Understanding surface science to manufacture quality cosmetics

September 17, 2018

A research team, affiliated with UNIST has examined the rates of liquid penetration on rough or patterned surfaces, especially those with pores or cavities. Their findings provide important insights into the development of everyday products, including cosmetics, paints, as well as industrial applications, like enhanced oil recovery.

This study has been jointly led by Professor Dong Woog Lee and his research team in the School of Energy and Chemical Engineering at UNIST and a research team in the University of California, Santa Barbara. Published online in the July 19th issue of the Proceedings of the National Academy of Sciences (PNAS), the study identifies five variables that control the cavity-filling (wetting transition) rates, required for liquids to penetrate into the cavities.

In the study, Professor Lee fabricated silicon wafers with cylindrical cavities of different geometries. After immersing them in bulk water, they observed the details of, and the rates associated with, water penetration into the cavities from the bulk, using bright-field and confocal fluorescence microscopy. Cylindrical cavities are like skin pores with narrow entrance and specious interior. The cavity filling generally progresses when bulk water is spread above a hydrophilic, reentrant cavity. As described in "Wetting Transition from the Cassie-Baxter State to Wenzel State", the liquid droplet that sits on top of the textured surface with trapped air underneath will be completely absorbed by the rough surface cavities.

Their findings revealed that the cavity-filling rates are affected by the following variables: (i) the intrinsic contact angle, (ii) the concentration of dissolved air in the bulk water phase, (iii) the liquid volatility that determines the rate of capillary condensation inside the cavities, (iv) the types of surfactants, and (v) the cavity geometry.

"Our results can used in the manufacture of special-purpose cosmetic products," says Professor Lee. "For instance, pore minimizing face primers and facial cleansers that remove sebum need to reduce the amount of dissolved air, so that they can penetrate into the pores quickly."

On the other hand, beauty products, like sunscreens should be designed to protect the skin from harmful sun, while preventing pores clogging. Because, clogged pores hinder the skin's function of breathing or exchange of carbon dioxide and then cause further irritation, pimples, and blemished areas on your skin. In this case, it is better to reduce volatility and increase the amount of dissolved air in the cosmetic products, as opposed to facial cleansers.

"This knowledge of how cavities under bulk water are filled and what variables control the rate of filling can provide insights into the engineering of temporarily or permanently superhydrophobic surfaces, and the designing and manufacturing of various products that are applied to rough, textured, or patterned surfaces," says Professor Lee. "Many of the fundamental insights gained can also be applied to other liquids (e.g., oils), contact angles, and cavities or pores of different dimensions or geometries."
-end-
This study has been supported by the National Research Foundation of Korea (NRF) grant, funded by the Ministry of Science and ICT.

Journal Reference

Dongjin Seo et al., "Rates of cavity filling by liquids," PNAS (2018).

Ulsan National Institute of Science and Technology(UNIST)

Related Cavities Articles from Brightsurf:

The presence of resonating cavities above sunspots has been confirmed
An international team of researchers, led by the Instituto de Astrofísica de Canarias (IAC), has confirmed the existence of resonant cavities above sunspots.

HIV alone not a risk factor for cavities in children
Recent studies indicate HIV infection heightens the risk of dental cavities - but a Rutgers researcher has found evidence that the risk of cavities comes not from HIV itself but from a weakened immune system, which could be caused by other diseases.

How the giant sequoia protects itself
A three-dimensional network of fibers makes the bark resistant to fire and rock fall.

Bacteria in Chinese pickles can prevent cavities -- Ben-Gurion University study
Prof. Ariel Kushmaro of the BGU Avram and Stella Goldstein-Goren Department of Biotechnology Engineering and the Chinese research team evaluated 14 different types of Sichuan pickles from southwest China.

Diabolical points in coupled active cavities with quantum emitters
Diabolical points (DPs) introduce ways to study topological phase and peculiar energy dispersion.

Tree cavities for wild honeybees
The forests in Europe provide habitat for around 80,000 colonies of wild honeybees.

Vapor drives a liquid-solid transition in a molecular system
The reversible switching of macrocyclic molecules between a liquid and a solid phase upon exposure to vapor has been reported in the Journal of the American Chemical Society by researchers at Kanazawa University.

Machine-learning research at OSU unlocking molecular cages' energy-saving potential
Nanosized cages may play a big role in reducing energy consumption in science and industry, and machine-learning research aims to accelerate the deployment of these remarkable molecules.

Understanding surface science to manufacture quality cosmetics
A team of researchers, affiliated with South Korea's Ulsan National Institute of Science and Technology (UNIST) has identified variables that control the cavity-filling rates, required for liquids to penetrate into the cavities.

Bio-inspired materials decrease drag for liquids
Tiny nature-inspired cavities that trap air can stop liquids from sticking to surfaces without the need for coatings.

Read More: Cavities News and Cavities Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.