Cellulose nanocrystal-based emulsions and uses thereof

Abstract

This invention relates generally to cellulose nanocrystal-based emulsions that can serve as a spray adjuvant for improved agrochemical application efficiency. More particularly, the cellulose nanocrystal-based emulsions are nanocellulose-stabilized Pickering emulsions having a semi-liquid formulation of colloidal cellulose nanocrystals and biopolymers that can substitute currently used surfactants and drift reducing agents in agrochemicals. The cellulose nanocrystal-based emulsions are suitable with both water soluble and oil soluble active ingredient chemistries, and the shear characteristics of the emulsions make them suitable for oil in water-based spray applications. Droplet size distribution can be tuned by changing the ingredient concentrations, thus helping control particle drift. Moreover, a stable cross-linked network formation facilitates the entrapment and encapsulation of volatile agrochemical chemistries, thus preventing their volatilization and reducing vapor drift.

What is claimed is: 
     
         1 . A cellulose nanocrystal-based emulsion, said emulsion comprising:
 a continuous aqueous phase, comprising:
 between about 0.25% and about 3% (w/w) of a sulfonated cellulose nanocrystal; 
 between about 0.25% and about 1% (w/w) of a co-stabilizing biopolymer; and 
 up to about 3.0% (w/w) of a cationic crosslinker; and 
   a dispersed oil phase comprising a plant-based oil.   
     
     
         2 . The emulsion of  claim 1  wherein the sulfonated cellulose nanocrystal is pristine, functionalized, or a combination of both. 
     
     
         3 . The emulsion of  claim 1  wherein the co-stabilizing biopolymer is selected from the group consisting of alginate, chitosan, starch, derivatized or nanofibrillated cellulose, collagen, lignin, hydroxyapatite, cyclodextrin, guar gum, carrageenan, silk, or a combination thereof. 
     
     
         4 . The emulsion of  claim 3  wherein the co-stabilizing biopolymer is up to about 1% alginate (w/w). 
     
     
         5 . The emulsion of  claim 3  wherein the co-stabilizing biopolymer is between about 0.5% and about 3.0% nanofibrillated cellulose (w/w). 
     
     
         6 . The emulsion of  claim 1  wherein the crosslinker is a cationic salt comprising divalent or trivalent cations. 
     
     
         7 . The emulsion of  claim 6  wherein the cationic salt further comprises an alkaline metal ion or a transition metal ion. 
     
     
         8 . The emulsion of  claim 7  wherein the alkaline metal ion or the transition metal ion is selected from the group consisting of Ca 2+ , Ba 2+ , Fe 2+ , Mg 2+ , Zn 2+ , Mn 2 +, Cu 2+ , Fe 3+ , Al 3+ , Au 3+ , or a combination thereof. 
     
     
         9 . The emulsion of  claim 8  wherein the cationic crosslinker is calcium chloride (CaCl 2 ). 
     
     
         10 . The emulsion of  claim 8  wherein the cationic crosslinker is Mg 2+  or Zn 2+ . 
     
     
         11 . The emulsion of  claim 1  wherein said plant-based oil is selected from the group consisting of oleic oil, crop oil, methylated seed oil, essential oils, sunflower oil, coconut oil, canola oil, neem oil, soybean oil, cottonseed oil, or a combination thereof. 
     
     
         12 . The emulsion of  claim 11  wherein said plant-based oil is oleic acid. 
     
     
         13 . The emulsion of  claim 1  wherein said cellulose nanocrystal-based emulsion is an adjuvant for an agricultural product, a food product, a cosmetic product, a paint product, a coating product, a pharmaceutical product, or a combination thereof. 
     
     
         14 . The emulsion of  claim 13  wherein said agricultural chemical is selected from the group consisting of pesticides, fungicides, insecticides, herbicides, or a combination thereof. 
     
     
         15 . The emulsion of  claim 1  wherein said cellulose nanocrystal-based emulsion has a water-to-oil ratio of between about 70:30 v/v to about 90:10 v/v. 
     
     
         16 . A method of producing a cellulose nanocrystal-based emulsion, the method comprising the 
     
     
         1 . producing said emulsion of  claim 1  by sonication. 
     
     
         17 . The method of  claim 16  wherein said sonication step further comprises sonicating said emulsion for a predetermined time and at a predetermined power. 
     
     
         18 . The method of  claim 17  wherein said sonication step further comprises sonicating said emulsion using a probe sonicator at a reduced power output. 
     
     
         19 . The method of  claim 16  further comprising the step of preparing said cellulose nanocrystals from microcrystalline cellulose or cellulose pulp derived from lignocellulosic biomass using sulfuric acid hydrolysis. 
     
     
         20 . A method of using a cellulose nanocrystal-based emulsion for reducing particle and vapor drift of an agrochemical, the method comprising the steps of incorporating said emulsion of  claim 1  into said agrochemical and applying said agrochemical to a crop. 
     
     
         21 . The method of  claim 20  further comprising the step of selectively tuning a droplet size distribution of said cellulose nanocrystal-based emulsion.