Use Thereof

Field of the invention

The present invention relates to a type of formulations comprising a terpolymer and an active substance, preparation thereof, and the use thereof in the preparation of ready-for-use formulations.

Background of the invention

Many types of active substances are ideally used as aqueous formulations (mainly as aqueous solutions or aqueous dispersions) in various fields. For example, in the field of plant protection, active substances such as insecticides, acaricides, nematicides, fungicides and herbicides as well as growth regulators are frequently formulated and sold as concentrates, such as aqueous concentrates or as concentrates in organic solvent, for example suspensions or emulsions, and also as solid concentrates, such as powders, dusts or granules. These formulations, before their application, are generally diluted to the desired application concentration by addition of a large amount of water. Also, pharmaceutically and cosmetically active substances and food additives, as well as active substances used in biological field, such as vitamins, provitamins, proteins, RNA and DNA and the like, are also generally formulated into formulations in aqueous medium for transportation and/or usage. Thus, it is necessary for the active substances to be effectively stable or dissolved in aqueous.

However, the main problems are that, many active substances have low solubility, i.e., generally less than 10 g/1 at 23°C/1 atm. (1013 mbar). When these active substances are formulated into aqueous formulations or aqueous ready-for-use formulations, they form unstable heterogeneous systems in which the active substance is present as emulsified or dispersed phase in a continuous aqueous phase. The active substances tend to separate out of the system, for example by crystallization or creaming or sedimentation. This reduces the availability of the active substance, resulting in low utilization of the active substance. Moreover, for purpose of proper metering of the active substance, it is also desirable to have a stable system in which the active substance is homogeneously distributed.

To solve these problems, conventional methods, such as lyophilization, utilization of various surfactant and/or emulsifier and/or dispersant, have been generally used to stably distribute the active substance in aqueous formulation or aqueous ready-for-use formulations, in order to obtain a stable system and to avoid formation of large aggregate or droplet of active substance, and to enhance the utilization of the active substance. However, such conventional measures are typically unsatisfactory. The separation of the active substance, for example creaming or sedimentation of the active substance, may still occur, in particular if the aqueous formulation is stored for a relatively long time at elevated temperature and/or at highly variable temperatures or in the vicinity of the freezing point. This problem is particularly significant if the active substance has a tendency to crystallize.

WO2008/040786 disclosed a comb-copolymer, and the use of the comb-copolymer in stabilizing the aqueous phase that contains an insoluble or slightly soluble active substance, to obtain a stable aqueous formulation. The comb-copolymer is used as dispersant for dispersing and stabilizing the active substances that have been divided into small size, in water.

However, in the prior art, when polymer is used to prepare stable aqueous formulations of water insoluble or slightly soluble active substances, generally, said polymer is synthesized first, then such polymer is mixed with an active substance under certain conditions. In a formulation formed from the polymer and water insoluble or slightly soluble active substances, generally the interaction between the active substances and the polymer is weak, such that it is difficult for the active substances to be dispersed into the polymer matrix, in particular in the case of high level of loading of the active substances. Thus, in order to obtain the stability of the final formulation, the loading level of water insoluble or slightly soluble active substance in the formulation is significantly limited. The amount of active substance in given amount of stable formulation is very low. In addition, as the polymer has to be formed first, then mixed with active substance, the preparation process of the formulation according to the prior art is complicated, and is economically undesirable.

Surprisingly, the present invention solved the problems in the prior art by synthesizing a terpolymer and preparing a formulation based on the visco-elastic behavior of the macromolecule. In the formulations of the invention, there is a strong interaction between the inventive terpolymer and the active substance, thus for a given amount of formulation of the present invention, the loading level of the active substance can be substantively increased. The introduction of hydrophilic component in the terpolymer can shorten the interaction time among dispersed microparticles. More importantly, the introduction of hydrophobic component and a proper chain extension, not only the formation of the dispersed microparticles is induced and promoted, but also the relaxation time of the chains inside each microparticle is prolonged. With the change of the preparation conditions, different formulation forms such as emulsion or suspension are obtained, and the dispersion state of the formulations can be adjusted when the formulation is diluted with substantive amount of water. With these measures, the relaxation time of the chains inside the dispersed phase can be made much longer than the interaction time between the dispersed phases. In other words, within the relatively shorter interaction time, the dispersed phase is in glassy state which prevents aggregation, and thus enables the formation of a stable formulation system. The formulations can be prepared with simple procedures and easy to apply.

