WO2011010910A1

WO2011010910A1 - A herbicide formulation

Info

Publication number: WO2011010910A1
Application number: PCT/MY2010/000130
Authority: WO
Inventors: Basri Mahiran; Chaw Jiang Lim; Omar Dzolkhifli; Bakar Salleh Abu; Basyaruddin Abd. Rahman Mohd.; Zaliha Raja Abdul Rahman Raja Noor
Original assignee: Universiti Putra Malaysia
Priority date: 2009-07-22
Filing date: 2010-07-20
Publication date: 2011-01-27
Also published as: MY146392A

Abstract

A herbicide concentrate in nano-emulsion form including an isotropic mixture comprising an aqueous phase in an amount of 20 to 55% w/w; glyphosate salts in an amount of 30 to 50% w/w; an oil phase of methyl ester mixture having carbon chain of C6 to C18 in an amount of 1.5 to 20% w/w; and a surfactant system consist of alkylpolyglucosides and an alkyl organosilicon by an amount of 15% w/w or less.

Description

A HERBICIDE FORMULATION

FIELD OF THE INVENTION

5The present invention relates to a herbicide formulation. In more specific, the disclosed herbicide formulation is prepared in nano-emulsion to ease the penetration of active ingredients into a targeted plant yet possessing good stability for long term release of the active ingredient to rid off the targeted plant. OBACKGROUND OF THE INVENTION

Glyphosate (N-phosphonomethylglycine), a herbicide active ingredient, is widely used to destroy weeds through inhibition of amino acid biosynthesis in shikimate pathway. To enhance efficiency of the glyphosate-based herbicide, adjuvants such as solvents, spreaders, dispersants, emulsifϊers, anti-foaming agents, wetting agents, anti-5freezing agents and surfactants are normally used in preparation of improved herbicide especially aiming to improve the composition in terms of solubility, compatibility, adsorption, penetration, translocation of the active ingredient into targeted plants, better rainfastness, and altered selectivity of the active ingredient toward different targeted plants. However, utilization of non-environmental friendly0adjuvants like xylene and agrochemical oil, tends to cause serious adverse effect to the surrounding environment and users. In order to minimize the adverse effects, glyphosate herbicide preparation has been intensively researched. Among all the options available, emulsion preparation shows promising results in delivering the active ingredient with minimized adverse effect. Yet, efficiency of the emulsion5preparation in delivering sufficient amount of active ingredient to the site of action still requires significant improvement. This is because glyphosate salts with highly ionic hydrophilicity is not able to penetrate through the hydrophobically cuticle and waxy layer of leaves. Therefore, various approaches have been employed to enhance penetration of glyphosate including increases lipophilicity and thermodynamic0activity of the active ingredient or increase stability of the preparation to extend the duration for delivery the active ingredients. For example, United States patent application no. 5543383 claims a herbicidal composition including isocyanate capped with high molecular weight diols, triols and polyols. The composition is a combination of surfactant, glyphosate, and a hydrated polymer or hydrophilic prepolymer consisting of isocyanate capped prepolymers 5which substantially comprises ethylene oxide, propylene oxide or butylene oxide.

Another United States patent application no. 5658853 provides glyphosate-containing aqueous herbicidal solution with improved rainfastness property. The disclosed lOcomposition comprises a herbicidally effective amount of glyphosate and/or glyphosate salt, acetylenic diol, and an alkyl polyglycoside surfactant for stabilizing the prepared solution.

Still United States patent no. 5668085 discloses aqueous concentrate containing

15glyphosate herbicide comprises solubilized glyphosate equivalent to at least 40 g/1 of glyphosate acid, a surfactant which is an amine or mixture of amine having from 8 to

22 carbon atoms, an agriculturally acceptable inorganic ammonium salt. The weight ratio of glyphosate herbicide expressed as glyphosate acid equivalent to amine surfactant(s) is from 1 :1.75 to 6:1 and the weight ratio of inorganic salt to glyphosate

20expressed as glyphosate acid equivalent is at 3.6:1.

Another United State patent no. 5789345 claims glyphosate liquid formulations containing amine types surfactants. Particularly, the stabilized glyphosate liquid formulation includes glyphosate or a salt and a surfactant, wherein urea is also present 25a minor amount sufficient to inhibit or prevent discoloration of the stabilized glyphosate liquid formulation.

Another United States patent no. 6127317 discloses a concentrated, aqueous herbicidal composition which comprises 0.1 to 7% w/v of an imidazolinyl acid salt,

3015 to 45% w/v of a glyphosate salt, 0.5 to 6% w/v of dimethyl sulfoxide, 0.5 to 15% w/v of a wetting agent, up to 10% w/v of an antifreezing agent, up to 1% w/v of an antifoaming agent, up to 3% w/v of a base, and water, provided that the composition has an initial pH of 6.0 to 7.0.

Further United State patent application no. 6451735 discloses a storage-stable high- 5strength aqueous glyphosate concentrate, preferably containing greater than 400 g/1 glyphosate expressed as acid, comprises the potassium salt of glyphosate, an alkylpolyglucoside (APG) and an alkoxylated alkylamine from about 160 to 300 g/1.

Further United State patent application no. 7223718 provides a single-phase lOherbicidal concentrate comprising an aqueous solution of glyphosate di-salt and at least one ammonium compound. The amount of glyphosate di-salt in the herbicidal concentrate is 10 - 50 % w/w, the amount for ammonium compound 16-52 % w/w and pH is 7.0 - 8.5.

15SUMMARY OF THE INVENTION

The present invention aims to provide a herbicide composition with good killing effect towards targeted plants via enhanced penetration of the active ingredient. The active ingredients contained in the disclosed composition can pass through the plant surface easily upon applying the composition to the targeted plants.

