A kind of H + / OH — Application of a switchable multifunctional monomer in emulsion polymerization

Abstract

The present invention discloses the application of an H + / OH — switch-type multifunctional monomer in emulsion polymerization, belonging to the fields of synthesis of multifunctional monomers and application of emulsion polymerization. The present invention synthesizes multifunctional monomers DMAMA and DMAIA. These monomers can exhibit different roles in different pH value systems. By using acid and base solutions with a certain concentration to adjust the H + / OH — content in the emulsion, it is found that at a specific pH value, it is both an emulsifier, a polymerization monomer, and a reducing agent. At this time, the emulsion system is stable, and free radical emulsion polymerization can be carried out at room temperature, and branched polymerization reaction occurs to obtain a high molecular weight polymer. When the H + concentration is less than OH — , the emulsion system is unstable, flocculation occurs, and the polymerization reaction terminates. Demulsification can be achieved without additional addition of a demulsifier. The present invention provides a new method for regulating the stability of the emulsion polymerization system and the preparation of functional polymers.

Description

Technical Field

[0001] The present invention belongs to the field of the design and preparation of multifunctional monomers in polymer chemistry and emulsion polymerization, and specifically relates to a reactive H + / OH — synthesis method of a switchable functional monomer and its application in room-temperature emulsion polymerization. Background Art

[0002] A reactive emulsifier is a monomer with emulsifying function and capable of participating in polymerization reactions. Traditional non-reactive emulsifiers mainly rely on physical adsorption to aggregate on the surface of latex particles. Therefore, when subjected to external forces, the adsorption of the emulsifier will be damaged, resulting in the instability of the emulsion. In contrast, reactive emulsifiers are bonded to the surface of latex particles in the form of covalent bonds and are not easily affected by external forces. Their reactivity can not only make the emulsion more stable, but also prevent the problem of emulsifier migration to the surface of the rubber film during the film-forming process of the emulsion, leading to performance degradation, and is suitable for the production and application of water-resistant coatings. According to their reactive groups, reactive emulsifiers can be classified into: allyl type, styrene type, acrylic type, acrylamide type, etc. According to the type of their hydrophilic groups, they can be classified into: anionic type, cationic type, and non-ionic type.

[0003] The hydrophilic group of cationic reactive emulsifiers is cationic, mostly quaternary ammonium salt type. The synthesis conditions of quaternary ammonium salt type emulsifiers are relatively complex, which are formed by the reaction of tertiary amines and alkyl halides under certain conditions. And when using it as an emulsifier, the polymerization reaction is difficult to carry out at room temperature. The structure of the tertiary amine before quaternization is a special structure with multiple functions. The inventor synthesized a polymerizable surfactant with reducibility in CN202010242562.2 A Polymerizable Surfactant with Reducibility and Its Preparation Method. When it is used in emulsion polymerization, sodium bicarbonate needs to be added. When it shows weak alkalinity, the polymerizable surfactant not only has excellent emulsifying properties, but also can participate in redox initiation reactions as a reducing agent. One-step emulsion polymerization can be carried out at normal temperature or low temperature to obtain an environmentally friendly emulsion with a branched structure. With the in-depth research of the inventor, it is found that the reducibility of its monomer is poor, and there is no research on how to achieve multifunctional transformation. An additional demulsifier needs to be added after the reaction to collect the polymer. And although it is well-known in the art that tertiary amine groups have reducibility, in practical applications, it is very difficult for emulsifiers containing tertiary amine groups to act as reducing agents, and their reducibility is very poor. And the emulsion obtained after polymerization is very stable, and an additional demulsifier needs to be added during demulsification.