Detailed description of the invention

Formulation

In one aspect, the invention relates to a formulation comprising terpolymer and active substance (D), said terpolymer comprises main chain segment (A), hydrophobic pendent chains (B), and hydrophilic pendent chains (C).

For purpose of facilitating better understanding of the present invention, the formulation according to the invention is described as comprises core-shell particles formed by the terpolymer and the active substances (D), wherein the hydrophilic pendent chains (C) forms said shell, the hydrophobic pendent chains (B) forms said core, and said main chain segment (A) of the terpolymer combines with said active substance (D), and said active substance (D) is encapsulated between said core and said shell. However, the invention is not to be limited by this description. In other words, the said core-shell structure is only provided for the convenience of describing and understanding the invention, not for limiting the invention in any way.

Terpolymer

Structure of the inventive terpolymer comprises main chain segment (A), hydrophobic pendent chains (B) and hydrophilic pendent chains (C). The main chain segment (A) can be either hydrophobic or hydrophilic, depending on the condition. The molecular weight of the inventive terpolymer is at least 100,000 g/mol, preferably at least 150,000 g/mol, more preferably at least 200,000 g/mol, and at most 4,000,000 g/mol, preferably at most 3,000,000 g/mol, more preferably at most 2,000,000 g/mol, most preferably at most 1,000,000 g/mol. In a preferred embodiment of the invention, the molecular weight of the inventive terpolymer is l,300,000g/mol.

In the present invention, the main chain segment (A) interacts with the active substance (D) to weaken the aggregation tendency of the active substance (D), in particular the tendency of separating, crystallizing, flocculating or precipitating out of the system, so as to enables the formation of stable formulations.

In the present invention, preferably an environment sensitive component is used as the main chain segment (A), i.e., the main chain segment (A) will change its property (such as being hydrophilic or hydrophobic) under different conditions (such as changing in temperature and pH value). For example, the main chain segment (A) of the terpolymer which is formed with monomer (a) is hydrophobic under low pH conditions and may combine with the active substance (D), while being hydrophilic at high pH conditions and may release the active substance (D). This property of main chain segment (A) will help encapsulating said active substance (D) in the stable formulations under certain conditions, while releasing the active substance from the stable formulation under other conditions.

In general, said main chain segment (A) is derived from monomer (a), said hydrophobic pendent chain (B) is derived from monomer (b), and said hydrophilic pendent chain (C) is derived from monomer (c).

In a preferred embodiment of the present invention, monomers (a), (b) and (c) are copolymerized to form the inventive terpolymer. After the polymerization, the functional groups contained in monomer (a) will constitute the main chain segment (A) which in turn will complex with the active substance (D), while monomers (b) and (c) copolymerized into the main chain segment (A), and the groups contained in monomers (b) and (c) form the pendent chain (B) and (C) respectively. In this embodiment, pendent chains (B) and (C) are attached to the main chain segment (A) during the formation of the main chain segment (A).

Monomer (a) that contributes to the formation of the main chain segment (A) can be a member selected from the group consisting of (meth)acrylic acids, vinyl benzene sulfonic acid, vinyl pyridine, and N-isopropyl acrylamide, and the like. Monomer (b) that contributes to the formation of the hydrophobic pendent chain (B) can be for example a hydrophobic vinyl monomer, such as alkyl (meth)acrylate, styrene and/or vinyl acetate. When alkyl (meth)acrylate is used as monomer (b), the number of the carbon atom in the alkyl group is at least 8, preferably at least 10, more preferably at least 12, and at most 30, preferably at most 24, more preferably at most 20, and most preferably 18. Monomer (c) that contributes to the formation of the hydrophobic pendent chain (C) can be a member selected from the group consisting of for example (polyethylene glycol monomethylether) acrylate (i.e., PEG acrylate), acrylamide, vinylpyrrolidone, and N,N-dimethylacrylamide. When (polyethylene glycol monomethylether) acrylate (i.e., PEG acrylate) is used as Monomer (c), the molecular weight of the PEG is at least 500g/mol, preferably at least lOOOg/mol, and up to 8000g/mol, preferably up to lOOOOg/mol. The term "terpolymer" according to the invention does not exclude the presence of a small amount of other structures such as other hydrophobic pendent chains other than the hydrophobic pendent chain (B). One example of said other hydrophobic pendent chains is the ones that are derived from di(meth)acrylates.

