Ein neuer Einblick in die Form der Molek�le der Zellulose und der Polymerisate

Κatz, J. R.; Samwel, P. J. P.

doi:10.1007/bf01505044

Cited by 23 publications

(2 citation statements)

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“…Creation of new functional materials would be possible from this natural resource if the cellulose suprastructure can be controlled at the nanoscale using the LB technique. The spreading behavior of cellulose acetate and O -ethylcellulose on a water surface at the air−water interface was investigated more than 60 years ago. − Monolayers of cellulose derivatives as a material were, however, not transferred on substrates until Kawaguchi et al succeeded in preparing multilayers of cellulose esters by the horizontal lifting method . Since then, LB monolayers of cellulose ethers have been extensively studied with respect to properties as LB films. − Among them there were only a few reports about the fine surface structure and thickness of LB monolayers. , Considering O -alkylcellulose derivatives as polymer substrates, it has not been investigated that distribution of alkyl side chains may have an effect on monolayer morphology, although the relationship between surface morphology and length of alkyl side chains has been investigated. ,, Since physical properties of monolayers are generally correlated with the fine structure including the super- and supramolecular structures, it is of importance to investigate the detailed information of the LB monolayer structures.…”

Section: Introductionmentioning

confidence: 99%

Compression Behavior of Langmuir−Blodgett Monolayers of Regioselectively Substituted Cellulose Ethers with Long Alkyl Side Chains

et al. 2005

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Regioselectively substituted alkylcellulose ethers having long alkyl side chains, 6-O- (6C18), 2,3-di-O- (23C18), and tri-O-octadecyl-cellulose (triC18) were successfully synthesized. The key step of these syntheses was removal of the residual alkylation reagent by an isothermal crystallization procedure to isolate and purify the compounds, since a physical entanglement between the long alkyl side chains in the cellulose derivatives and the reagent had caused difficulty in obtaining the purified derivatives. After the monolayers from these cellulose ethers were fabricated on a water surface, they were deposited on substrates by a vertical dipping method to be Langmuir-Blodgett (LB) monolayers. During the compression process of each monolayer, a surface pressure (pi)-area (A) isotherm behaved in a different way. Atomic force microscopy (AFM) was employed to interpret changes of the surface topography of the obtained LB monolayers depending on the surface pressure. The compressed 23C18 LB monolayer was observed to be more homogeneous than other samples. On the basis of the LB monolayer thickness estimated by AFM as well as X-ray reflection measurements, the 23C18 LB monolayer was assumed to possibly possess the vertical arrangement of an up-ordering of all the alkyl side chains on the individual glucose ring against the water surface. In other words, with increase in the surface pressure, the usual conformation of a 2(1) screw of cellulose backbone may be changed into an unusual conformation with a certain phi-psi dihedral angle resulting in 1-fold axis without a symmetry element. These results suggest that the formation of such compressed LB monolayers was strongly influenced by the hydrophobic interaction among the distribution of the long alkyl side chains in the anhydroglucose unit and further lack of inter- and/or intramolecular hydrogen bonds engaged in cellulose ethers, and as a result, those effects may even change the main chain conformation.

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Section: Introductionmentioning

confidence: 99%

Compression Behavior of Langmuir−Blodgett Monolayers of Regioselectively Substituted Cellulose Ethers with Long Alkyl Side Chains

et al. 2005

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“…The monolayer formation of synthetic polymers on water was first described by Katz and Samwell in 1928 using poly(vinyl acetate) and poly(methyl acrylate). Since then, a great deal of data have been accumulated on the monolayer formation (Langmuir monolayer) of preformed polymers on water and their spreading behavior .…”

Section: Introductionmentioning

confidence: 99%

Monolayer Formation of Hydrophobic Polysilane on Water through Hybridization with Liquid Crystal Molecules

2001

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The monolayer formation of a hydrophobic polymer, poly(dihexylsilane) (PDHS), on the water surface was performed for the first time through cospreading with a liquid crystal molecule, 4′-pentyl-4-cyanobiphenyl (5CB). The spread monolayer formation of PDHS was confirmed by surface pressure-area (π-A) isotherm measurements, Brewster angle microscopy (BAM), atomic force microscopy (AFM), and UV-visible absorption spectroscopy. The cospread film of PDHS and 5CB on water exhibited isotherms giving a new sharp pressure increase attributable to the hybridization of PDHS/5CB. The lift-off area corresponding to this pressure increase was in exact proportion to the mixing ratio (R ) [Si unit of PDHS]/[5CB]). BAM revealed a highly homogeneous feature of the hybrid monolayers on water at the lift-off area of the PDHS/ 5CB hybrid film. The AFM images of these hybrid monolayers transferred onto mica indicated that the thickness of the spread PDHS film on the 5CB monolayer ranges from 1 to 1.5 nm. Most probably, the molecularly spread PDHS backbone is positioned on top of the 5CB monolayer. The hybrid films could be transferred onto a solid substrate. UV-visible absorption spectra showed that the Si main chain of PDHS adopts only a helical-gauche (disordered) conformation on both water and a quartz substrate, which shows a sharp contrast with that of the bulk film. On the solid substrate, a preferential orientation of the Si chain was observed in the lifting direction depending on the surface pressure applied for deposition.

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Ultrathin films of cellulose on silicon wafers

et al. 1993

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The first preparation of thin films of cellulose itself is reported. Cellulose exhibits excellent wetting behavior, is extremely stable against oxidation and other chemical degradation and in thin‐film form would have a number of applications. The method involves the preparation of LB films of trimethylcellulose (see Figure) and the in situ conversion of these thin films on silicon substrates to cellulose.

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Ein neuer Einblick in die Form der Molek�le der Zellulose und der Polymerisate

Cited by 23 publications

References 1 publication

Compression Behavior of Langmuir−Blodgett Monolayers of Regioselectively Substituted Cellulose Ethers with Long Alkyl Side Chains

Compression Behavior of Langmuir−Blodgett Monolayers of Regioselectively Substituted Cellulose Ethers with Long Alkyl Side Chains

Monolayer Formation of Hydrophobic Polysilane on Water through Hybridization with Liquid Crystal Molecules

Ultrathin films of cellulose on silicon wafers

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