20

Another object of the present invention is to provide a herbicide composition possessing excellent stability and rainfastness ensuring continuous delivery of the active ingredient to the targeted plants to attain the killing efficiency in an extended duration.

25

Moreover, the present invention also discloses an eco-friendly herbicide composition by minimizing usage of toxic chemical compounds. Owing to its physiochemical properties, the disclosed composition is less likely to cause skin irritation on the user in contrast to conventional composition.

30

At least one of the preceding objects is met, in whole or in part, by the present invention, in which one of the embodiment of the present invention is a herbicide concentrate in nano-emulsion form including an isotropic mixture comprising an aqueous phase in an amount of 20 to 55% w/w; glyphosate salts in an amount of 30 to 50% w/w; an oil phase of methyl ester mixture having carbon chain of C6 to Cl 8 in an amount of 1.5 to 20% w/w; and a surfactant system consist of alkylpolyglucosides 5and an alkyl organosilicon by an amount of 15% w/w or less.

Further aspect of the disclosed invention which the glyphosate salts are any one or combination of glyphosate isopropylamine, glyphosate ammonium, glyphosate trimethylsulfonium, glyphosate trimesium, glyphosate sodium and glyphosate lOpotassium.

In another aspect, the alkylpolyglucosides and the alkyl organosilicon in the surfactant system is prepared in a ratio of 7 to 9: 1 to 3 by weight percentage while the alkylpolyglucosides has a carbon chain of C8 to C 16.

15

In further aspect, the alkyl organosilicon is methyl (propylhydroxide, ethoxylated) bis(trimethylsiloxy) silane.

Another major embodiment of the herbicide composition containing nano-emulsion of 0glyphosate salts acquired by gently mixing the herbicide concentrate of any of the preceding claims with water in a ratio of 1 to 1 : 100 to 500 by volume percentage.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 are phase diagrams with single surfactant in the system fatty acid

25 methyl esters (FAMEs)/nonionic surfactant/water in the presence of

41% w/w glyphosate isopropylamine (IPA) that the nonionic surfactants used were short alkyl polyglucosides (SAPGs), long alkyl polyglucosides L(APGs) and organosilicone, where L is isotropic and MP is multiphase;

30 Figure 2 are phase diagrams with mixed surfactant in the system

FAMEs/nonionic surfactant/water in the presence of 41% w/w glyphosate IPA that the mixed surfactant was SAPGs and organosilicone where L is isotropic and MP is multiphase.

Figure 3 are phase diagrams with mixed surfactant in the system

FAMEs/nonionic surfactants/water in the presence of 41% w/w glyphosate IPA that the mixed surfactants are LAPGs and organosilicone where L is isotropic and MP is multiphase; Figure 4 show electron micrographs of (a) organosilicone, (b) APGs, (c)

FAMEs and (d) glyphosate IPA;

Figure 5 show electron micrographs of (a) microemulsion concentrate without glyphosate IPA and (b) microemulsion concentrate with glyphosate

IPA;

Figure 6 show characteristic of glyphosate IPA microemulsion concentrates with using (a) SAPGs and (b) LAPGs.

Figure 7 show electron micrographs of (a) nano-emulsion and (b) glyphosate

IPA nano-emulsion formation by dilution of water;

Figure 8 are graphs showing the droplets size growth of nano-emulsions for (a) SAPGs and (b) LAPGs respected to Ostwald ripening and the droplets size growth for (c) glyphosate IPA nano-emulsions were measured for 24 hours; Figure 9 is the graph showing surface tension of glyphosate IPA nano- emulsions from Fl to F5 were compared to commercial RoundUp (RU) formulation and glyphosate IPA (GIPA) alone. DETAILED DESCRIPTION OF THE INVENTION

One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiment describes herein is not intended as limitations on the scope of the invention.

One of the embodiments of the present invention is a herbicide composition in nano- emulsion form including an isotropic mixture comprising an aqueous phase in an amount of 20 to 55% w/w; glyphosate salts in an amount of 30 to 50% w/w; an oil phase of methyl ester mixture having carbon chain of C6 to Cl 8 in an amount of 1.5to 20% w/w; and a surfactant system consist of alkylpolyglucosides and an alkyl organosilicon by an amount of 15% w/w or less. It is important to be noted that the present invention, through appropriate proportionate the above stated components, prepared nano-scale emulsion is capable of penetrating surface of the targeted plants such as weed easily. It is known the cuticle and waxy layer surface of the targetedplant is highly hydrophobic and not permeable to the hydrophilic glyphosate compounds. However, it was found by the inventors of the present invention that the penetration of the glyphosate compounds are greatly enhanced by preparing the glyphosate compounds in nano-emulsion form. Glyphosate compound in nano-size can pass through void available on the waxy surface and initiate the amino acidinhibition once entering into the targeted plants. Moreover, utilization of the surfactant system increase lipohilicity of the glyphosate compounds. In more specific, the glyphosate compounds and the surfactants form an emulsion which the hydrophilic glyphosate compounds are enclosed within a lipohilic outer layer thus increasing permeability of the glyphosate compounds through the plant surface. In themost preferred embodiment, the disclosed composition appears as optical transparent solution indicating stable nano emulsion. In more preferred embodiment, the aqueous phase employed in the present invention is, but not limited to, distilled water because distilled water offer greater purity to the prepared composition. Though an amount of 20 to 55% w/w aqueous phase in used in 5the preferred embodiment, the more preferred embodiment employs 30 to 50% w/w of aqueous phase and 40 to 45% w/w in the most preferred embodiment.

