Organosilicone surfactants as adjuvants for agrochemicals

Abstract

The literature has been reviewed and 160 references are presented to provide an overview of organosilicones as adjuvants for agrochemicals. Early studies (1973–1981) elucidated the special properties of these compounds, notably their extreme spreading and, by virtue of the exceptionally low surface tensions of their aqueous solutions, the ability to induce infiltration of spray formulations into foliage via stomata. Subsequent research at the New Zealand Forest Research Institute explored these and other properties in‐depth, and demonstrated that they enabled the herbicide glyphosate to be used as a cost‐effective alternative to 2,4,5‐T for the control of forest scrubweeds. As a result, in 1985, ‚Silwet’︁ L‐77 was the first organosilicone adjuvant to be commercialised, and various other products have subsequently been introduced. The chemistry and synthesis of these organosilicones have been detailed. A mechanistic approach has been adopted to consider the effects of the distinctive properties of organosilicones in each of the processes involved in spray application of agrochemicals. Commencing with spray formulation, the topics of foaming, hydrolytic stability and interactions with coformulants are discussed. Progressing to spray application, consideration is given to the effects of organosilicones on atomisation and impaction (wetting, adhesion/reflection, spreading, retention/run‐off), and the resultant influences on the activity of protectant agrochemicals. An assessment of the use of organosilicones with systemic agrochemicals includes examination of effects on foliar uptake, via both cuticular and stomatal pathways, and the rainfastness which the latter provides. Also considered is the physiological behaviour of organosilicones, specifically phytotoxicity and effects on translocation of active ingredients. The current and potential future use of organosilicones with herbicides, foliar nutrients, growth regulators, insecticides and fungicides is discussed, as is the specificity of their effects. Additionally, the potential application of organosilicone chemistry to adjuvant classes other than the spreader/penetrant type investigated to date is considered. Finally, the issues of registration, handling hazards, both toxicological and chemical, and environmental impact are discussed. The literature reviewed demonstrates the sound science base on which this novel class of organosilicone adjuvant chemistry rests.

Organics Characterization Of DWPF Alternative Reductant Simulants, Glycolic Acid, And Antifoam 747

“…Acid and base catalyzed hydrolytic cleavage of the silicone-oxygen bonds has been investigated [Stevens, 1993;Knoche, 1994;Sun, 1996;Nikolov, 2011] and occurs readily below a pH of 5 and above pH 9. In addition, the surfactant has been reported to degrade in neutral aqueous environment after forty days [Peng, 2009].…”

Indirect Effects of Pesticides on Natural Enemies

“…Another potential issue to be considered is that any indirect effects of pesticides on natural enemies may not necessarily be affiliated with the active ingredient but due to inert ingredients in the commercial formulation [2, [160][161][162][163][164]. It is possible that formulations such as emulsifiable concentrates (EC) and soluble powders (SP) may contain additives such as adjuvants, surfactants, solvents and/or carriers that are indirectly harmful to natural enemies [45,165].…”

Silicon-modified carbohydrate surfactants. IV. The impact of substructures on the wetting behaviour of siloxanyl-modified carbohydrate surfactants on low-energy surfaces

“…Due to this superspreading property they are extensively used as adjuvants in plant protection formulations. 2,3 The siloxane surfactants lower the surface tension of the formulations to values below 25 mN m Ϫ 1 . Even wax-covered, low-energy leaf surfaces can be wetted by these formulations.…”