WO2020152360A1

WO2020152360A1 - Cationic polymer

Info

Publication number: WO2020152360A1
Application number: PCT/EP2020/051833
Authority: WO
Inventors: Francesco Trotta
Original assignee: Francesco Trotta
Priority date: 2019-01-24
Filing date: 2020-01-24
Publication date: 2020-07-30
Also published as: IT201900001071A1; EP3914625A1

Abstract

The present invention relates to a cationic polymer comprising: - at least one maltodextrin; - at least one substituent comprising at least one ammonium group; and - at least one linker covalently bonded to the at least one maltodextrin, wherein the at least one linker is selected from the group consisting of: dicarboxylic acid, dianhydride, carbonyldiimidazole, diphenylcarbonate, triphosgene, acylic dichloride, diisocyanate, a diepoxide, and a triepoxide. The present invention relates also to the preparation process of said cationic polymer and to its use for the purification of water.

Description

CATIONIC POLYMER

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DESCRIPTION

FIELD OF THE INVENTION The invention relates to a cationic polymer comprising a maltodextrin, its preparation processes and uses thereof.

BACKGROUND

Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids from water, to make it safe to drink or fit for a specific purpose in industry or medical applications.

Today, widely varied techniques are available to remove contaminants like fine solids, micro-organisms and some dissolved inorganic and organic materials, or environmental persistent pharmaceutical pollutants from waters. These methods include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination and the use of electromagnetic radiation such as ultraviolet light.

The choice of method depends, among others, on the quality of the water being treated, the cost of the treatment process, the quality standards expected of the processed water, as well as the specific type of contaminants that need to be removed.

Among the contaminants that need to be removed from waters, anions, such as nitrate, chromate, dichromate anions, arsenite, arseniate, glyphosate and colloidal particles are considered particularly relevant as they may have a negative effect on the health.

SUMMARY OF INVENTION

The Applicant has noted that, even if methods for water purification are widely available, they may present several limits and still need to be improved, in particular in terms of yield of removal of anions, such as nitrate, chromate and dichromate anions, and colloidal particles.

An object of the present invention is therefore the provision of a new and improved system for water purification suitable to effectively remove anions, such as nitrate, chromate and dichromate anions, and colloidal particles.

Therefore, the present invention relates, in a first aspect, to a cationic polymer comprising: - at least one maltodextrin; - at least one substituent comprising at least one ammonium group; and - at least one linker covalently bonded to the at least one maltodextrin, wherein the at least one linker is selected from the group consisting of: dicarboxylic acid, dianhydride, carbonyldiimidazole, diphenylcarbonate, triphosgene, acylic dichloride, diisocyanate, a diepoxide, and a triepoxide.

The Applicant has indeed noted that thanks to its structure incorporating a linker and positive charges, the cationic polymer according to the invention shows improved properties in the removal of anions, such as nitrates, chromates and dichromates from waste waters as well as in promoting the flocculation/sedimentation of colloidal particles from the same, thus resulting to be effective for water purification processes.

In particular, the Applicant has noted that colloidal particles have prevalently negative charge and that the same can be effectively removed by sedimentation once aggregated.

The Applicant has therefore observed that the cationic polymer according to the invention, due to its structure and to the high density of positive charges on its structure is effective for favoring the coagulation / flocculation process of such colloidal particles. The cationic polymer according to the invention has also the advantage of being based on a bio-based material generally biodegradable and biocompatible such as maltodextrins, which can be easily obtained and transformed from a natural resource widely available such as starch.

In a further preferred embodiment, the at least one linker is selected from the group consisting of: 1 ,T-carbonyldiimidazole, a diepoxide, and a triepoxide. More preferably, the at least one linker is selected from butanediol diglycidyl ether and trimethylol propane triglycidyl ether.

In a further aspect, the present invention also relates to a process for preparing the cationic polymer according to the invention, said process comprising the steps of: - providing at least one maltodextrin; - adding and reacting at least one compound comprising at least one ammonium group or an ammonium group precursor; - adding and reacting at least one linker compound selected from the group consisting of: dicarboxylic acid, dianhydride, carbonyldiimidazole, diphenylcarbonate, triphosgene, acylic dichloride, diisocyanate, and diepoxide; and - obtaining the cationic polymer.

The process according to the present invention allows obtaining, starting from the aforesaid bio-based material, non-toxic and biocompatible cationic polymers with predetermined positive charge density, using a simple and efficient synthetic procedure that, advantageously, may not require the use of organic solvents. In another aspect, the present invention relates to a cationic polymer obtainable by said process according to the present invention.