[0004] In view of this problem, the present invention provides an H + / OH — switchable multifunctional monomer and its application in emulsion polymerization, by introducing acid and base solutions to adjust H + / OH —Content, at different pH values, regulates its conversion under various functions such as emulsifier, polymerization monomer, reducing agent, demulsifier, etc., providing a new idea for the controllability of emulsion polymerization. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to design and synthesize a kind of H + / OH — switchable multifunctional monomer and apply it to emulsion polymerization. By adjusting the concentration of H + and OH — in the functional monomer solution, it can exhibit different roles such as emulsifier, polymerization monomer, reducing agent, etc. in different pH value systems. It is both an emulsifier, a polymerization monomer, and a reducing agent at a specific pH value (5.0 ≤ pH value < 7.0). When it acts as a reducing agent and forms a redox initiation system with an oxidizing initiator, rapid initiation of polymerization can be achieved at room temperature (5 - 35 °C), and finally a high molecular weight polymer with a certain branched structure is obtained. In a stable polymer emulsion system, the reaction can be terminated directly by increasing the content of OH — in the emulsion without the need to add an additional demulsifier.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] Provide a kind of H + / OH — switchable multifunctional monomer, and its structural general formula:

[0008]

[0009] In the formula, R and R' are long-chain aliphatic hydrocarbon structures with different lengths.

[0010] Furthermore, the functional monomers are dimethylaminoethyl maleate 2-(tetradecyl ester) (DMAMA) and dimethylaminoethyl itaconate 2-(tetradecyl ester) (DMAIA), and their structural formulas are: DMAMA:

[0011]

[0012] DMAIA:

[0013]

[0014] H + / OH — The switchable multifunctional monomer can exhibit different functions in different pH value systems, and the specific applications are:

[0015] H + / OH —A switchable multifunctional monomer that, by adjusting its H + or OH — concentration in aqueous solution, exhibits different functions at different pH values: when the pH < 3.0, the functional monomer can only act as an emulsifier; when 3.0 ≤ pH < 5.0, the functional monomer can act as both an emulsifier and a monomer; when 5.0 ≤ pH < 7.0, the functional monomer can act as an emulsifier, a reducing agent, and a polymerizable monomer; when 7.0 ≤ pH < 8.0, the functional monomer acts only as a reducing agent and a polymerizable monomer; when the pH ≥ 8.0, the functional monomer acts only as a demulsifier; when the functional monomer acts as an emulsifier, its critical micelle concentration (CMC) is 0.0023 mol / L -1 -0.0035 mol / L -1 ; the room temperature is the environmental temperature in the laboratory, which is 5°C - 35°C.

[0016] Furthermore, different pH regulators are used to control the stability of the aqueous solution of the functional monomer. The functional monomer (DMAMA or DMAIA) is dissolved in deionized water containing a pH regulator at room temperature, and then a vinyl monomer is added and stirred to form a white emulsion. When the H + concentration in the emulsion is greater than the OH — concentration, H + can combine with the tertiary amine structure on the emulsifier monomer in the form of an ionic bond to form a stable emulsion. After adding an oxidant, the emulsion is stirred at room temperature, and blue light is generated in the system. After stirring for more than 4 hours, a high molecular weight polymer is obtained. By increasing the content of OH — in the stable polymer emulsion within the required reaction time, the polymerization reaction can be terminated, and the polymer directly precipitates; this functional monomer can also form a redox initiation system with an oxidizing initiator to achieve rapid initiation polymerization at room temperature, obtaining a high molecular weight polymer with a certain branched structure.

[0017] The specific emulsion polymerization process is as follows: Weigh the H + / OH — regulator and dissolve it in water, add the functional monomer and stir until it is dissolved to obtain a mixed solution. Control the pH value of the mixed solution by the amount of acid used, specifically 5.0 ≤ pH < 7.0. Add the vinyl monomer and stir to make it a homogeneous white emulsion. After pre-emulsification, stir in an ice bath, deoxygenate and purge with argon in the ice bath. After deoxygenation, add a persulfate oxidant under the condition of purging with argon. At this time, the emulsion is stable and there is blue light. After the room temperature emulsion polymerization reaction, adjust the pH ≥ 8.0 to terminate the emulsion polymerization reaction, and collect the polymer.

