Cyclopentasiloxane, PEG/PPG-18/18 Dimethicone

Li, Fangfang, et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015, 470, 290-296.

PEG/PPG-18/18 dimethicone in cyclopentasiloxane serves as a lipophilic emulsifier, combining polyethylene glycol, polypropylene glycol, and a dimethylsiloxane branch. This study utilized a one-step emulsification method to produce W/Si/W multiple emulsions, integrating key ingredients such as polydimethylsiloxane (PDMS), PEG/PPG-18/18 dimethicone in cyclopentasiloxane, Bis-PEG/PPG-20/5 dimethicone, and methoxy PEG/PPG-25/4 dimethicone. The research evaluated various formulation parameters, including the oil-water ratio, magnesium sulfate, and xanthan gum, while also assessing the stability and rheological characteristics of the multiple emulsions.
Key Findings
· The ideal multiple emulsion structure was achieved with an oil-to-aqueous phase weight ratio of 1:8, stabilized by 0.005 mol/L magnesium sulfate in the external aqueous phase and 0.03 g of xanthan gum in the internal aqueous phase. These W/Si/W multiple emulsions displayed shear-thinning behavior akin to simple emulsions, yet also exhibited yield stress and a consistent viscosity range.
· As strain increased, both the W/Si/W multiple emulsion and the simple emulsion transitioned from viscoelastic to elastic behavior; however, the W/Si/W multiple emulsion demonstrated greater resistance to external forces and moderate elasticity. Additionally, over time, the W/Si/W multiple emulsions experienced a decrease in droplet size.

Li, Zhi, et al. Surface Science and Adhesion in Cosmetics, 2021, 543-584.

This work uses silicone oil-based long-lasting foundations as a research model to explore the key factors that affect the adhesion of such products to the skin. Among them, a film of MQ/silicone polyether binary blend can be formed after pouring the mixed solution onto the surface and evaporating the solvent. The most common silicone polyether is PEG/PPG-18/18 dimethicone (about 10% in cyclopentasiloxane), and only about 1 wt% of PEG/PPG18/18 dimethicone active ingredients are required to achieve high water content (about 80 wt%) and cold processing.
Key Findings
· For binary blends of MQ resin and PEG/PPG-18/18, in which the proportion of MQ resin is low, the viscosity increases steadily with the increase of MQ resin content, reaching a maximum value at 50 wt% MQ resin content in the binary mixture. If the MQ resin content is further increased to above 50 wt%, the film tack decreases significantly.
· The ratio of MQ resin to silicone polyether (SPE) also controls the film surface free energy and flexibility. Both the sebum and water contact angles on MQ and PEG/PPG-18/18 polydimethylsiloxane films at different MQ to SPE ratios are highly dependent on the MQ/SPE ratio. When the MQ/SPE ratio is below 4:6, the water contact angle of the film is above 110°. When the MQ resin content in the blend exceeds 50 wt% (i.e., the MQ/SPE ratio exceeds 1:1), the water contact angle drops below 110° and remains constant until the MQ resin content is as high as 80 wt%. This phenomenon can be explained by the effect of surface roughness or polarity.