In a further aspect, the present invention relates therefore to the use of the cationic polymer according to the invention for the purification of water.

The advantages of this use have been already outlined with reference to the cationic polymer according to the invention and are not repeated herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the FTIR-ATR spectrum of the cationic polymer according to Example 1 ;

Figure 2 shows the TGA thermogram of the cationic polymer according to Example 1 ;

Figure 3 shows the FTIR-ATR spectrum of the cationic polymer according to Example 2; Figure 4 shows the TGA thermogram of the cationic polymer according to Example

2;

Figure 5 shows the FTIR-ATR spectrum of the cationic polymer according to Example 4; Figure 6 shows the TGA thermogram of the cationic polymer according to Example

4;

Figure 7 shows the FTIR-ATR spectrum of the cationic polymer according to Example 7;

Figure 8 shows the TGA thermogram of the cationic polymer according to Example 7;

Figure 9 shows the FTIR-ATR spectrum of the cationic polymer according to Example 9;

Figure 10 shows the TGA thermogram of the cationic polymer according to Example 13; and Figure 11 shows the FTIR-ATR spectrum of the cationic polymer according to Example 13.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates, in a first aspect, to a cationic polymer comprising: - at least one maltodextrin; and - at least one substituent comprising at least one ammonium group; and - at least one linker covalently bonded to the at least one maltodextrin, wherein the at least one linker is selected from the group consisting of: dicarboxylic acid, dianhydride, carbonyldiimidazole, diphenylcarbonate, triphosgene, acylic dichloride, diisocyanate, a diepoxide, and a triepoxide.

Thanks to its structure comprising the combination of specific components, namely at least one maltodextrin, at least one substituent comprising at least one ammonium group, and at least one linker, the cationic polymer according to the invention shows improved properties in the removal of anions, such as nitrates, chromates and dichromate anions from waste waters as well as in promoting the flocculation/sedimentation of colloidal particles from the same, thus resulting to be effective for water purification processes.

The Applicant has therefore observed that the cationic polymer according to the invention, due to its structure and to the high density of positive charges on its structure is effective for favoring the coagulation / flocculation process of such colloidal particles. Being based on a bio-based material generally biodegradable and biocompatible, the cationic polymer according to the invention has also the advantage of being easily obtained and transformed from a natural resource widely available such as starch. Thanks to these properties, the cationic polymer according to the invention may be used without drawbacks linked to its final disposal or to the contact with the environment.

Within the framework of the present description and in the subsequent claims, except where otherwise indicated, all the numerical entities expressing amounts, parameters, percentages, and so forth, are to be understood as being preceded in all instances by the term "about". Also, all ranges of numerical entities include all the possible combinations of the maximum and minimum values and include all the possible intermediate ranges, in addition to those specifically indicated herein below.

The present invention may present in one or more of the above aspects one or more of the characteristics disclosed hereinafter. The expression“maltodextrin” classically refers to the starchy material obtained by acid and/or enzymatic hydrolysis of starch.

Preferably, the maltodextrin useful to the invention has a DE chosen in the range of 2 to 50, preferably of 5 to 50, preferably of 10 to 40, preferably of 15 to 35, preferably of 15 to 30, preferably of 15 to 20. This DE is for instance equal to 2 or to 17. Preferably, the maltodextrin useful to the invention is derived from starch comprising 25 to 50 % of amylose, expressed as dry weight relative to the total dry weight of said starch.

This amylose content can be classically determined by the person skilled in the art by way of potentiometric analysis of iodine absorbed by amylose to form a complex.

Preferably, the maltodextrin useful to the invention is derived from a starch exhibiting an amylose content chosen within the range of 25 to 50 %, preferably of 30 to 45 %, preferably of 35 to 40 %; these percentages being expressed in dry weight of amylose with respect to the total dry weight of starch. It is reminded that the expression“starch” classically refers to the starch isolated from any suitable botanical source, by any technique well known to those skilled in the art. Isolated starch typically contains no more than 3 % of impurities; said percentage being expressed in dry weight of impurities with respect to the total dry weight of isolated starch. These impurities typically comprise proteins, colloidal matters and fibrous residues. Suitable botanical source includes for instance legumes, cereals, and tubers. In this regard, the starch of the invention is preferably a legume starch, even more preferably a pea starch, even more preferably a smooth pea starch.

Preferably, the maltodextrin useful to the invention has a weight average molecular weight chosen within the range of 1 000 to 300.000 daltons (Da), 5 000 to 100.000 Da, preferably of 10 000 to 15 000 Da, preferably of 10 000 to 14 000, for instance equal to 12 000 Da.

