Role of solvation forces in the gelation of fumed silica–alcohol suspensions

Smith, William E.; Zukoski, Charles F.

doi:10.1016/j.jcis.2006.08.021

Cited by 17 publications

(10 citation statements)

References 41 publications

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“…42,43 Gelation was found to be extremely slow due to an energetic barrier in the interparticle potential associated with solvation forces created by a layer of ethanol molecules that were hydrogen bonded to the particle surface. 42 The potential barrier can be altered through changes in the hydrogen bonding ability between the particle and solvent. In addition, FTIR spectra revealed the existence of hydrogen bonds between the surface silanol groups and the -OH group of ethanol molecules.…”

Section: Time (Days)mentioning

confidence: 99%

Direct-write assembly of silicate and borate bioactive glass scaffolds for bone repair

Deliormanlı

Rahaman

2012

Journal of the European Ceramic Society

100

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Section: Time (Days)mentioning

confidence: 99%

Direct-write assembly of silicate and borate bioactive glass scaffolds for bone repair

Deliormanlı

Rahaman

2012

Journal of the European Ceramic Society

100

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“…Due to the large surface area (50-400 m 2 g À1 ) and branching structure, fumed silica is commonly used as an effective thixotropic and thickening agent, which modifies the rheological response of dispersions. 5,6 Particularly, fumed silica is also used as an excellent emulsifier of oil and water, 7 and enables the formation of remarkably stable dispersions. 8,9 Besides, the dispersion of fumed silica in polyether liquids has been used as polymer electrolytes in rechargeable lithium batteries.…”

Section: Introductionmentioning

confidence: 99%

A rheological study on temperature dependent microstructural changes of fumed silica gels in dodecane

Wang

Yang

et al. 2012

Soft Matter

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The effect of temperature on colloid systems of hydrophobic and hydrophilic fumed silica in dodecane was investigated mainly by means of dynamic rheology. Dynamic frequency sweeps showed frequency-independent elastic modulus (G 0 ), indicating the presence of gel networks in both dispersions. Dynamic temperature sweeps consisting of a heating and cooling cycle were also conducted. For the hydrophobic fumed silica gel, G 0 slowly decreased with rising temperature owing to the increased particle mobility and decreased strength of hydrogen bonds due to the higher thermal energy. However, the hydrophilic fumed silica gel showed a rather unusual temperature dependent behavior involving a transition temperature (T c ) and an irreversible increase in G 0 during the cooling cycle. This unusual behavior was believed to be related to the restructuring of nanoparticle chain aggregates (NCA) of fumed silica in gels as also revealed by FTIR results. Further analysis on this behavior showed that elevated temperature tended to increase the fractal dimension (D f ) of aggregates, resulting in more compact NCAs and thereby a denser gel network with a higher G 0 . These results suggest that temperature is an important external variable that can be regarded as an optional simple way to tailor the viscoelastic properties and to control the microstructure of colloidal systems such as fumed silica dispersions in dodecane. II. Experimental section 1. Materials and sample preparationThe colloidal nanoparticle employed here was fumed silica whose native properties have been studied in detail by Gun'ko et al. [23][24][25]

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“…In fact, the role played by the fractal aggregation of fumed silica in gelation of a range of solvent has been extensively investigated and is believed to be caused due to the hydrogen bonding mediated by the silanol groups (Si-OH) present on the particle surface. 23,24,40 The fractal aggregate formation is much stronger in non-polar solvents that are not capable of forming hydrogen bonding hence, promoting more particle-particle interactions. 40,41 In contrast, hydrophobic fumed silica (where the silanol surface groups are modied with hydrophobic moieties) tend to show a weak gelling behaviour because of the decrease in the hydrogen bonding sites.…”

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confidence: 99%

“…23,24,40 The fractal aggregate formation is much stronger in non-polar solvents that are not capable of forming hydrogen bonding hence, promoting more particle-particle interactions. 40,41 In contrast, hydrophobic fumed silica (where the silanol surface groups are modied with hydrophobic moieties) tend to show a weak gelling behaviour because of the decrease in the hydrogen bonding sites. 24 To verify this, the gelation of oil by hydrophobic fumed silica (A972) was studied through rheological measurements and compared to A150 (Fig.…”

mentioning

confidence: 99%