Silicone polymers, especially non-ionic silicone polymers have been commonly used in personal care products for many years1. Their unique, low surface tension allows easy spreading on keratinous surfaces, such as hair and skin, and provides significant beneficial improvements in sensory properties, such as soft feel and shine. Silicone emulsions are predominantly used because they are easier to handle and formulate than silicone oil. Silicone prepared with the proper emulsifier results in a stable emulsion having a defined particle size.


The delivery of silicone to substrates directly from emulsions or from surfactantcontaining “rinse off” formulations has been studied. Deposition of silicone onto hair has been reported to be affected by the ionic charge, particle size and viscosity of the silicone oil emulsion.2,3


Polycations, such as cationic HEC, are widely used either as conditioning polymers by themselves or in conjunction with other oleaginous materials in both hair and skin care products. The deposition of cationic HEC and silicone from shampoo systems onto hair has been reported.4,5


The cationic HEC forms a coacervate (polymer-surfactant complex) upon dilution during the application and rinsing of the formulation.6 The coacervate phase separates from the bulk formulation and is deposited on the hair or skin. Insolubles, such as silicone, are entrapped in the coacervate phase and become deposited along with the polymer.


The properties of the coacervate are dependent on the surfactant system and polymer affecting the combined deposition of insoluble actives and cationic polymers onto keratinous substrates.6,7 There is no detailed study on the effect of the silicone particle size, in conjunction with polymer parameters, surfactant system, and hair type on deposition of silicone onto hair. In this study, two nonionic silicone emulsions of high molecular weight polydimethylsiloxane with different particle sizes, 0.5µm and 20µm, were evaluated with a variety of cationic HEC polymers, hair types and two surfactant systems: (A) 15.5% sodium laureth sulfate (ES-2)/2.6% disodium cocamphodiacetate (DSCADA).; and (B) 4% ammonium lauryl sulfate (ALS)/13.5% ammonium laureth sulfate (ALES)/2.6% cocamdiopropylbetaine (CAPB)/1% sodium chloride. The results indicate that optimisation of 2-in-1 shampoo formulation can be achieved by the appropriate selection of polymers in conjunction with specific silicone particle size.


Appropriate matching of polymer type and silicone particle size allows formulators to develop products with the desired aesthetic properties.


SOURCE FROM https://www.personalcaremagazine.com