This weight average molecular can in particular be determined by the person skilled in the art by liquid chromatography with detection by differential refractometer, preferably by using pullulan standards.

The maltodextrin useful to the invention is obtained by hydrolysis of starch, but might has undergone other chemical and/or physical modification, as long as it does not interfere with the desired properties, notably in term of safety and efficiency of the final cross-linked maltodextrin. However, and because it appears that it is not necessary in the present invention, the maltodextrin useful to the invention is preferably no further modified.

Suitable maltodextrins are commercially available, for instance those marketed under the name KLEPTOSE® Linecaps (ROQUETTE), Glucidex® (ROQUETTE), Stabilys® (ROQUETTE) e Tackidex® (ROQUETTE).

The cationic polymer according to the invention comprises at least one substituent comprising at least one ammonium group.

Preferably, the at least one ammonium group is a quaternary ammonium group.

Preferably, the at least one substituent comprising at least one ammonium group is covalently bonded to at least maltodextrin. More preferably, the at least one substituent comprising at least one ammonium group is covalently bonded to a hydroxyl group of the at least one maltodextrin. Even more preferably, the at least one substituent comprising at least one ammonium group is covalently bonded to a primary hydroxyl group of the at least one maltodextrin. Preferably, the at least one substituent comprising at least one ammonium group is selected from the group consisting of:

wherein

- Ri is a C1-C3 alkylene moiety, optionally substituted with a group selected from OH and C1-C3 alkyl; and

- R2, R3, R4 are indepentently selected from the group consisting of: H, CH3, CH2-CH3, CH2-CH2-CH3, and CH(CH₃)2.

More preferably, the at least one substituent comprising at least one ammonium group is selected from the group consisting of:

Preferably, the at least one substituent comprising at least one ammonium group is selected from the group consisting of:

The cationic polymer according to the invention comprises at least one linker covalently bonded to the at least one maltodextrin, wherein the at least one linker is selected from the group consisting of: dicarboxylic acid, dianhydride, carbonyldiimidazole, diphenylcarbonate, triphosgene, acylic dichloride, diisocyanate, a diepoxide, and a triepoxide.

Said at least one linker, thanks to its reactivity with the other components of the cationic polymer, decisively contributes to the structure of the cationic polymer itself reacting through different mechanisms, which may be in place all at the same time. For example, the at least one linker is capable to covalently bind the at least one maltodextrin to the at least one substituent comprising at least one ammonium group. At the same time, the at least one linker may also covalently bind a reactive group of the at least one maltodextrin, for example an hydroxyl group, to another reactive group of the same at least one maltodextrin, for example a different hydroxyl group. In this way, the at least one linker acts, for example, creating a further covalent bond within the same same maltodextrin. In addition, the at least one linker, when said cationic polymer comprises at least two maltodextrin, is also suitable to covalently bind said at least two maltodextrin one to another. In this case, for example, said at least one linker may covalently bind, through a reactive group of a first maltodextrin, for example a hydroxyl group, to a reactive group of a second maltodextrin, for example a hydroxyl group.

Preferably, in the cationic polymer according to the present invention the at least one linker is selected from the group consisting of: a dicarboxylic acid, a dianhydride, carbonyldiimidazole and, diisocyanate, a diepoxide, and a triepoxide.

Among the dicarboxylic acids, in the present invention the following diacids can be used: polyacrylic acid, butane tetracarboxylic acid, succinic acid, tartaric acid and citric acid. More preferably the at least one linker is citric acid. In an advantageous embodiment the cationic polymer comprises citric acid and tartaric acid as linkers. Among the dianhydrides, in the present invention the following dianhydrides can be used: diethylenetriaminepentaacetic dianhydride, ethylenediaminetetraacetic dianhydride, benzophenone-3,3',4,4'-tetracarboxylic dianhydride, and pyromellitic dianhydride. More preferably the at least one linker is pyromellitic dianhydride.

Among the acylic chlorides, in the present invention the following acylic chlorides can be used: terephthaloyl chloride, sebacoil sebacoyl chloride, succinyl chloride. More preferably the at least one linker is terephthaloyl chloride.

Among the diisocyanates, in the present invention the following diisocyanates can be used: toluenediisocyanate, Isophorone diisocyanate, 1 ,4-Phenylene diisocyanate, Poly(hexamethylene diisocyanate), and hexamethylene diisocyanate. More preferably the at least one linker is hexamethylene diisocyanate.