In respect to the preferred embodiment, surfactant is employed to improve formation of the emulsion. The surfactant utilized is preferably biocompatible to reduce the lOlikelihood to cause skin irritation or any other complication to the subject. The biocompatible surfactant of the present invention is, but not limited to, alkyl polyglucosides. Alkyl polyglycoside renders good bio-degradability to the present invention after application. Hence, the present invention brings less adverse effect to the applied environment. In the more preferred embodiment, a co-emulsifier may be

15used besides the primary emulsifier. Preferably, the co-emulsifier is an organosilicon, more preferred alkyl organosilicon. Representative example of the organosilicon is methyl (propylhydroxide, ethoxylated) bis(trimethylsiloxy) silane. Particularly, the surfactant system in the most preferred embodiment consists of two different types of surfactants. A primary surfactant, alkyl polyglucosides, and coupled with a co-

20surfactant, alkyl organosilicon. Organosilicon is selected as one of the components in preparing the disclosed composition owns to its superb wetting property which assists spreading of the disclosed composition droplet upon application and consequently increase the efficiency. In accordance with the preferred embodiment, the amount of emulsifier and/or co-emulsifier is less than 15% w/w of the total concentrate

25composition relying upon the types of emulsifier used. Through the combination of these two different types of surfactants in the present invention, the emulsion formed is in nano scale and shows good stability for a long period. The good stability offers longer shelf life for the present invention. Alkyl polyglucosides in the present invention is known of its good biodegradability upon application leaving less toxic

30residues in the applied environment. The preferable amount of the alkyl polyglucosides to be used in the present invention is around 2 to 12.5% w/w. To attain the objects of the present invention, the alkyl polyglucosides and the alkyl organosilicon in the surfactant system is prepared in a ratio of 7 to 9: 1 to 3 by weight percentage. In order to achieve better bio-compatibility and reduce the likelihood of causing skin irritation to the user, the amount of organosilicon employed in the present invention is preferably not more than 3.5% by weight or in between 0.1 to

53.5% w/w.

Pursuant to the preferred embodiment, the alkylpolygluco sides has a carbon chain of C8 to Cl 6. The emulsion droplet prepared from the alkylpolyglucosides with carbon chain C8 to ClO has droplet size distributed in the range as small as below 10 nm in lOopposed to those having carbon chain C12 to Cl 6 producing emulsion with droplet size only less than lOOnm. As setting forth, penetration of the active ingredient into the plants is much significant in emulsion with smaller droplet size. Consequently, in the preferred embodiment, alkylpolyglucosides with C8 to ClO carbon chain is employed.

15

Another preferred embodiment, a mixture of methyl ester with various carbon chain is used as oil phase to increase the lipophilic activity of glyphosate salt. Besides, utilization of methyl ester mixture was found capable of reducing viscosity of the prepared herbicide concentrate and rendering higher flowability of the herbicide 0concetrate. Thus, it increases mobility and better spreading of emulsion droplets in the herbicide concentrate. Moreover, methyl ester with shorter carbon chain such as those with carbon chain Ce to Ci o is preferably selected for in the more preferred embodiment to give lower rigidity and lower viscosity to the prepared concentrate. The amount of methyl ester can range from 1.5 to 20% w/w.

5

For acquiring better killing effect, the preferred embodiment uses glyphosate isopropylamine as the active ingredient to eradicate the targeted plants. Nonetheless, the glyphosate salts in the present invention can be any one or combination of glyphosate isopropylamine, glyphosate ammonium, glyphosate trimethylsulfonium,

30glyphosate trimesium, glyphosate sodium and glyphosate potassium. Accordingly, another major embodiment of the present invention involves a herbicide composition derives from dilution of the above mentioned herbicide concentrate using distilled water. The herbicide composition can be obtained through gently stirring the herbicide concentrate with distill water in an appropriate proportion. In more specific, 5the herbicide composition containing nano-emulsion of glyphosate salts is acquired by gently mixing the above mentioned herbicide concentrate of with water in a ratio of 1 to 2 : 100 to 500 by volume percentage. Dilution of the herbicide concentrate generates nano-emulsion components that are kinetically stable throughout the time of application within day. The generated nano-emulsion is optically transparent and lOtranslucent. The amount of glyphosate salt to be used this embodiment to attain nano- emulsion is preferably range between 0.01 to 1% w/w. The disclosed composition is not overloaded with active ingredient to promote penetration of the active ingredient as long the glyphosate nano emulsion is maintained within the preferred size.

15The following example is intended to further illustrate the invention, without any intent for the invention to be limited to the specific embodiments described therein.

Example 1

An aqueous glyphosate IPA (62% w/w active ingredient) was supplied by Crop 0Protection Sdn. Bhd. (Malaysia). APGs surfactants, octyl/decyl polyglucosides (45:55) and dodecyl/tetradecyl/hexadecyl polyglucosides (68:26:6) and FAMEs of methyl caprylate/caprate (54:46) were gifts from Cognis Sdn. Bhd. (Malaysia). Organo silicone surfactant [methyl (ethoxylated propylhydroxide) bis(trimethylsiloxy) silane] was provided from Dow Corning Pte. Ltd. (Singapore). Deionized water was

25prepared from our laboratory.

Pseudoternary phase diagrams were constructed. Mixtures of FAMEs with nonionic surfactant were prepared in 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9 and 0:10 into different ampoules. Increment 5% w/w of water was titrated into the ampoules. The 30percentage of glyphosate IPA was calculated as 41% w/w as final total weight and added gradually after every increment of water. All components were weighed, sealed, homogenized and centrifuged using Hermle Model Ettek (Germany) at 5000 rpm for 15 minutes at room temperature 25⁰C. The resulting mixtures were visualized through two crossed polarizing plates for identification of physical phase appearance. Further phase diagrams were constructed by using mixed surfactant of APGs with different alkyl chain length and organosilicone. The isotropic regions were selected 5for further stability and characterization tests.

