Redefining Poly in Alkylpolyglucosides
Properties and applications of Alkylglycoside surfactants with elongated headgroup
Conventional large-scale production of alkylglycosides (“alkylpolyglucosides”, or APGs) yields surfactants comprising headgroups with low average degree of polymerisation (Dp≤2). The term “alkylpolyglucoside” is therefore, strictly speaking, a misnomer as far as conventional technology goes. In stark contrast, ethoxylated (PEG-based) non-ionic surfactants can be produced on industrial scale with virtually any length of alkyl chain and headgroup.
Enza Biotech AB has recently shown that enzymatic technology allows for facile production of alkylglycosides with long headgroups (Dp>>2) and long alkyl chains (≥16). The present paper summarises some of the physicochemical properties of these novel surfactants. The focus of the paper is on hexadecyloctaglucoside (C16G8), which is shown to have new and unique properties of direct relevance for formulation of cosmetics and personal care products, particularly as regards wetting and dispersion of hydrophobic particles.
For the last 20-some years, alkylglycosides (often referred to as “alkylpolyglucosides”, APGs) have rapidly grown in importance to become a key class of non-ionic surfactants in cleaning, personal care, cosmetics and manifold other areas of formulated products. Conventional, industrial-scale production of alkylglycosides is based on Fischer glycosylation. (1, 2) The method is used to prepare a wide range of APGs, in an economically feasible manner and from raw materials that are completely (or at least predominantly) sourced from sustainable origins. Nevertheless, the Fischer method has important inherent drawbacks that impose strict limitations on the molecular architecture of the reactants and products. In the context of the present paper, the most important limitation pertains to the length of the head-groups and alkyl chains in the products. More specifically, for reasons of reaction kinetics and physical incompatibility of the starting materials, the average degree of polymerisation in commercial APGs is actually lower than 2. Obviously, this means that the term poly in alkylpolyglucoside is in itself a misnomer. Furthermo ...