Thermoreversible gelation in binary mixtures of poly(di-n-alkylsilanes) and aromatic solvents

Lenk, T. J.; Siemens, R.; Hallmark, V. M.; Miller, R. D.; Rabolt, John F.

doi:10.1021/ma00005a041

Cited by 5 publications

(3 citation statements)

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“…Actually, the thermo-responsive organogelation of poly(di-n-alkylsilane)s may be related to an ability to produce two types of block-like structures (7 3 helical and trans-zigzag). 11 Similarly, a mixture of two ammonium amphiphiles undergoes microphase separation. 19 Triple-chain ammonium amphiphiles with fluorocarbons cannot mix with the corresponding amphiphiles with hydrocarbon in bilayer membranes in water, and spontaneously undergoes phase separation in the same membrane films.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, poly(di-n-butylsilane) and poly(di-n-pentylsilane) can form thermo-responsive organogels in aromatic solvents through a heating-cooling process. 11 These organogels are essentially composed of two phases, 7 3 helical and trans-zigzag chain phases, presumably due to the formation of noncovalent crosslinks with the help of cooperative van der Waals interchain side chain packing interactions.…”

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confidence: 99%

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Polysilane Organogel with Hierarchical Structures Formed by Weak Intra-/Inter-chain Si/FC and van der Waals Interactions

Kawabe

Naito

Fujiki

2008

Polym J

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A semiflexible polysilane copolymer bearing 3,3,3-trifluoropropyl and n-decyl side chains formed an organogel in nonpolar organic solvents. Weak Si/FC interchain/intrachain interactions were formed between the Si main chain and fluoropropyl side chain, and acted as noncovalent crosslinks. Long alkyl (n-decyl) groups acted as solvophilic moieties that effectively absorbed and retained organic solvent molecules. Furthermore, the relatively rigid main chain was also important for the gelation ability of the material. The existence of Si/FC interchain interactions was first demonstrated by careful IR measurement and analysis using a model silane molecule. Hierarchical structures at the meso-and nano-scale levels were successfully characterized by AFM, cryo-HR-TEM, IR, and 19 F{ 29 Si}-NOE NMR experiments.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Polysilane Organogel with Hierarchical Structures Formed by Weak Intra-/Inter-chain Si/FC and van der Waals Interactions

Kawabe

Naito

Fujiki

2008

Polym J

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“…Gelation in organic solvents has so far been observed for a large variety of compounds, viz., lecithins, cholesterol derivatives, peptides, two-component gelling agents, calixarenes, semifluorinated n -alkanes 21 or silanes, phenols, urea compounds, tetra-alkylammonium salts, and glucosamides . Despite the fact that a relatively broad range of compounds display gelation, no rules of thumb for the design of such compounds have been given in the literature.…”

Section: Introductionmentioning

confidence: 99%

Organogels from Carbohydrate Amphiphiles

1999

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Gluconamides can be easily functionalized to give a variety of compounds that form organogels with a high viscosity. N-n-octyl-D-gluconamide-6-benzoate gelates a large variety of organic solvents, including 1,2-xylene, chloroform, ethyl acetate, and ethanol, to form gels which are, in some cases, stable even above the boiling point of the pure solvent. The 2-methoxy, 6-imidazolyl, 6-acetyl, and 6-cyclohexanoyl derivatives also show gelation, but the 2,4;3,5-dimethylene-protected derivatives do not. Detailed 1 H NMR, IR, and X-ray powder diffraction studies reveal that the molecules of most gelators are packed in a head-to-tail fashion. If there is, however, the possibility to form interlayer hydrogen bonds, as in the case of N-n-octyl-D-gluconamide or N-n-octyl-D-gluconamide-6-(3pyridyl carboxylate), the molecules are packed head-to-head. Some gluconamides, e.g., those with aliphatic substituents, express their molecular chirality in the supramolecular structures, whereas others, in particular those containing a large aromatic substituent on carbon atom C 6 , yield nonchiral aggregates, probably due to interfering π-π stacking interactions of the substituents. DSC experiments show that the formation of the gels is an entropy-driven process.

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Excitation dependence of Raman spectra of various polydialkylsilane conformations and σ–σ conjugation

Bukalov

Leites

Magdanurov

et al. 2003

Journal of Organometallic Chemistry

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Thermoreversible gelation in binary mixtures of poly(di-n-alkylsilanes) and aromatic solvents

Cited by 5 publications

References 2 publications

Polysilane Organogel with Hierarchical Structures Formed by Weak Intra-/Inter-chain Si/FC and van der Waals Interactions

Polysilane Organogel with Hierarchical Structures Formed by Weak Intra-/Inter-chain Si/FC and van der Waals Interactions

Organogels from Carbohydrate Amphiphiles

Excitation dependence of Raman spectra of various polydialkylsilane conformations and σ–σ conjugation

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