Alkylpolyglycosides are versatile, mild and environmentally friendly surfactants derived from starch and fatty alcohol Renowned for their high tolerance of ionic strength, alkylpolyglycosides are the only class of nonionics that will provide wetting, interfacial tension reduction, and emulsification properties to these systems absent the presence of other classes of surfactants or hydrotroping agents. This property makes them especially valuable when considering how to couple together today's multicomponent pesticide products with disparate properties as where one component is water-soluble and others are oil soluble. The utility is further heightened when it is remembered that both water soluble and oil soluble active ingredients can have their efficacy potentiated by nonionic surfactants. Complex combinations of adjuvant chemistry have also recently entered the marketplace which require tolerance of high ionic strength.
Foam is a property exhibited by most nonionic surfactants, alkylpolyglycosides included. A limited number of agricultural applications benefit from foam but for most formulators using these products the challenge is to control the foam whatever source it comes from. A number of chemical approaches have been investigated and those persons familiar with the chemistry of nonionic surfactants will recognize the similarity to strategies employed with traditional nonionics based on alcohol or alkylarylphenol ethoxylates. The alkypolyglycoside can be based on a low molecular weight fatty alcohol, the degree of polymerization can be extended or truncated and the hydroxyl groups can be functionalized. None of these modifications are without impact on the same properties that attracted us to these surfactants initially and the impact is not always positive.
The focus of the present work is not on structural modification. It is to compare the effectiveness of a range of coformulants and foam control agents available to the agricultural formulator working with alkylpolyglycoside surfactants. Foam control agents based on fluorochemistry, silicone chemistry, hydrocarbons, fatty alcohols and polymeric defoaming surfactant are compared with each other in the alkylpolyglycoside environment. Relative effectiveness of foam control is assessed and recommendations offered to guide formulation development.