Figure 1 shows the phase behaviour of FAMEs/surfactant/water in the presence of 41% w/w glyphosate IPA whereby short APGs (SAPGs) (Figure l(a)), long APGs (LAPGs) (Figure l(b)) and organosilicone (Figure l(c)) surfactants were used. OIsotropic region (L) and multiphase region (MP) were observed in the phase diagrams with APGs surfactants. LAPGs gave larger isotropic region by emulsifying higher concentration of FAMEs. The longer alkyl chain LAPGs provides higher hydrophobic surface to be attracted with FAMEs. However, organosilicone surfactant [methyl (ethoxylated propylhydroxide) bis(trimethylsiloxy) silane] shows no isotropic region 5throughout the phase diagram.

The use of combination APGs and organosilicone surfactants, the isotropic region was found larger compared to the single surfactant APGs. Figure 2 shows the use of SAPGs with organosilicone surfactant. With the mixed surfactant, isotropic region0was found in the ratio SAPGs:organosilicone at 9:1, 8:2, 7:3 and 6:4 respectively and the largest isotropic region was at 7:3. Figure 3 shows the use of LAPGs with organosilicone, isotropic region was found at mixed surfactant ratios 9:1, 8:2 and 7:3 respectively and the largest isotropic region was at 9:1. Organosilicone surfactant was found to co-emulsify FAMEs in the mixed surfactant system. In using LAPGs, less5organosilicone was used to co-emulsify the maximum of FAMEs but with SAPGs, more organosilicone surfactant was used. Organosilicone was acted as "more hydrophobic chain" to help SAPGs to co-emulsify the maximum of FAMEs.

Mixed surfactant has provided better hydrophilic-lipophilic balance (HLB), leads to0enhancement in flexibility of surfactant layer and ability to partition at high levels into the oil-water interface (Warisnoicharoen et al. , 2000) therefore greatly increase the oil content. The presence of organosilicone surfactant (HLB=I 1.5) helps to lower the HLB of SAPGs and LAPGs (HLB=I 3.6 and 12.1) in the emulsion system, thus maximize the incorporation of FAMEs. The optimized mixed HLB value can be calculated by the following Equation 1 (Liu et al, 2006):

HLB _mix = x% HLB, + y%HLB₂ (1)

5

where x% and y% is the mass percentage of surfactant in mixed surfactant respectively.

In addition, small droplets size and stable isotropic emulsions were formed with lOmixed surfactant in which the addition of surfactant causes interfacial film to condense and to be stable while addition of co-surfactant causes the film to expand (Kale and Allen, 1989).

Since glyphosate IPA salt is highly hydrophilicity (ionic) than water (polar), and

15insoluble in most organics (octanol/water log P = -1.70) (Wester et al, 1991) therefore glyphosate IPA has negligible effect on the adsorption to FAMEs. From the phase diagrams, the isotropic emulsion appeared from high concentration of water region. Higher water concentration provides higher stability on thermodynamic equilibrium. Water content increases the energy of intermolecular interaction and the 0H-bond network perfection (Kartsev et al, 2009). As a result, stable spatial network of H-bond between water and mixed surfactant was formed.

Example 2

Nanophox SympaTec GmbH, Clausthal-Zellerfeld (Germany), with Photon Cross

25Correlation Spectrometer (PCCS) using laser light scattering was employed to measure droplets size and distribution of concentrate-generated emulsions (approximately 200-fold dilution of concentrate with deionized water) at a temperature of 25 ⁰C. The samples were loaded onto 1 cm² cuvettes in a thermostated chamber. A standard evaluation of 2^nd cumulant algorithm evaluation mode was used

3 Oto calculate the droplets size distribution. In all measurements, the value of X90 was used as a representation of the droplet size and distribution. Droplet size of samples was analyzed randomly from the isotropic regions. The selection of samples was based on a maximum 16% w/w of mixed surfactant. Figure 2(a) to 2(c) show the labeled droplets size using SAPGs with mixed surfactant ratio (SAPGs:organosilicone) 9:1 to 7:3. Figure 2(a) shows the ratio of mixed surfactant 59:1; droplets size depicted 36.99nm, 54.70nm and 80.70nm at water concentration 55%, 75% and 95% respectively. The increasing of water composition may result in changes of the droplet size distribution associated with break-up/coagulation or coalescence (Dowding et al, 2001). The lower water concentration, the higher concentration of surfactant and the smaller the droplets size as the surfactant could lOcontrol the total interfacial area and hence the average droplets size (Solans et al, 2005). Figure 2(b) shows the ratio of mixed surfactant 8:2; compared to mixed surfactant ratio of 9:1, the droplets size increased to 53.73nm, 92.38nm and 130.40nm which corresponded to the increasing concentration of organosilicone (decreasing of APGs). But, towards FAMEs rich region, isotropic region appeared, with smaller

15droplets size 16.1 lnm at water concentration 65%. This observation could be caused by the presence of more organosilicone which could co-emulsify higher concentration of FAMEs. Figure 2(c) shows the ratio of mixed surfactants 7:3; the droplets size continuously increased to 66.46nm, 129.53nm and 186.30nm which corresponded to water concentrations of 55%, 75% and 95% respectively. However, towards the 0FAMEs region, the isotropic appeared at the droplets size 24.09nm, 69.28nm and 80.69nm corresponding to 55%, 75%, and 95% water concentration respectively. At mixed surfactant ratio at 6:4, near all the isotropic regions disappeared. The instability was influenced by the excess organosilicone, where the HLB value exceeds (lower than) the optimized HLB value, therefore reduced the flexibility of surfactant

25system. Overall, the droplets size closest to the water-mixed surfactant apex became larger whereas the droplets size became smaller towards higher concentration of FAMEs region by increasing the organosilicone surfactant concentration until the mixed surfactant ratio at 7:3.