More preferably, the at least one linker is selected from the group consisting of: pyromellitic dianhydride, 1 ,1’-carbonyldiimidazole, hexamethylene diisocyanate, citric acid, tartaric acid, a diepoxide, and a triepoxide.

In a preferred embodiment, the at least one linker is selected from the group consisting of: 1 ,1’-carbonyldiimidazole, a diepoxide, and a triepoxide. More preferably, the at least one linker is selected from butanediol diglycidyl ether and trimethylol propane triglycidyl ether.

Preferably, in the cationic polymer according to the invention the molar ratio between the at least one linker and the at least one substituent comprising at least one ammonium group is from 0.5 to 5.

Depending on the molar ratio between the at least one linker and the at least one substituent comprising at least one ammonium group, the cationic polymer according to the invention may show a broad range of degrees of branching and charge densities. In a preferred embodiment, the molar ratio between the at least one linker and the at least one substituent comprising at least one ammonium group is from 0.5 to 0.8. In this way, the cationic polymer according to the invention is a hyperbranched polymer, at the same time being a polymer soluble in water. In the context of the present invention, the expression“hyperbranched polymer” means that the polymer has a structure in which the amount of linker is lower than the amount of the substituent comprising at least one ammonium group, and the expression“polymer soluble in water” means a polymer having a solubility higher than 50% by weight in water, said solubility being measured by immersing a sample of the polymer in water at 25 °C and at concentration of 0.005 g/ml and maintaining the sample under stirring for a time of at most 12 hours.

In a further preferred embodiment, the molar ratio between the at least one linker and the at least one substituent comprising at least one ammonium group is from 1 to 5. In this way, the cationic polymer according to the invention shows a cross- linked structure. Polymers having such a structrure are referred to also as “nanosponges”.

Preferably, the cationic polymer according to the invention further comprises: - at least one cyclodextrin unit. More preferably, the at least one cyclodextrin unit is selected from the group consisting of: a-cyclodextrin, b-cyclodextrin, g-cyclodextrin, or a derivative thereof. Preferably, said derivative of said cyclodextrin is selected from the group consisting of: hydroxypropyl- -cyclodextrin (HP- b -CD) and sulfobutyl ether- b -cyclodextrin (SBE- b-CD).

In a preferred embodiment, the at least one cyclodextrin unit is a b-cyclodextrin unit. Preferably, the nitrogen content of the cationic polymer is from 0.5 to 8.0 wt%.

Said nitrogen content may advantageosly be determined by elemental analysis technique with combustion method, preferably a flash dynamic combustion method. The elemental analysis for determining the nitrogen content of the cationic polymer according to the invention may be for example performed using a Thermo Fisher FlashEA 1112 Series.

The process according to the present invention allows obtaining, starting from the aforesaid bio-based material, non-toxic and biocompatible cationic polymers with controllable positive charge density, using a simple synthetic procedure that advantageously does not require the use of organic solvents.

When in the process according to the present invention a compound comprising at least one ammonium group precursor is used, the ammonium group is formed during the reaction.

Preferably, the molar ratio between the at least one maltodextrin and the at least one compound comprising at least one ammonium group or an ammonium group precursor is of from 0.05 to 2. Advantageously, the process according to the invention provides for adding and reacting the at least one linker compound together with the at least one compound comprising at least one ammonium group or an ammonium group precursor.

Preferably, the molar ratio between the at least one maltodextrin and the at least one linker compound is of from 0.1 to 1.

Preferably, the molar ratio between the at least one linker compound and the at least one compound comprising at least one ammonium group or an ammonium group precursor is of from 0.5 to 5.

Preferably, the at least one compound comprising at least one ammonium group or an ammonium group precursor is selected from the group consisting of:

diazabiciclo[2.2.2]octane (DABCO)

wherein

- Ri is a C1-C3 alkylene moiety, optionally substituted with a group selected from OH and C1-C3 alkyl;

- R2, R3, R4 are indepentently selected from the group consisting of: H, CH3,

CH2-CH3, CH2-CH2-CH3, and CH(CH₃)₂;

- X is a monovalent anion, preferably selected from the group consisting of Cl, Br, I or OH.

More preferably, the at least one compound comprising at least one ammonium group or an ammonium group precursor is selected from the group consisting of:

diazabiciclo[2.2.2]octane (DABCO)

wherein

X is a monovalent anion, preferably selected from the group consisting of Cl, Br, I or OH.

In a preferred embodiment, in the process according to the invention, at least one compound comprising at least one ammonium group precursor is used. Preferably, said compound comprising at least one ammonium group precursor is diazabiciclo[2.2.2]octane (DABCO).

