Alkyl Polyglycosides in Personal Care Products

 Over the past decade, the development of raw materials for personal care products has progressed in three main areas:

（1）      mildness and care for the skin

（2）      high quality standards by minimization of by-products and trace impurities

（3）      ecological compatibility.

Official regulations and consumer needs are increasingly stimulating innovative developments that follow the principles of process and product sustainability. One aspect of this principle is the production of alkyl glycosides from vegetable oils and carbohydrates from renewable source. The development of commercial technology requires a high level of control over raw materials, reactions and processing conditions to meet the quality requirements of modern cosmetic raw materials and to produce them at a reasonable cost. In the field of cosmetics, alkyl glucoside is a new type of surfactant with conventional non-ionic and anionic properties. To date, the largest proportion of commercial products are cleansers represented by C8-14 alkyl glycosides, which are characterized by their skin and hair care characteristics. C12-14 alkyl polyglycoside acts as an emulsifier in specific formulations and particularly in microemulsions and studying the performance of C16-18 alkyl polyglycoside as a self-emulsifying o/w base blended with fatty alcohol.

For body cleansing formulations, a new modern surfactant must have good compatibility with skin and mucous membranes. Dermatological and toxicological tests are necessary to assess the risk of a new surfactant and design most importantly to identify possible stimulation of living cells in the epidermal basal layer. In the past, this has been the basis of surfactant mildness claims. At the same time, the meaning of gentleness has changed a lot.Today, mildness is understood as the complete compatibility of surfactants with the physiology and function of human skin.

Through various dermatological and biophysical methods, the physiological effects of surfactants on the skin were studied, starting from the surface of the skin and advancing to the deeper layer of basal cells through the stratum corneum and its barrier function.At the same time, subjective sensations, such as the sensation of skin, are recorded through the language of touch and experience.

Alkyl polyglycosides with C8 to C16 alkyl chains belong to the group of very mild surfactants for body cleansing formulations. In a detailed study, the compatibility of alkyl polyglycosides was described as a function of the pure alkyl chain and the degree of polymerization.In the modified Duhring Chamber Test, C12 alkyl polyglycoside shows a relative maximum within the range of mild irritation ects whereas C8,C10 and C14,C16 alkyl polyglycoside produce lower irritation scores. This corresponds to observations with other classes of surfactants. In addition, irritation decreases slightly with increasing degree of polymerization (from DP= 1.2 to DP= 1.65).

APG products with mixed alkyl chain length have the best overall compatibility with a higher proportion of long alkyl glycosides (C12-14).They were compared by the addition of very mild hyperethoxylated alkyl ether sulphates, amphoteric glycine or amphoteric acetate, and extremely mild protein-fatty acids on collagen or wheat proteolytic substances.

The dermatological findings in the arm flex wash test show the same ranking as in the modified Duhring Chamber Test where mixed systems of standard alkyl ether sulfate and alkyl polyglycosides or amphoteric co-surfactants are investigated. However, the arm flex wash test allows better differentiation of the effects. Formation of erythema and squamation can be reduced by 20-30 D/o if around 25 °10 of SLES is replaced by alkyl polyglycoside which indicates a reduction of about 60 %. In the systematic build-up of a formulation, an optimum can be achieved by the addition of protein derivatives or amphoterics.