With acrylic acid, C18 acrylate and PEG acrylate being used as monomers (a), (b) and (c), respectively, the terpolymer of the present invention can be illustrated as following.

(a) (b) (c)

Monomers (a) _^ (b) and (c)

terpolymer

In a further preferred embodiment, the hydrophobic pendent chain (B) and the hydrophobic pendent chain (C) constitute the chain of the terpolymer together with the main chain segment (A).

In the inventive terpolymer, the ratios between main chain segment (A), the hydrophobic pendent chain (B) and the hydrophilic pendent chain (C) influence the formation of hydrophobic core structure and hydrophilic shell structure as well as the loading of active substance (D) in said core-shell structure. Preferably in the inventive terpolymer, the amount of the main chain segment (A) is 17-60% by weight, the amount of the hydrophobic pendent chain (B) is 20-56% by weight, and the amount of the hydrophilic pendent chain (C) is 20-40% by weight, all based on the total weight of the terpolymer. Furthermore, based on the total weight of the terpolymer, less than 1.5% by weight of a di(meth)acrylate can be further added as a comonomer, such as ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, or polyethylene glycol di(meth)acrylate.

The structural unit of monomer (b) is randomly distributed along the main chain of the terpolymer. In case the Monomer (b) is an alkyl (meth)acrylate, each of the structural unit has a hydrocarbon type pendent chain of preferably more than 12 carbon atoms, more preferably each of the structural unit has a hydrocarbon type pendent chain of 12 -24 carbon atoms, more preferably 18 carbon atoms.

Active substance (D)

Active substances in the sense of the present invention are defined as substances that can manifest a particular activity or function or reactive under particular circumstance. The terms "active substance" and "effect substance" are used interchangeably and are synonymous in the context of this patent application. Examples of suitable active substance include small molecule active substance such as insecticides, acaricides, nematicides, fungicides and herbicides and growth regulators, and high molecular weight active substance such as proteins, RNA and DNA. Moreover, the inventive terpolymer can also be used to disperse and stabilize functional inorganic compounds, such as quantum-dots, as well as magnetic, light-emitting and catalytic substances, into polymeric core-shell particles.

For the purpose of the present invention, slightly soluble means a solubility of the active substance in water of less than 10 g/1, usually of less than 5 g/1 and in particular of less than 1 g/1 and especially of less than 0.1 g/1, at 25 ⁰ C and 1 atm (1013 mbar).

Manner of Incorporation

In the present invention, the interaction between the main chain segment (A) and the active substance (D) is strong that hinders the aggregation tendency of the active substance (D). Examples of such interaction include hydrogen bond, charge interaction, hydrophobicity interaction, etc.

The particle with core-shell structure formed according to the invention has the particle size and particle size distribution of from hundreds nanometers to tens of microns, more frequently from hundreds nanometers to several microns.

Loading of active substance (D) in the formulation according to the invention can be up to about 350% by weight based on the polymer used, and up to about 200mg/ml based on the solvent used. Preparation process of the formulation

Another aspect of the present invention relates to a process for the preparation of the inventive formulation. In a preferred embodiment of the present invention, said process include the steps of:

al) Dissolving monomers (a), (b) and (c) and active substance (D) in a solvent,

a2) In-situ copolymerization of monomers (a), (b) and (c) into the terpolymer in the presence of the solvent and the active substance (D), producing the inventive formulation comprising the terpolymer and the active substance (D).

The appearance of the obtained formulation can be clear and transparent, or can be a milky colloid.

The reaction type involved in above process is not critical to the implementation of the present invention. They can be any of commonly known reaction type, such as radical polymerization.

Various known initiators can be used in the polymerization, such as azo initiator, peroxide initiator and redox initiating system. Reaction temperature can be determined by those skilled in the art. In a preferred embodiment, the lower limit of the reaction temperature used in polymerization is O ⁰ C, preferably 2O ⁰ C, more preferable 3O ⁰ C, while the upper limit is 100 ⁰ C, preferably 8O ⁰ C, more preferably 7O ⁰ C, particular preferably 6O ⁰ C.