30Figure 3 (a) to 3(b) show the labeled droplets size using LAPGs with mixed surfactant ratio (LAPGs:organosilicone) 9:1 to 8:2. Figure 3(a) shows the ratio of mixed surfactant 9:1; the droplets sizes were 87.14nm, 87.54nm and 106.67nm at 55%, 75% and 95% concentration of water. Towards FAMEs rich region, the droplets sizes were found at 92.12nm, 149.14nm and 170.22nm at water concentration of 45%, 65% and 85%. Closer to the FAMEs rich regions, the droplet sizes were 84.56nm, 95.14nm and 183.48nm at water concentration of 55%, 75%, and 95% respectively. Closer and 5closer, the droplets sizes became smaller at 40.89nm, 44.56nm and 82.79nm. Figure 3(b) shows the ratio of mixed surfactant 8:2; the droplets sizes were 191.85nm, 128.10nm and 87.94nm. Towards FAMEs rich region, the droplets sizes were found smaller at 88.98nm, 54.48nm and 57.19nm. From the trends of droplets size, the direction of isotropic appearance in phase diagrams can be predicted when the Odevelopment on mixed surfactant ratio. The droplets with reducing size demonstrated the direction of isotropic regions move towards. Conversely, the increasing size indicated towards the appearance of multiphase region. Smaller droplet size is more stable such in microemulsion and nano-emulsion compared to macroemulsion (Jafari et al, 2008). As a result, droplet size can be used as an indicator to optimize the5selection of isotropic region. Overall, the alkyl chain length of APGs affected droplets size. LAPGs gave higher average droplets size compared to SAPGs.

Example 3

A few potential composition of concentrated isotropic emulsion with loaded0glyphosate IPA were selected from the phase diagrams. Emulsion concentrates without glyphosate IPA were prepared at same ratio in the system of FAMEs/mixed surfactants/water which were identical to the selected composition. This purpose is to investigate the effect of glyphosate IPA on the emulsion concentrates. Both sample stability on the emulsion concentrates with and without glyphosate IPA were5compared.

The samples of concentrated emulsion were stored in room temperature 25 ⁰C and 45 0C respectively for three months. Further stability investigation on thaw cycle was tested. All samples were prepared into thin- walled glass tube (internal 10 mm, height0= 95 mm), which were cooled by placing them in a 5 ⁰C freezer for 24 hours and then thawed by placing them in 25 ⁰C for 24 hours. The thaw cycle was repeated three times. The changes on physical stability of the samples were recorded. Five samples were selected with the percentage of compositions as summarized in Table 1. These samples were called glyphosate IPA microemulsion concentrate and labeled as Fl, F2, F3, F4 and F5. To compare the effect of glyphosate IPA on 5emulsion system, microemulsion concentrates labeled El, E2, E3, E4 and E5 were prepared in the system of FAMEs/APGs:organosilicone/water (Table 2) whereby the ratios were identical to the emulsion system of Fl, F2, F3, F4 and F5. All samples were found to be stable at 25°C except E3 was found unstable to form two phases. Glyphosate IPA stabilized the microemulsion concentrate by incorporating two lOcolourless phases into single isotropic phase. Commonly, the investigation of phase behaviour by constructing ternary phase diagram oil/surfantant(s)/water system and further select isotropic regions for adding active ingredient is not optimized. Therefore, the construction of phase diagrams with adding the concentrated glyphosate IPA as a new tool to optimize the stable region for formulation.

15

Table 1 : Composition of glyphosate IPA microemulsion concentrates with the described percentage (w/w) for each component of materials

20

Table 2: Composition of microemulsion concentrates without glyphosate IPA with the described ercenta e w/w for each com onent of materials

* Not stable at 25 ⁰C At 45⁰C, samples labeled E5 and F5 were found unstable. Microemulsion is thermodynamically stable, but increasing the storage temperature of the microemulsion concentrates resulted in a decrease in the stability on thermodynamic 5equilibrium. This result is expected as intermolecular bonds are weakened as the temperature increases (Kartsev et al. 2009) Centrifugation only removes the sedimentation and creaming of microemulsion system physically but not chemically. E5 and F5 contain higher FAMEs compared to El, E2, E4 and Fl, F2, F3, F4 respectively. The excess FAMEs form van der Waals forces on the interface of mixed lOsurfactants. Therefore, high temperature has weakened the forces of oil droplets from the hydrophobic core of the surfactants.

In the thaw cycle test, samples E4, F4 and E5, F5 with LAPGs were found to precipitate at 5⁰C but showed no phase separation. Samples El, E2 and Fl, F2, F3

15 with SAPGs were found to be stable. The viscosity of LAPGs was 21 ,500 cPs while SAPGs was 4,800 cPs. Alkyl chain length influences the viscosity of microemulsion concentrate system. Temperature was found to affect the viscosity behaviour of APGs surfactant. The viscosity of surfactant increases as the decrease temperature. Therefore, LAPGs with higher viscosity can form precipitate easily.

20

Example 4

High resolution of transmission electron microscopy (TEM) (Hitachi H-7100, Japan) was employed to characterize the micro/nanostructure of the samples. Negative staining method was used where the samples were prepared by dropping two droplets

25on copper grid supported Formvar films. The samples were stained with uranyl acetate solution (2% uranyl acetate in water). The excess uranyl acetate on the samples was gently wiped off using filter paper and dried in open air at room temperature overnight.

30Figure 4 shows the microstructure of organosilicone, APGs, FAMEs and glyphosate IPA respectively. Figure 4(a) shows the self-assembly of organosilicone which form aggregation of spherical micelles. Figure 4(b) shows the self-assembly of APGs which aggregation in rod-like shape micelles. Figure 4(c) shows FAMEs droplets appeared as small black spot. Figure 4(d) illustrates the glyphosate IPA with sharp needled crystals which formed the network system.

