Foaming of Oils: Effect of Poly(dimethylsiloxanes) and Silica Nanoparticles

Abstract

Foaming of oils often confronts researchers in food, cosmetics, and petrochemical industries. Destabilization or stabilization of nonaqueous foams is fundamentally crucial for process control and product quality. Antifoams can be a useful method to control excessive foams. Nonetheless, the foaming mechanisms and the selection criteria of the most common antifoam, poly(dimethylsiloxane) (PDMS) oils, are not thoroughly discussed. The study of inorganic colloidal particles as foam stabilizers has drawn particular attention over the past years practically and academically, yet only a small part of literature focuses on nonaqueous foams. For these reasons, we have studied the effects of PDMS oils and silica nanoparticles on the foaming of oils. We find that the performance of silicone oils as crude oil antifoams is firmly related to PDMS viscosity and crude oil composition presumably because the solubilization of PDMS oils in hydrocarbons reduces with increasing viscosity of the polymers and the hydrocarbons. The findings also illustrate that nanoparticle hydrophobicity and concentration are the primary factors for the foam stabilization effect.

3D Printing of a Polydimethylsiloxane/Polytetrafluoroethylene Composite Elastomer and its Application in a Triboelectric Nanogenerator

“…Mixing these components lead to translucent viscous ink. The surface tension of PDMS (∼19.7 mN·m –1 at 20 °C) is slightly smaller than that of PTFE (∼23.9 mN·m –1 at 20 °C), so the PDMS precursor mixture can wet the PTFE well. After a long time of agitation, the PTFE micropowder was dispersed in the PDMS precursor mixture uniformly, and no phase-separation was observed after the ink was stored at room temperature for 5 h.…”

Foaming and antifoaming in non-aqueous liquids

“…This allows the measurement of additional foam stability metrics such as the air-release fraction of the liquid. This test is commonly used to study non-aqueous lubricant [7,9,11,14], crude oil [15][16][17][18], hydrocarbon fuel and edible oil foams [19].…”

“…Examples of particle stabilized non-aqueous foams include dichlorodimethylsilane (DCDMS)-modified amorphous silica or organo-modified Laponite clay nanoparticle stabilized glycerine or ethylene glycol foams [13], and OTFE particle (agglomerated oligomers of tetrafluoroethylene particle) stabilized perfluorostyrene/divinylbenzene mixture foams [77]. Silica nanoparticles are also known to strongly stabilize crude oil foams above a critical hydrophobicity [16]. Further information on particle stabilization can be found in reviews by Fameau and Saint-Jalmes [73], and Binks et al [76].…”

Precise Synthesis of Poly(dimethylsiloxane) Copolymers through C–H Bond-Activated Macroinitiators via Yttrium-Mediated Group Transfer Polymerization and Ring-Opening Polymerization

“…The high bond strength guarantees thermal stability and renders silicone networks chemically inert. A prolonged Si–O bond length compared to the carbon analog of 1.64 Å, a low torsion potential, and an elevated Si–O–Si bond angle of 143° result in flexible polymer chains with low glass transition temperatures. , Moreover, PDMS is characterized by high hydrophobicity , and unprecedented surface properties ,, and is generally considered to be nontoxic. , The applications of PDMS-based materials are diverse, ranging from antifoaming agents and medicinal uses , to the application in soft lithography. , In addition, copolymer combinations of PDMS and hydrophilic counterparts were reported. Blends of PDMS and PDMS–polyethylene glycol (PEG) copolymers prevented the adsorption of proteins on the respective surface by reducing its hydrophobicity .…”

“…2,3 Moreover, PDMS is characterized by high hydrophobicity 4,5 and unprecedented surface properties 2,3,6 and is generally considered to be nontoxic. 4,7 The applications of PDMS-based materials are diverse, ranging from antifoam-ing agents 8 and medicinal uses 9,10 to the application in soft lithography. 11,12 In addition, copolymer combinations of PDMS and hydrophilic counterparts were reported.…”