Solvent used in the process of the present invention is important for the implementation of the present invention. Said solvent must be able to dissolve all the reactant involved in the reactions and active substance (D), and essentially inert to the reactions. Said solvent preferably comprises ester of lower aliphatic carboxylic acid with lower aliphatic alcohol, such as ethyl acetate and butyl acetate.

pH vale of inventive formulation is preferably from about 1 to about 5.

Molar ratio of monomer (a) : monomer (b) : monomer (c) : active substance (D) in step a2) can be determined by a skilled person through experiments.

With the process of the present invention, stably dispersed inventive formulation could be obtained directly. For example, the formulation can be readily used after dilution 50-100 times with water.

Readv-for-use formulation comprising the inventive formulation

The present invention also relates to a process for the preparation of a ready-for-use formulation comprising the inventive formulation, said process including the step of mixing the inventive formulation with water, preferably 50-100 times of water.

In a preferred embodiment of the present invention, during the formation of the ready-for-use formulation, with the changing of the conditions (for example changing of pH value by way of water dilution), property of main chain segment (A) changes, thus achieving the goal of releasing the active substance (D).

Examples

The present invention is further illustrated by the following examples. These examples are for illustrative purpose only and can not be used to limit the scope of the present invention.

1. Preparation of the formulation of the present invention

Example 1

Epoxiconazole (EP), PEG acrylate, methacrylic acid (MAA), octodecyl acrylate (ODA) and azo-bis-isobutyronitrile (AIBN) were added into ethyl acetate (30 mL) according to the concentration as shown in Table 1 respectively, and homogenized with agitation. After that, a small amount of ethylene dimethacrylate (EDMA) was added to the polymerization mixture and the copolymerization was performed at 60 ⁰ C under nitrogen atmosphere for 24 h. The procedure was repeated five times with the changing of the amount of epoxiconazole (EP) to obtain five test samples 1-5 of the formulation. Table 1 shows the visual appearance of the formulation after polymerization.

Table 1 Dispersion copolymerization of MAA, ODA, PEG acrylate and EDMA (CEDMA = 0.6 mg/niL) in the presence of different amounts of epoxiconazole (CEP)

* A formulation with 66.7 g/1 epoxiconazole is obtainable from the polymerization of methacrylic acid (8.3 g/1), octodecyl acrylate (16.7 g/1), PEG acrylate (8.3 g/1) and a small amount of ethylene dimethacrylate (0.5 g/ml) in ethyl acetate. The formulation is a emulation and has no precipitate over 2 hours. After latex particles separated out, the system was in a homogeneous state with slight stirring.

**A formulation with 166.7 g/1 epoxiconazole is obtainable from the polymerization of methacrylic acid (26.7 g/1), octodecyl acrylate (16.7 g/1), PEG acrylate (8.3 g/1) and a small amount of ethylene dimethacrylate (0.6 g/ml) in ethyl acetate. The formulation has no aggregrative particle.

Example 2

Epoxiconazole (EP), PEG acrylate, methacrylic acid (MAA), octodecyl acrylate (ODA) and azo-bis-isobutyronitrile (AIBN) were added into ethyl acetate (20 ml) according to the concentration as shown in Table 2, and homogenized with agitation. The reaction was performed at 60 ⁰ C under nitrogen atmosphere for 24 h. The procedure was repeated five times with the changing of the amount of MAA to obtain five test samples 1-5 of the formulation. Table 2 shows the visual appearance of the formulation after polymerization.

Table 2. Dispersion copolymerization of MAA, PEG acrylate and ODA

2. Reparation of ready-for-use formulation of the present invention

Under magnetic stirring, the samples listed in Table 2 were added dropwise into distillated water at the volume ratio of the sample to water of 1:100. Sample A, sample B and sample C is obtained from Test 6, Test 9 and Test 8 in Table 2, respectively. Sample A-I, sample B-I and sample C-I are the mixture prepared by the re-dispersion of sample A, sample B and sample C in water, respectively.

Appearance of each thinned re-dispersion is shown in figure 1.