5The combination of FAMEs, mixed surfactant APGs and organosilicone, and water formed microemulsion concentrate and was illustrated in Figure 5. Samples El, E2, E4, and E5 showed the similar result in TEM micrographs as shown in Figure 5(a). The mixed surfactant micelles formed irregular shape. Mixed micelles were found to influent the aggregated structures on micellar system (Israelachvili, 1992). The lOpresence of co-surfactant organosilicone may alter the shape of micelles (Narayanan et ah, 2008), improved the hydrophobicity of emulsion system, as a result, increased the adsorption of FAMEs on the hydrophobic part of mixed surfactant.

In the presence of glyphosate IPA, samples Fl, F2, F3, F4 and F5 shows the similar 15image in TEM micrographs Figure 5(b). The microemulsion systems formed crosslinked network structure. The microemulsion concentrate of sample E3 was unstable. However, the presence of glyphosate IPA stabilized the systems via ionic charge interaction. Glyphosate IPA, a salt, is positively and negatively charged and strongly attracted to each others. The nonionic surfactants hydrophilic part of 0organosilicone and APGs possess the polar charges, attract to the end of glyphosate ionic charges and stabilized the microemulsion system. The formation of network structure contributed to the longer aging stability of microemulsion system which the droplets size growth was very slow at near constant within three months.

25

Example 5

Modular Compact Rheometer (MCR) 300 (Paar Physica GmbH, Austria- Europe) with cone and plate geometry (diameter 17 mm with the cone angle 1°) was used to study the rheological behaviour of the samples. The flow curve and the viscosity of the

30samples were determined by rotation tests controlled shear rate. The shear rate was changed from 0 to 500 s^"1 and decreasing from 500 to 0 s^'1. The flow behaviour of samples was determined by plotting the rheological graphs. Viscosity as an aspect in rheology is defined as deformation and flow characteristic of fluids behaviour. The rheology behaviour of glyphosate IPA microemulsion concentrate can be determined by flow curve of shear stress (Pa) versus shear rate(l/s). Figure 6 illustrates the effect of alkyl chain length on viscosity and flow behaviour of concentrated fluid samples. Figure 6(a) shows with using SAPGs, linear curves were obtained and resulted shear stress is directly proportional to shear rate. From the Newton's law (Equation 2) of viscosity, T = -μ (dv/dy) (2) where μ is shear viscosity (Pa.s), dv/dy is shear rate (1/s) and F is shear stress (Pa). The gradient of the curve is described as shear viscosity. Constant shear viscosity was found and independent on shear rate between 0 to 500s^"1. Consequently, short alkyl chain APGs behaves as Newtonian fluids with extremely low viscosity. The constant values of shear viscosity for samples Fl, F2 and F3 were 0.08 Pas, 0.09 Pas and 0.05 Pas respectively. Compared to Fl and F2, the shear viscosity of F3 is lower due to the higher water concentration gives the lower viscosity. From Figure 6(b), the using of LAPGs, shear rate dependent on viscosity and behaves as non-Newtonian. The viscosity was found to decrease when the shear stress was increasing and resulted shear thinning. This situation is caused by the perturbation and breakdown of the three dimensional droplet structure formed in the emulsion and leads to formation ordered layer structured (Raghavan and Khan, 1997). Sample F5shows the lower shear viscosity compared to F4. The perturbation of droplet structure of sample F5 caused by shear is instantly recovered by the Brownian forces and the droplet structure remains effectively constant (Saiki et al, 2008). Shear thinning causes the sample behaves pseudoplastic flow (Szelag and Paudzer, 2003). As a result, by increasing the alkyl chain length, the shear thinning is increasing andbehaves as non-Newtonian fluids. Compared to Newtonian, the shear thinning of non- Newtonian contributes to the inefficiency in pesticides application after long period storage which will form higher viscosity. Example 6

Nano-emulsions were prepared by using low energy emulsification method by mixing all appropriate components to generate isotropic concentrates. The concentrates were 5injected into very much larger volume of water (ratio of 1 into 200) under gentle stirring to produce the nano-emulsions. The measurement of droplet size growth for nano-emulsion samples was carried out on the 0, 2, 4, 6, 12, and 24 hour.

Nano-emulsion is "dispersed", a non-equilibrium system which is differentiated from lOmicroemulsion which is interpreted as "solubilized" (Gutierrez et al, 2008). The dilution of OAV microemulsion concentrate with large volume of water causes dispersion and generates the formation of nano-emulsion. TEM micrographs of Figure

7(a) and 7(b) show the after aqueous dilution of microemulsion concentrate and glyphosate IPA microemulsion concentrate. The dilution with water causes the

15aggregated micellar system to breakdown into separate micelles. Before dilution, the aggregated micelles are surrounded by film. Water as dispersed medium supply kinetic energy which disrupts the interfacial films of micellar systems, and contributed to the smaller droplets size. Therefore, the degree of dilution causes the completely disruption of interfacial film of the micelles aggregates and forms

20individual micelles, disperse uniformly, and leads to better spreading.

Figure 7(b) shows that in the presence of glyphosate IPA, the dispersion with water leads to nano-structured emulsion which the nano-emulsion droplets were attracted to the needle shaped of glyphosate crystals. The attraction to the glyphosate IPA are 25either in the group (darker colour) or individually remains dispersed in the medium. The attachment of nano-emulsion droplets on the glyphosate IPA crystal improves the delivery system into the target organisms as nano-emulsion droplets possess larger surface area, improves the pesticides bioeffϊcacy.