When in the process according to the present invention DABCO is used as ammonium group precursor, the inventors surprisingly found out that the ammomium group is formed during the reaction.

Preferably, the at least one compound comprising at least one ammonium group is selected from the group consisting of:

x (XVIII)

Preferably, the process according to the invention comprises also the step of: - adding and reacting at least one nucleophilic compound selected from the group consisting of: tosylate, amine, halogen compound.

Preferably, said step of adding and reacting at least one nucleophilic compound is carried out before the step of adding and reacting at least one compound comprising at least one ammonium group or an ammonium group precursor.

Preferably, the process according to the invention comprises also the step of: - adding and reacting at least one cyclodextrin.

Advantageously, the process according to the invention provides for adding and reacting the at least one cyclodextrin together with the at least one maltodextrin.

In a first preferred embodiment, the process according to the invention comprises the steps of: a1. providing at least one maltodextrin; b1. adding to and reacting with the at least one maltodextrin of step a1. the at least one compound comprising at least one ammonium group or an ammonium group precursor together with the at least one linker compound; and c1. obtaining the cationic polymer from step b1.

In a second preferred embodiment, the process according to the invention comprises the steps of: a2. providing at least one maltodextrin; b2. adding to and reacting with the at least one maltodextrin of step a2. the at least one compound comprising at least one ammonium group or an ammonium group precursor, to obtain a maltodextrin derivative, said maltodextrin derivative being substituted with at least one substituent comprising at least one ammonium group or an ammonium group precursor; c2. adding to and reacting with the maltodextrin derivative of step b2. the at least one linker compound; and d2. obtaining the cationic polymer from step c2.

In a third preferred embodiment, the process according to the invention comprises the steps of: a3. providing at least one maltodextrin; b3. adding to and reacting with the at least one maltodextrin of step a3. at least one nucleophilic compound selected from the group consisting of: tosylate, amine, halogen compound, to obtain a first maltodextrin derivative; c3. adding to and reacting with the first maltodextrin derivative of step b3. the at least one compound comprising at least one ammonium group or an ammonium group precursor, to obtain a second maltodextrin derivative, said second maltodextrin derivative being substituted with at least one substituent comprising at least one ammonium group or an ammonium group precursor; d3. adding to and reacting with the second maltodextrin derivative of step c3. the at least one linker compound; and e3. obtaining the cationic polymer from step d3.

In a fourth a preferred embodiment, the process according to the invention comprises the steps of: a4. providing at least one maltodextrin; b4. adding to and reacting with the at least one maltodextrin of step a4. at least one nucleophilic compound selected from the group consisting of: tosylate, amine, halogen compound, to obtain a first maltodextrin derivative; c4. adding to and reacting with the first maltodextrin derivative of step b4. the at least one compound comprising at least one ammonium group or an ammonium group precursor together with the at least one linker compound; and d4. obtaining the cationic polymer from step c4. In a fifth preferred embodiment, the process according to the invention comprises the steps of: a5. providing at least one maltodextrin; b5. adding to and reacting with the at least one maltodextrin of step a5. at least one nucleophilic compound selected from the group consisting of: tosylate, amine, halogen compound, to obtain a first maltodextrin derivative; c5. adding to and reacting with the first maltodextrin derivative of step b5. the at least one linker compound, to obtain a maltodextrin polymer; d5. adding to and reacting with the maltodextrin polymer of step c5. the at least one compound comprising at least one ammonium group or an ammonium group precursor; and e5. obtaining the cationic polymer from step d5.

In another aspect, the present invention relates to a cationic polymer obtainable by said process according to the present invention. The cationic polymer according to the invention shows improved properties in the removal of anions, such as nitrates, chormates and dichromates, from waters as well as in promoting the flocculation/sedimentation of colloidal particles from the same, thus resulting to be effective for water purification processes.

Further features and advantages of the invention will appear more clearly from the following description of some preferred embodiments thereof, made hereinafter by way of a non-limiting example with reference to the following exemplary examples.

EXPERIMENTAL PART

Example 1 In a 50 ml flask containing 24 ml of anhydrous dimethylformamide, 4.00 grams (0.022 moles) of anhydrous maltodextrin (KLEPTOSE® Linecaps) were solubilized. Then 0.98 grams (0.007 moles) of anhydrous choline chloride and 2.28 grams (0.014 moles) of 1 ,T-carbonyldiimidazole were added. The solution thus obtained was kept under stirring at 90 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder. Figure 1 shows the FTIR-ATR spectrum of the cationic polymer thus obtained, and Figure 2 shows the TGA thermogram of the same, obtained according to the following methods.

