Flocculation and Coalescence of Oil-in-Water Poly(dimethylsiloxane) Emulsions

Koh, Andrew Yew Chiang; Gillies, Graeme; Gore, Jeff; Saunders, Brian R.

doi:10.1006/jcis.2000.6909

Cited by 64 publications

(55 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, the formation of stable emulsions in aqueous solution is a tricky process due to the high viscosities of typical PDMS precursors and the low surface energy of PDMS. [11][12][13] As a consequence, PDMS precursor droplets tend to coalesce or aggregate, especially during the high-temperature curing step needed for converting these into cross-linked drops. [12] Coalescence is defined as the process by which an emulsion basically breaks and then the system separates into macroscopic phases.…”

Section: Introductionmentioning

confidence: 99%

Encapsulated PDMS Microspheres with Reactive Handles

González

et al. 2014

Macro Materials & Eng

View full text Add to dashboard Cite

Cured poly(dimethyl siloxane) microspheres are prepared by an emulsion polymerization reaction of silicone droplets in a continuous aqueous phase. The commonly used PDMS elastomer, Sylgard 184 from Dow Corning, is used as the dispersed phase. PDMS is polymerized and cross-linked by reacting vinyl end-terminated poly(dimethyl siloxane) oligomers with dimethylmethylhydrogen siloxane cross-linkers via the hydrosilylation reaction using platinum catalyst and heat. Weight ratios of 10:1, 20:1, and 25:1 of the PDMS mixtures are used and emulsified in water using two water-soluble surfactants as stabilizers (sodium dodecyl sulphate and polyvinylalcohol). The temperature is subsequently increased to accelerate the rate of cross-linking and prevent the prepolymer droplets from coalescing. The particle size distribution of cured PDMS microspheres is determined by Mastersizer (laser diffraction). Finally, cured PDMS microspheres are coated with poly(methyl methacrylate) using a chemical process (solvent evaporation technique). Three solvents are used in three different experiments: dichloromethane, tetrahydrofuran, and acetone. The composition and morphology of the cured PDMS microspheres and PMMA coated cured PDMS microspheres are characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy in attenuated-total-reflection mode, optical microscopy, and thermogravimetric analysis. Curing profiles of PDMS elastomer with different ratios between the silicone elastomer base and the silicone elastomer curing agent are obtained. The reactivity of cured PDMS microspheres and PMMA coated cured PDMS microspheres are measured by rheology to evaluate the efficiency of the PMMA coating.

show abstract

Section: Introductionmentioning

confidence: 99%

Encapsulated PDMS Microspheres with Reactive Handles

González

et al. 2014

Macro Materials & Eng

View full text Add to dashboard Cite

show abstract

“…The effect of additives (e.g., electrolyte and surfactants) on the stability of O/W emulsions has been studied by our group (11,12) and others (1,13). It is well established that O/W emulsions flocculate (and may coalesce) in the presence of added electrolyte due to the screening of electrostatic charge (in the case of ionic surfactants) or dehydration/salting out of the surfactant (in the case of nonionic surfactants) (1)(2)(3).…”

Section: Introductionmentioning

confidence: 99%

The Role of Added Electrolyte in the Stabilization of Inverse Emulsions

Kent

Saunders

2001

Journal of Colloid and Interface Science

Self Cite

View full text Add to dashboard Cite

“…In contrast, the value of is equal to 2 for a flattened liquid film between two equisized drops. The values of the Hamaker constants A o for the organic liquids (Vincent, 1973) and the effective Hamaker constants A m corresponding to the water-organic liquid systems obtained from A m =( A o − √ A w ) 2 used by Koh et al (2000) are listed in Table 1. The value of the Hamaker constant for water A w is 3.7 × 10 −20 J (Vincent, 1973).…”

Section: Resultsmentioning

confidence: 99%