Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a high-molecular-weight multi-arm anionic-nonionic polymer dispersant, which improves the steric hindrance effect by increasing polymer chains, avoids the dispersion effect influenced by the entanglement among the molecular chains, and provides more anchoring groups with higher molecular weight.
In order to achieve the purpose, the invention provides the following technical scheme:
an anionic-nonionic dispersant is a macromolecular anionic-nonionic dispersant shown in formula 2) which is obtained by modifying hydroxyl groups at two ends of polyethylene glycol to obtain a reactive anionic-nonionic monomer shown in formula 1) and then synthesizing under an ATRP four-head initiator;
wherein n is an integer of 5 to 20,
represents a polymer chain of the formula 1).
The present invention further provides a method for preparing the anionic-nonionic dispersant as described above, which comprises the steps of:
s1: adding polyethylene glycol and dichloromethane into a reaction bottle, stirring to uniformly mix, adding a catalytic amount of silver oxide/potassium iodide catalyst, adding paratoluensulfonyl chloride with the same molar amount as the polyethylene glycol, stirring to react for 2-3 h at room temperature, and filtering and washing to obtain TsO-PEG-OH;
s2: dissolving TsO-PEG-OH in 25% ammonia water, adding equimolar ammonium chloride, stirring at 30 deg.C for 3 days, extracting with dichloromethane, and purifying the collected organic layer by column chromatography to obtain NH2-PEG-OH;
S3: the obtained NH2-PEG-OH was dissolved in deionized water and addedAdjusting the pH value of equimolar benzaldehyde-4-sodium sulfonate to 6.5 to obtain a mixed solution, dropwise adding sodium amino borohydride into the mixed solution, stirring and reacting at room temperature for 12 hours, and dialyzing, freezing and drying the reaction solution to obtain a solid; dissolving the solid in toluene, adding a polymerization inhibitor hydroquinone, a catalyst p-toluenesulfonic acid and monomer acrylic acid, heating to 110-120 ℃, stirring and refluxing for 4 hours, washing with a saturated sodium carbonate solution, separating liquid, performing rotary evaporation on an organic layer to remove the solvent, and recrystallizing to obtain the reactive anionic-nonionic monomer shown in the formula 1);
s4: adding pentaerythritol, triethylamine and anhydrous dioxane into a reaction bottle, introducing nitrogen to replace air in the reaction bottle, placing the reaction bottle in an environment at-18 ℃, dropwise adding a tetrahydrofuran solution of 2-bromoisobutyryl bromide in a nitrogen atmosphere, and after dropwise adding, moving the reaction bottle to room temperature to react for 12 hours under stirring; extracting with dichloromethane, collecting an organic layer, washing, drying, rotary steaming and recrystallizing to obtain an ATRP four-head initiator;
s5: sequentially adding a catalyst, a coordination agent, the ATRP four-head initiator and a reactive anionic-nonionic monomer into a schlenk bottle, adding tetrahydrofuran, stirring to dissolve and mix the tetrahydrofuran uniformly, filling nitrogen into the schlenk bottle through three cycles of freezing, air extraction, thawing and inflation, and reacting for 2-5 hours at 60 ℃; after the reaction is finished, adding tetrahydrofuran for dissolving and diluting, and then precipitating and separating out a polymer in a large amount of n-hexane after passing through neutral alumina, thus obtaining the anionic-nonionic dispersing agent.
Further, the catalyst is cupric bromide, cuprous bromide or a mixture of the cupric bromide and the cuprous bromide; the complexing agent is bipyridine or N, N, N' -pentamethyldiethylenetriamine.
Furthermore, the feeding molar ratio of the catalyst, the complexing agent, the ATRP four-head initiator and the reactive anionic-nonionic monomer is 1:2:1: 50-100.
The invention has the beneficial effects that: the dispersant prepared by the invention has the characteristics of negative and non-ionic property, is suitable for different solution systems, can be used for dispersing inorganic pigments or organic pigments, and has the advantages of good stability, low surface tension and critical micelle concentration and high dispersibility.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides a preparation method of an anionic-nonionic dispersant, which comprises the following steps:
s1: adding polyethylene glycol (PEG) and dichloromethane into a reaction bottle, stirring to uniformly mix, adding a catalytic amount of silver oxide/potassium iodide catalyst, adding paratoluensulfonyl chloride with the same molar amount as the polyethylene glycol, stirring to react for 2-3 h at room temperature, and filtering and washing to obtain TsO-PEG-OH;
s2: dissolving TsO-PEG-OH in 25% ammonia water, adding equimolar ammonium chloride, stirring at 30 deg.C for 3 days, extracting with dichloromethane, and purifying the collected organic layer by column chromatography to obtain NH2-PEG-OH;
S3: the obtained NH2Dissolving PEG-OH in deionized water, adding equimolar amount of benzaldehyde-4-sodium sulfonate, adjusting pH to 6.5 to obtain a mixed solution, dropwise adding sodium aminoborohydride into the mixed solution, stirring and reacting at room temperature for 12 hours, and dialyzing, freezing and drying the reaction solution to obtain a solid; dissolving the solid in toluene, adding a polymerization inhibitor hydroquinone, a catalyst p-toluenesulfonic acid and monomer acrylic acid, heating to 110-120 ℃, stirring and refluxing for 4 hours, washing with a saturated sodium carbonate solution, separating liquid, performing rotary evaporation on an organic layer to remove the solvent, and recrystallizing to obtain the reactive anionic-nonionic monomer shown in the formula 1);
s4: adding pentaerythritol, triethylamine and anhydrous dioxane into a reaction bottle, introducing nitrogen to replace air in the reaction bottle, placing the reaction bottle in an environment at-18 ℃, dropwise adding a tetrahydrofuran solution of 2-bromoisobutyryl bromide in a nitrogen atmosphere, and after dropwise adding, moving the reaction bottle to room temperature to react for 12 hours under stirring; extracting with dichloromethane, collecting an organic layer, washing, drying, rotary steaming and recrystallizing to obtain an ATRP four-head initiator;
s5: sequentially adding a catalyst (a mixture of copper bromide and cuprous bromide), a coordination agent (bipyridyl bby), the ATRP four-head initiator and a reactive anion-nonionic monomer into a schlenk bottle, adding tetrahydrofuran, stirring to dissolve and mix the ATRP four-head initiator and the reactive anion-nonionic monomer uniformly, filling nitrogen into the schlenk bottle through three cycles of freezing, air extraction, thawing and air inflation, and reacting for 2-5 hours at 60 ℃; after the reaction is finished, adding tetrahydrofuran for dissolving and diluting, and then precipitating and separating out a polymer in a large amount of n-hexane after passing through neutral alumina, thus obtaining the anionic-nonionic dispersing agent.