30Droplets size growth of nano-emulsion with/without glyphosate IPA was measured as a function of time. The aging of nano-emulsion could be due to two processes; coalescence and Ostwald ripening. Figure 8(a) with SAPGs and 8(b) with LAPGs show the nano-emulsions respected the Ostwald ripening behaviour where the cube of radius, r³ is proportional to the time regardless of the length of APGs alkyl chain used. From the Lifshitz-Slezov and Wagner (LSW) theory equation, the Ostwald ripening rate (Equation 3) is:

5

ω = d^/ dt = (8/9)[(C∞γVmD) / pRT (3) where C∞ is the bulk phase solubility (the solubility of the oil in an infinitely larger droplet), γ is the interfacial tension, Vm is the molar volume of the oil, D is the lOdiffusion coefficient of the oil in the continuous phase, p is the density of the oil, R is the gas constant, and T is the absolute temperature.

Ostwald ripening in an OAV nano-emulsion depends on the aqueous solubility of oil (Taylor, 2003). It was suggested that the excess micelles formed in the aqueous phase

15which act as solubilization parts for the added oil. However, the oil solubilized was not dispersed in the continuous phase and lowers the solubility of oil in the bulk phase, therefore contributes to the Ostwald ripening. Sample E5 was found to have higher Ostwald ripening rate, because with the highest concentration (14.36%w/w) of FAMEs among the other samples. The higher solubility of FAMEs causes the higher 0Ostwald ripening rate growth. Figure 8(c) shows the droplets size growth of glyphosate IPA incorporated nano-emulsion. The samples Fl, F2, F4 and F5 exhibited constant in droplets size growth but sample F2 showed large increase after dilution with water. As a result, the application of herbicide with the sample Fl, F4 and F5 provides better efficiency which maintain in nano-size droplets in 24 hours.

25

Example 7

Surface tension of nano-emulsion samples was measured on a Kruss K6 tensiometer (Kruss, Germany) by using the de Nouy ring method. Measurements were calibrated 30using deionized water with a surface tension of 72-73 mN/m. before measurement of the samples. Correction for the ring geometry and the hydrostatic lifted volume of liquid was made using the method of Harkins and Jordan or Zuiderma and Waters (Milkereit and Garamus, 2005). The reproducibility between measurements on different samples was +1 mN/m.

Figure 9 depicts the dilution of glyphosate IPA (1 to 200) produced surface tension 562.8 mN/m. The high surface tension may lead to inefficacy droplet deposition with higher contact angle, thus, droplets do not spread well. The presence of mixed surfactant, the surface tension was reduced by nearly one-third. The surface tension shows 25.4, 25.0, 24.4, 26.8 and 26.5 mN/m corresponded to the samples Fl, F2, F3, F4 and F5 respectively. The presence of mixed surfactant was found to reduce surface lOtension of glyphosate IPA aqueous solution effectively which increases the surface area and decrease in the interfacial tension (Izquierdo et al, 2002). Compared to commercial Round Up glyphosate IPA which using polyoxyethylene amine (POEA) surfactant, the dilution in same rates gave surface tension of 47.8 mN/m.

15However, hydrophobic chain plays the role in surface tension of liquids. The alkyl chain length of APGs surfactant affected the surface tension. LAPGs resulted in average slightly higher surface tension than SAPGs. Longer hydrophobic alkyl chain contributed to the higher surface tension. In fact, the mobility of longer alkyl chain is lower comparing to shorter alkyl chain. The SAPGs with smaller droplet size tend to 0increase the surface area and lower the surface tension. In addition, the increasing of viscosity of LAPGs increases the surface tension.

It is to be understood that the present invention may be embodied in other specific forms and is not limited to the sole embodiment described above. However 5modification and equivalents of the disclosed concepts such as those which readily occur to one skilled in the art are intended to be included within the scope of the claims which are appended thereto. References

Cramp, G.L., Docking, A.M., Ghosh, S. and Coupland J.N., (2004). On the stability of oil-in- water emulsions to freezing. Food hydrocolloids, 18 : 899-905.

5Dowding, P. J., Goodwin, J. W. and Vincent, B., (2001). Factors governing emulsion droplet and solid particle size measurements performed using the focused beam reflectance technique. Colloids and Surface A, 192: 5-13.

Forgiarini, A., Esquena, J., Gonzalez, C. and Solans, C, (2001). Formation of nano- lOemulsions by low-energy emulsion methods at constant temperature. Langmuir, 17:

2076-2083.

Foy, C.L., (1993). Progress and development in adjuvants use since 1989 in the USA. Pesticides Science, 38: 65-76.

15

Foy, C.L., (1996). Adjuvants - current technology and trends. In: Foy, C. L., Pritchard, D. W. (Eds.), Pesticide Formulation and Adjuvant Technology. CRC Press, Boca Raton, FL, pp. 323-352.

20Gutierrez, J.M., Gonzalez. C, Maestro, A., Sole, L, Pey, CM. and Nolla, J., (2008). Nano-emulsions: New applications and optimization of their preparation. Current Opinion in Colloid and Interface Science, 13: 245-251.

Israelachvili, J. N., (1992). Intermolecular and surface forces. 2nd ed. London, 25Academic Press.

Izquierdo, P., Esquena, J., Tadros, Th. F., Dederen, C, Garcia, M. J., Azemar, N, Solans, C, (2002). Formation and stability of nano-emulsions prepared using phase inversion. Langmuir, 18: 26-30.

30

Jafari, S.M., Assadpoor, E., He., Y. and Bhandari, B., (2008). Re-coalescence of emulsion droplets during high-energy emulsification. Food Hydrocolloids, 22: 1191- 1202.

35KaIe, N.J. and Allen, L.V., (1989). Studies on microemulsion using Brij 96 as surfactant and glycerin, ethylene glycol and propylene glycol as cosurfactants. International Journal of Pharmaceutics, 57: 87-93.