FTIR-ATR

All the spectra were collected in the 650-4000 cm-1 wavenumber range, at room temperature, with a resolution of 4 cm-1 and 8 scans/spectrum. A Perkin Elmer Spectrum 100 FT-IR Spectrometer equipped with an Universal ATR Sampling Accessory was used.

TGA

Thermogravimetric analysis were carried out using a TA Instruments Q500 TGA, from 50 to 700 °C, under nitrogen flow, with an heating rate of 10 °C/min.

Example 2

In a 250 ml flask containing 100 ml of dimethyl sulfoxide, 6.00 grams (0.033 moles) of anhydrous maltodextrin (KLEPTOSE® Linecaps) were solubilized. Then 6 grams (0.043 moles) of anhydrous choline chloride 12,5 ml (0.09 moles) di triethylamine and 9,40 grams (0.043 moles) of pyromellytic anyhidride were added. The solution thus obtained was kept under stirring at 25 °C for 2 hour until a gel was obtained. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder. Figure 3 shows the FTIR- ATR spectrum of the cationic polymer thus obtained, and Figure 4 shows the TGA thermogram of the same, obtained according to the method disclosed in Example 1 .

Gravimetric analysis confirmed a synthetis yield of 80 %, calculated by considering the weight of the product with respect to the theoretical weight, equal to the sum of the reactants.

Example 3

In a 50 ml flask containing 24 ml of anhydrous dimethylformamide, 4.00 grams (0.022 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 1.96 grams (0.014 moles) of anhydrous choline chloride and 4.56 grams (0.028 moles) of 1 ,T-carbonyldiimidazole were added. The solution thus obtained was kept under stirring at 70 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder.

Example 4

In a 250 ml flask containing 110 ml of dimethyl sulfoxide, 18.00 grams (0.1 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 9 grams (0.064 moles) of anhydrous choline chloride 27.00 grams (0.13 moles) of diphenylcarbonate were added. The solution thus obtained was kept under stirring at 90 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder. Figure 5 shows the FTIR- ATR spectrum of the cationic polymer thus obtained, and Figure 6 shows the TGA thermogram of the same, obtained according to the method disclosed in Example 1 . Gravimetric analysis confirmed a synthetis yield of 80 %, calculated by considering the weight of the product with respect to the theoretical weight, equal to the sum of the reactants.

The cationic polymer was then characterized to determine its solubility in water, dimethyl sulphoxide, in ethanol and in hexane.

Solubility test

For the solubility test, a sample of the polymer was immersed in the solvent at 25 °C and at concentration of 0.005 g/ml.

The solubility and swelling of the polymer was determined either immediately after immersion (time = 0) and after 12 hours, during which the system was maintained under stirring (time =12 hours).

The polymer was considered soluble when at least 50% by weight of the same was found to be dissolved, and swellable when, at the time of the observation, it changed in linear dimensions or through volumetric change. In Table 1 ,“YES” and“NO” respectively means that the polymer was, or was not, soluble or swellable according to this definition.

Table 1 shows the solubility in water, dimethyl sulphoxide, in ethanol and in hexane.

TABLE 1

Example 5

In a 100 ml flask containing 30 ml of dimethyl sulfoxide, 10.00 grams (0.055 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 13.00 grams (0.093 moles) of anhydrous choline chloride 250 mg (0.0018 moles) of 1 ,5,7- triazabicyclo[4.4.0]dec-5-ene, and then 20 ml (0.24 moles) of dimethylcarbonate were added. The solution thus obtained was kept under stirring at 80 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder.

Gravimetric analysis confirmed a synthetis yield of 30 %, calculated by considering the weight of the product with respect to the theoretical weight, equal to the sum of the reactants. Example 6

In a 50 ml flask containing 8 ml of an aqueous NaOH solution (0.2M), 2.00 grams (0.011 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 0.98 (0.007 moles) grams of anhydrous choline chloride and 5.34 ml (0.028 moles) of 1 ,4-butanediol diglycidyl ether were added. The solution thus obtained was kept under stirring at 90 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder. Gravimetric analysis confirmed a synthetis yield of 50 %, calculated by considering the weight of the product with respect to the theoretical weight, equal to the sum of the reactants.

Example 7

In a 50 ml flask containing 6 ml of an aqueous NaOH solution (0.2M), 2.00 grams (0.011 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 3.70 (0.026 moles) grams of anhydrous choline chloride and 400 mg (0.0035 moles) of diazabiciclo[2.2.2]octane and then 7.00 ml (0.027 moles) of trimethylol propane triglycidyl ether were added. The solution thus obtained was kept under stirring at 100 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder.