The above preparation process can be expressed by the following equation, wherein n is the functionality of polyethylene glycol, preferably 5-15, i.e. the molecular weight of PEG is preferably between 200 and 800g/mol,
represents a polymer chain composed of reactive anionic-nonionic monomers. In the scheme, hydroxyl groups at two ends of polyethylene glycol are modified respectively, and the modification is carried out according to the following formula: 549-551 can synthesize high-selectivity amino-terminated polyethylene glycol NH
2PEG-OH reacts with benzaldehyde-4-sodium sulfonate to smoothly introduce sulfonic acid groups and imine groups, so that the anchoring effect is increased, and the compound has the anion-nonionic characteristic; at this time, the hydroxyl group at the other end is used to perform an esterification reaction with the carboxyl group of acrylic acid, and a terminal double bond is introduced to enable radical polymerization.
Pentaerythritol is used as a raw material to prepare a four-head ATRP initiator, the initiator is polymerized with the reactive anionic-nonionic monomer to obtain a multi-arm polymer, the steric hindrance between a molecular chain and the molecular chain is large, and the molecular weight of the polymer chain is not too large by regulating and controlling the polymerization degree, so that the possibility of molecular chain entanglement can be reduced, and the stability of the dispersing agent is improved; meanwhile, as the polymer has a plurality of molecular chains, the polymer can be ensured to have higher overall molecular weight and rich anchoring groups, thereby effectively improving the adsorption firmness and the dispersion performance. Meanwhile, the dispersing agent has nonionic characteristics of ether and anionic characteristics of sulfonate, and the application range of the dispersing medium is wide.
Example 1: PEG-200 is selected, and the feeding molar ratio of the catalyst, the coordination agent, the ATRP four-head initiator and the reactive anionic-nonionic monomer is 1:2:1: 100.
Example 2: PEG-400 is selected, and the feeding molar ratio of the catalyst, the coordination agent, the ATRP four-head initiator and the reactive anionic-nonionic monomer is 1:2:1: 80.
Example 3: PEG-800 is selected, and the feeding molar ratio of the catalyst, the coordination agent, the ATRP four-head initiator and the reactive anion-nonionic monomer is 1:2:1: 50.
Comparative example: the ATRP four-head initiator of example 1 was replaced directly with 2-bromoisobutyryl bromide as initiator, and the rest of the conditions were unchanged.
Measuring the critical micelle concentration CMC by using a surface tension meter; interfacial tensiometers measure surface tension. The test results are reported in table 1, with examples 1-3 having lower surface tensions and lower critical micelle concentrations.
TABLE 1
|
CMC(mol/L)
|
Surface tension (mN/m)
|
Example 1
|
1.1×10-3 |
27.5
|
Example 2
|
1.2×10-3 |
29.1
|
Example 3
|
1.1×10-3 |
28.3
|
Comparative example
|
3.2×10-3 |
36.8 |
Respectively taking inorganic matters and organic matters as dispersed particles, and preparing a dispersion liquid by using the prepared dispersing agent, wherein the dispersion liquid specifically comprises the following components:
application example 1: 0.2g of titanium dioxide is taken, 0.2g of the dispersing agent of the examples 1 to 3 and the comparative example of 10g of deionized water are respectively taken, mixed and stirred uniformly, and then ball-milled and dispersed for 40min to obtain titanium dioxide dispersion liquid which is respectively marked as products 1 to 4. After 30 days of standing, products 1-3 were observed to be homogeneous, with product 4 slightly agglomerated.
Application example 2: 1g of polyurethane emulsion is taken, 0.1g of the dispersant of the examples 1 to 3 and 10g of the deionized water of the comparative example are respectively taken to be mixed and stirred evenly by a machine, and the water-based polyurethane emulsion dispersion liquid is obtained and respectively marked as products 5 to 8. Products 5-8 are observed to be homogeneous after standing for 30 days, which shows that the dispersant has better dispersion stability for organic matters and inorganic fillers.
Application example 3: 1g of polyurethane emulsion is taken, 0.1g of the dispersant of the embodiment 1 and 10g of organic solvent (DMF or ethanol or ethyl acetate or diethanol amine) are mixed and stirred evenly by a machine, and aqueous polyurethane emulsion dispersion liquid is obtained and is respectively marked as products 9 to 12. After standing for 30 days, products 9-12 are observed to be homogeneous, namely the dispersant has a wide range of applicable solvent systems.
While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.