during the formation of the first layers followed by pH = 9 at the last steps (denoted pH 4 + 9). Measurements of wetting properties, layer mass, and topography show that multilayers formed at pH = 4 are thicker, contain more water and have a smoother surface compared to those prepared at pH = 9 while the pH = 4 + 9 multilayers expressed intermediate properties. pH = 9 multilayers are more cell adhesive and support growth of C2C12 cells better than pH = 4 ones. However, pH 4 + 9 conditions improve the bioactivity to a similar level of pH = 9 layers. Multilayers prepared using pH 4 + 9 conditions form thick enough layers that may allow efficient loading of bioactive molecules.

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Section: Introductionmentioning

confidence: 99%

Tuning Cell Adhesion and Growth on Biomimetic Polyelectrolyte Multilayers by Variation of pH During Layer‐by‐Layer Assembly

Aggarwal

Altgärde²,

Svedhem³

et al. 2013

Macromolecular Bioscience

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“…The transitions of the FS-films of polymer 1 to their crystalline phase was successful in almost all cases. This is in contrast to FS-films of low molecular weight compounds, which hardly can be cooled to crystalline phases [8]. Possible explanations for this might either be the relatively large film thicknesses or a stabilizing effect of the polymer backbones in addition to the intermesogenic forces.…”

Section: Freely-suspended Films Of the Homopolymer (Polymer 1)mentioning

confidence: 84%

“…From the electron diffraction pattern a layer thickness of 3 8 k 3 A was obtained in contrast to the calculated value of 26. 8 A for side chain and backbone (fully extended conformation). These values suggest a not fully extended flexible spacer and/or an interdigitated layer structure which is also found in smectic A phases of low molecular weight alkyl-and alkoxycyanobiphenyls.…”

Section: Transferred Freely-suspended Films Of Lc-polymersmentioning

confidence: 99%

“…In order to preserve the orientation but simultaneously to increase the stability, a method for transferring freely-suspended films on solid substrates was developed [ 6 , 71. In the case of an amphiphilic biphenyl liquid-crystal a direct comparison of the properties of transferred freely-suspended (TFS) and LB-films was carried out and resulted in a higher temperature stability of the former [8]. Further investigations of both film types with atomic force microscopy (AFM) illustrated remarkable differences in film morphologies and defects [9].…”

Section: Introductionmentioning

confidence: 99%

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Freely‐Suspended and Transferred Freely‐Suspended Films of Polymeric Liquid Crystals

Decher

Reibel

Honig

et al. 1993

Ber Bunsenges Phys Chem

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Freely‐suspended (FS) liquid‐crystal (LC) films of a polymethylsiloxane homo‐ and a copolymer with different mesogenic side groups have been prepared and investigated. For both substances the preparation of the films succeeded only in the isotropic phase but the higher ordered phases were reached after cooling. The films of the homopolymer have only been obtained with thicknesses estimated to be in the pm‐range and with an unusual “Book‐Shelf” orientation of the smectic layers. In contrast, the films of the copolymer were thinner and showed a homeotropic orientation of the mesogens in the smectic A phase. Interestingly, this material exhibited a different layer spacing in film and bulk, although no differences in the phase transition temperatures could be detected within experimental error. FS‐films of the homopolymer have been transferred to solid supports. Both the FS and the transferred freely‐suspended (TFS) films of this material were particularly stable as compared to films of low molecular weight compounds.

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“…The sequentially arranged polymer layers of opposite charge interact with one another electrostatically and keep themselves in place. Decher and co‐worker developed this technique in the 1990s by consecutive adsorption of anionic and cationic polyelectrolytes to yield thin films 97–100. Subsequently, this relatively easy layer deposition method was applied to the formation of microcapsules 97, 101, 102.…”

Section: Synthetic Nanoreactorsmentioning

confidence: 99%

Selective and Responsive Nanoreactors

Renggli

Baumann

Langowska

et al. 2011

Adv Funct Materials

228

242

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Chemical reactions can be confi ned to nanoscale compartments by encapsulating catalysts in hollow nanoobjects. Such reaction compartments effectively become nanoreactors when substrate and product are exchanged between bulk solution and cavity. A key issue, thereby, is control of shell permeability. Nanoreactors exhibit selectivity and responsiveness if their shells discriminate among molecules and if access can be modulated by external triggers. Here, we review natural nanoreactors that include protein-based bacterial microcompartments, protein cages, and viruses. Artifi cial nanoreactors based on dendrimers, layer-by-layer capsules, and amphiphilic block copolymer polymersomes are also discussed. Selectivity in these nanoreactors is either due to intrinsic reactor-shell semipermeability or can be engineered using smart polymers to gate the reactors. Moreover, a rich repertoire of pores and channels are already provided in nature, e.g., in protein-based nanoreactors or in trans-membrane channel proteins. The latter can be reconstituted in polymersomes, resulting in gated vesicles. Nanoreactors hold promise for applications ranging from selective and size-constrained organic synthesis to biomedical advances (e.g., artifi cial organelles, biosensing) and as analytical tools to study reaction mechanisms.

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Creation and structural comparison of ultrathin film assemblies: transferred freely suspended films and Langmuir-Blodgett films of liquid crystals

Cited by 42 publications

References 7 publications

Tuning Cell Adhesion and Growth on Biomimetic Polyelectrolyte Multilayers by Variation of pH During Layer‐by‐Layer Assembly

Tuning Cell Adhesion and Growth on Biomimetic Polyelectrolyte Multilayers by Variation of pH During Layer‐by‐Layer Assembly

Freely‐Suspended and Transferred Freely‐Suspended Films of Polymeric Liquid Crystals

Selective and Responsive Nanoreactors

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