Figure 7 shows the FTIR-ATR spectrum of the cationic polymer thus obtained, and Figure 8 shows the TGA thermogram of the same, obtained according to the method disclosed in Example 1.

Gravimetric analysis confirmed a synthetis yield of 60 %, calculated by considering the weight of the product with respect to the theoretical weight, equal to the sum of the reactants. The cationic polymer was then characterized to determine its elemental composition, its solubility in water, dimethyl sulphoxide, in ethanol and in hexane.

Elemental composition

The elemental composition has been determined by means of Flash Dynamic Combustion Method using a Thermo Fisher FlashEA 1112 Series. Table 2 shows the elemental analysis of the polymer

TABLE 2

Solubility test

Table 3 shows the solubility in water, dimethyl sulphoxide, in ethanol and in hexane, carried out according to the method disclosed in Example 4. TABLE 3

Example 8

In a 50 ml flask containing 24 ml of anhydrous dimethylformamide, 4.00 grams (0.022 moles) of anhydrous maltodextrin (GLUCIDEX® 39) were solubilized. Then

1.96 grams (0.014 moles) of anhydrous choline chloride and 4.56 grams (0.028 moles) of 1 ,T-carbonyldiimidazole were added. The solution thus obtained was kept under stirring at 70 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, followed by a further washing with acetone, so as to remove any non reacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder.

Example 9

In a 250 ml flask containing 100 ml of deionized water, 4.00 grams (0.022 moles) of anhydrous maltodextrin (KLEPTOSE® Linecaps) were solubilized. Then 5.57 grams (0.028 moles) of carnitine chloride were added. The solution thus obtained was kept at 80 °C for 15 hour in vacuum (around 20 torr) until complete elimination of the solvent (water) and then left cool to ambient temperature. The product is then solubilized in deionized water and filterd with a membrane (cut off 3 kDA), so as to remove any non reacted reagent. The product was then liophylized. A white powder was obtained. Figure 9 shows the FTIR-ATR spectrum of the cationic polymer thus obtained, obtained according to the method disclosed in Example 1. The cationic polymer was then characterized to determine its elemental composition, according to the method disclosed in Example 7.

Elemental composition

Table 4 shows the elemental analysis of the polymer. TABLE 4

Example 10

In a 10 ml flask containing 6 ml of anhydrous dimethyl sulfoxide, 1.00 grams (0.005 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 68 pi (0.0009 moles) of 2-iodoethanol, 134 mI (0.001 moles) of triethylamine, and 572 mg

(0.0035 moles) of 1 ,T-carbonyldiimidazole were added. The solution thus prepared was kept under stirring at 90 °C for 1.5 hours until a gel was obtained and then left cool to ambient temperature. After usual work up the product was freeze dryed and to get a pale yellow powder. Example 11

In a 10 ml flask containing 6 ml of anhydrous dimethyl sulfoxide, 1.00 grams (0.005 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then 68 mI (0.0009 moles) of 2-iodoethanol, and 572 mg (0.0035 moles) of 1 ,1’- carbonyldiimidazole were added. The solution thus prepared was kept under stirring at 90 °C for 1.5 hours until a gel was obtained and then left cool to ambient temperature. After usual work up the product was freeze dryed to get a pale yellow powder. Subsequentely, the insoluble powder was put in a water solution of trimethylamine for 24 hours, the solid was recovered by filtration and dryed to obtain the corresponding positive nanosponge. Example 12 In order to investigate the use of the cationic polymer according to the invention for the purification of water, the polymers according to Examples 4, 5, 6, and 7 were used to perform removal test from samples of water containing different amounts of anions, such as nitrate, chromate and dichromate anions. Nitrates removal test

1 g of cationic polymer is dispersed in 100 ml of a 100 ppm KNCb aqueous solution. The removal was evaluated after 24 hours on the aqueous solution after separation of the cationic polymer, by using a Metrohm 883 Basic IC plus ion chromatography system. Chromates and dichromate removal test

1 g of cationic polymer is dispersed in 100 ml of a 100 ppm foCrC solution. The removal was evaluated after 24 hours on the aqueous solution after separation of the cationic polymer, by using a Metrohm 883 Basic IC plus ion chromatography system. Table 5 shows the performances in terms of removal of anions, such as nitrate, chromate and dichromate anions of the cationic polymers according to Examples 4, 5, 6, and 7 for a solution containing 100 ppm of nitrates and for a solution containing 100 ppm of chromates, in terms of percentage of removal and of milligrams of anion removed for grams of polymer added to the solution. TABLE 5

