Increasing hair manageability via silicone moisture control

Why is it then that a humid or rainy day – full of moisture in the air – concerns so many? To keep hair manageable, moisture must be controlled. A study was recently conducted to determine the best silicone for moisture control. With a general knowledge of silicone, the anatomy of hair and the results uncovered during the study, determining methods to treat hair to increase manageability becomes easier to establish.

Silicone background

It was in the 1930s that a shortage of natural rubber and the demand for more stable insulating materials sparked the development of silicone. During World War II, silicone became even more popular commercially for military application and, after the war ended, non-military uses for silicone became crucial for the survival of the industry. Although silicone has become prevalent in many industries during the ensuing decades, the healthcare industry and, more specifically, the personal care industry has particularly benefited. Silicone’s biocompatibility is an important attribute that lends itself well to consumer products. Because it is non-toxic and non-allergenic, silicone can be utilised in products applied from head to toe. Molecularly speaking, silicone is comprised of repeating siloxane units, Si-O, with substituent groups attached to the open valences of the silicon atom. Having no carbon in the backbone, these repeating siloxane units are often referred to as a polysiloxane polymer. Figure 1 shows the typical structure. The siloxane backbone can be formulated with various substituent groups incorporated onto the polymer backbone as well. Typical substituent groups include methyl, phenyl and trifluoropropyl. In addition, the siloxane backbone allows these various groups to be added in several ways. For example, the substituent groups can all be of the same molecule, like a dimethylpolysiloxane polymer, or the polymer can have a combination of different substituent groups such as a diphenyldimethylpolysiloxane copolymer. This particular copolymer, shown in Figure 2, is of interest for the study conducted. As we will see, a correlation exists between higher phenyl concentrations and lower moisture permeability. When choosing a material for personal care applications, material performance is an important consideration. Beneficial characteristics of silicones for personal care applications arise from fundamental chemical and physical properties of the polymer chains and organic substituent groups. For instance, how well a material spreads is due to its viscoelastic properties, which are directly related to its molecular architecture. Silicones are spreadable because the siloxane backbone is extremely flexible and viscosities of typical siloxane polymers are much lower than hydrocarbons of the same molecular weights. The nature of the organic substituent groups also has an effect. The ability to alter the substituent groups of the siloxane backbone makes silicone extremely dynamic. Non-polar organic groups, such as methyl groups, create hydrophobic surfaces, while polar groups, such as polyether, create hydrophilic materials.1