Kartsev, V.N., Shtykov, S.N., Bogomolova, LV. and Ryzhov, I.P., (2009). 40Thermodynamic stability of microemulsion based on sodium dodecyl sulfate. Journal of Molecular Liquid, 145: 173-176.

Liu, W., Sun, D., Li, C, Liu, Q. and Xu, J., (2006). Formation and stability of paraffin oil-in- water nanoemulsions prepared by the emulsion inversion point method. Journal A5of Colloid and Interface Science, 303: 557-563. Milkereit, G. and Garamus, M., (2005). Complex effect of ethyl branching on the supramolecular structure of a long chain neoglycolipid. Colloids and Surface A: Physicochemical Engineering Aspects, 268: 155-161.

5Mulqueen, P., (2003). Recent advances in agrochemical formulation. Advances in Colloid and Interface Science, 106: 83-107.

Narayanan, S.S., Sinha, S.S., Sarkar, R. and Pal, S.K., (2008). Picosecond to nanosecond reorganization of water in AOT/lecithin mixed reverse micelles of lOdifferent morphology. Chemical physics letters, 452: 99-104.

Pakpayat, N., Nielloud, F, Fortune, R., Tourne-Peteilh, C, Villareal, A., Grillo, I. and Bataille, B., (2009). Formulation of ascorbic acid microemulsions with alkyl polyglucosides. European Journal of Pharmaceutics and Biopharmaceutics, 72(2): 15444-452.

Porras, M., Solans, C, Gonzalez, C. and Gutierrez, J.M., (2008). Properties of water- in-oil (W/O) nano-emulsions prepared by a low-energy emulsifϊcation method. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 324: 181-188. 20

Raghavan, S.R. and Khan, S.A., (1997). Shear-thickening response of fumed silica suspensions under steady and oscillatory shear. Journal of Colloid and Interface Science, 185:57.

25Rodham, D.K., (2000). Colloid and interface science in formulation research for crop protection products. Current opinion in colloid and interface science, 5: 280-287.

Saiki Y., Horn, R.G. and Prestidge, C.A., (2008). Rheological transition of concentrated emulsions during successive shearing cycles. Journal of Colloid and

Science, 3>21: 440-445.

Szelag, H. and Paudzer, B., (2003). Rheological properties of emulsions stabilized by acylglycerol emulsifiers modified with sodium carboxylates. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 219: 87-95.

35

Solans, C, Izquierdo, P., Nolla, J., Azemar, N. and Garcia-Celma M.J., (2005). Nano- emulsions. Current Opinion in Colloid Interface Science, 10: 102-110.

Somasundaran, P., Mehta, S. C. and Purohih, P., (2006). Silicone emulsions. Advances 40m Colloid and Interface Science, 128-130: 103-109

Tadros, ThF., (1999). In: E.D. Goddard, J.V. Gruber (Eds.). Principles of Polymer Science and Technology Cosmetics and Personal Care, Dekker, New York.

45Tadros, ThF. (2004). Application of rheology for assessment and prediction of long- term physical stability of emulsions. Advances in Colloid and Interface Science, 108- 109: 227-258. Tamilvanan, S., Khoury, K., Gilhar, D. and Benita, S., (2001). Ocular delivery of cyclosporin A. I. Design and characterization of cyclosporin A-loaded positively- charged submicron emulsion. S.T.P. Pharma Science, 11: 421-426.

5

Taylor, P. (2003). Ostwald ripening in emulsions: estimation of solution thermodynamics of the disperse phase. Advances in Colloid and Interface Science, 106: 261-285.

lOWang, L., Li, X., Zhang, G., Dong, J. and Eastoe, J., (2007). Oil-in-water nanoemulsions for pesticide formulations. Journal of Colloid Interface Science, 314: 230-235.

Warisnoicharoen, W., Lansley, A.B. and Lawrence, M.J., (2000). Nonionic oil-in- 15 water microemulsions: the effect of oil type on phase behaviour. International Journal of Pharmaceutics, 198: 7-27.

Wester, R.C., Melendres, J., Sarason, R., McMaster, J. and Maibach, H.I., (1991). Glyphosate skin binding, absorption, residual tissue distribution, and skin 20decontamination. Fundamental Applied Toxicology, 16: 725-732.

Claims

CLAIMS:

1. A herbicide concentrate in nano-emulsion form including an isotropic mixture comprising

an aqueous phase in an amount of 20 to 55% w/w;

glyphosate salts in an amount of 30 to 50% w/w;

an oil phase of methyl ester mixture having carbon chain of C6 to Cl 8 in an amount of 1.5 to 20% w/w; and

a surfactant system consist of alkylpolyglucosides and an alkyl organosilicon by an amount of 15% w/w or less.

2. A herbicide concentrate according to claim 1, wherein the aqueous phase is distilled water.

3. A herbicide concentrate according to claim 1, wherein the glyphosate salts are any one or combination of glyphosate isopropylamine, glyphosate ammonium, glyphosate trimethylsulfonium, glyphosate trimesium, glyphosate sodium and glyphosate potassium.

4. A herbicide concentrate according to claim 1, wherein the alkylpolyglucosides and the alkyl organosilicon in the surfactant system is prepared in a ratio of 7 to 9: 1 to 3 by weight percentage.

5. A herbicide concentrate according to claim 1, wherein the alkylpolyglucosides has a carbon chain of C8 to C 16.

6. A herbicide concentrate according to claim 1, wherein the alkyl organosilicon is methyl (propylhydroxide, ethoxylated) bis(trimethylsiloxy) silane.

7. A herbicide composition containing nano-emulsion of glyphosate salts acquired by gently mixing the herbicide concentrate of any of the preceding claims with water in a ratio of 1 to 2 : 100 to 500 by volume percentage.