Example 13

In a 50 ml flask containing 10 ml of an aqueous NaOH solution (0.2M), 3.50 grams (0.019 moles) of anhydrous maltodextrin (GLUCIDEX® 2) were solubilized. Then

0.25 (0.002 moles) grams of diazabiciclo[2.2.2]octane (DABCO) and 0.72 ml (0.004 moles) of 1 ,4-butanediol diglycidyl ether (BDE) were added. The solution thus obtained was kept under stirring at 90 °C for 1 hour until a gel was obtained and then left cool to ambient temperature. The reaction product was recovered from the flask and subsequently washed with water, so as to remove any unreacted reagent and solvent. At the end of the washing step, the product was dried and then ground with a ball mill, thus obtaining a brown powder.

Figure 10 shows the TGA thermogram of the cationic polymer thus obtained, and Figure 11 shows the FTIR-ATR spectrum of the same, obtained according to the method disclosed in Example 1.

Gravimetric analysis confirmed a synthesis yield of 75 %, calculated by considering the weight of the product with respect to the theoretical weight, equal to the sum of the reactants.

The cationic polymer was then characterized to determine its elemental composition, zeta-potential, thermal stability, its solubility in water, dimethyl sulphoxide, in ethanol and in hexane.

Elemental composition

The elemental composition was determined according to the method disclosed in Example 7 by means of Flash Dynamic Combustion Method using a Thermo Fisher FlashEA 1112 Series.

Table 6 shows the elemental analysis of the polymer.

TABLE 6

Zeta-potential

The zeta-potential has been determined by means of a Malvern Zetasizer Nano - ZS. Table 7 shows the elemental analysis of the polymer.

TABLE 7

Solubility test

Table 8 shows the solubility in water, dimethyl sulphoxide, in ethanol and in hexane, carried out according to the method disclosed in Example 4.

TABLE 8

Claims

1. A cationic polymer comprising:

- at least one maltodextrin;

- at least one substituent comprising at least one ammonium group; and - at least one linker covalently bonded to the at least one maltodextrin, wherein the at least one linker is selected from the group consisting of: dicarboxylic acid, dianhydride, carbonyldiimidazole, diphenylcarbonate, triphosgene, acylic dichloride, diisocyanate, a diepoxide, and a triepoxide.

2. Cationic polymer according to claim 1 , wherein the at least one maltodextrin has a DE chosen in the range of 2 to 50.

3. Cationic polymer according to claim 1 or 2, wherein the at least one maltodextrin is derived from starch comprising 25 to 50 % of amylose, expressed as dry weight relative to the total dry weight of said starch.

4. Cationic polymer according to any one of claims from 1 to 3, wherein the at least one maltodextrin has a weight average molecular weight chosen within the range of

1 000 to 300.000 daltons (Da).

5. Cationic polymer according to any of claims from 1 to 4, wherein the at least one substituent comprising at least one ammonium group is covalently bonded to the at least one maltodextrin.

6. Cationic polymer according to any of claims from 1 to 5, wherein the at least one substituent comprising at least one ammonium group is selected from the group consisting of:

wherein

7. Cationic polymer according to claim 6, wherein the at least one substituent comprising at least one ammonium group is selected from the group consisting of:

8. Cationic polymer according to anyone of claims from 1 to 7, wherein said at least one linker covalently binds said maltodextrin to the at least one substituent comprising at least one ammonium group, and/or covalently binds a reactive group of the at least one maltodextrin to another reactive group of the same at least one maltodextrin, and/or wherein said cationic polymer comprises at least two maltodextrin and said at least one linker covalently binds said at least two maltodextrin one to another.

9. Cationic polymer according to claim 8, wherein the at least one linker is selected from the group consisting of: 1 , 1’-carbonyldiimidazole, a diepoxide, and a triepoxide.

10. Cationic polymer according to claim 8 or 9, wherein the molar ratio between the at least one linker and the at least one substituent comprising at least one ammonium group is from 0.5 to 5.

11. Cationic polymer according to any one of claims from 1 to 10, wherein the nitrogen content of the cationic polymer is from 0.5 to 8.0 wt%.

12. A process for preparing the cationic polymer according to any one of claims from 1 to 11 , said process comprising the steps of: - providing at least one maltodextrin;

- adding and reacting at least one compound comprising at least one ammonium group; and

- obtaining the cationic polymer.

13. A cationic polymer obtainable by the process according to claim 12.

14. Use of the cationic polymer according to any one of claims 1 to 11 or 13, for the purification of water.