[0018] At room temperature, through emulsion polymerization, a hyperbranched polymer with ultra-high molecular weight is obtained. In a stable polymer emulsion system, the reaction can be terminated directly by increasing the content of OH in the emulsion (pH value ≥ 8.0), realizing the H / OH switch response of the emulsion. — The content of OH in the emulsion is flocculated (pH value ≥ 8.0) to terminate the reaction, achieving the H / OH + switch response of the emulsion. —

[0019] Furthermore, the H / OH regulator is hydrochloric acid, glacial acetic acid, sodium hydroxide, sodium bicarbonate, etc. + / OH —

[0020] In the preferred technical solution, the molar ratio of the functional monomer to H is 1:0.25 - 1.0; +

[0021] In the preferred technical solution, the molar ratio of the functional monomer to the vinyl monomer is 3 - 5:100;

[0022] In the preferred technical solution, the oxidant is persulfate, etc.;

[0023] In the preferred technical solution, the vinyl monomer is a vinyl monomer such as styrene, methacrylate, acrylic acid, etc.;

[0024] In the preferred technical solution, the molar ratio of the functional monomer to the oxidant is 5 - 10:1;

[0025] In the preferred technical solution, the room temperature of the emulsion polymerization is 5 - 35 °C;

[0026] In the preferred technical solution, the reaction time of the emulsion polymerization is 4 - 8 h;

[0027] In the preferred technical solution, when the emulsion polymerization system produces blue light, 3.0 < pH value < 7.0

[0028] In the preferred technical solution, the concentration of OH required to terminate the emulsion polymerization reaction is greater than the concentration of H; — The concentration of OH required to terminate the emulsion polymerization reaction is greater than the concentration of H; +

[0029] In the preferred technical solution, the pH value of the monomer as a reducing agent is controlled by the acid dosage to be 6.0 < pH value < 6.5;

[0030] Furthermore, H + ​​​​The addition (5.0 ≤ pH < 7.0) not only enhances the hydrophilicity of this functional monomer, but also improves the emulsifying ability to a certain extent. Under the condition of 5.0 ≤ pH < 7.0, it can also synergistically promote the reducibility, making the emulsion formed by this functional monomer have a lower particle size and better stability, and can initiate the polymerization reaction at room temperature or even at low temperature, with the characteristics of high conversion rate, high molecular weight and branched structure. The entire polymerization reaction has a simple system, is easy to operate, can be carried out at room temperature, saves energy consumption and cost, is environmentally friendly, and can be applied on a large scale to the production of functional polymers.

[0031] The advantages of the present invention are as follows:

[0032] 1. In the method of the present invention, the synthetic route of the reactive H + / OH — switchable emulsifier monomer is simple and has a high yield. When it is applied to emulsion polymerization, the emulsion polymerization can be regulated by adjusting the H + / OH — content, so that the emulsion remains stable and undergoes polymerization reaction under the condition of higher H + concentration, and flocculates and terminates the reaction under the condition of higher OH — concentration.

[0033] 2. The reactive H + / OH — switchable emulsifier monomer in the method of the present invention has a tertiary amine structure. When the molar ratio of this tertiary amine structure to H + is in the range of 1:0.25 to 1:1.0 (5.0 ≤ pH < 7.0), it can initiate the emulsion polymerization reaction with an oxidant at room temperature (5 - 35°C), and achieve the characteristics of high conversion rate and high molecular weight in a short time.

[0034] 3. The reactive H + / OH — switchable emulsifier monomer copolymerizes with the polymerization monomer and can be applied to the preparation of branched polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It shows the dissolution situation of the emulsifier monomer in water at different pH values in Example 1.

[0036] Figure 2 It shows the test situation of the emulsion stability at different pH values in Example 2.

[0037] Figure 3 It shows the emulsion situation under different H + / OH — contents.

[0038] Figure 4Effect of pH value on the conversion rate of styrene monomer in emulsion polymerization.

[0039] Figure 5 1H NMR spectrum of maleic acid 2-(tetradecyl)dimethylaminoethylamide (DMAMA). Specific implementation mode

[0040] Maleic acid 2-(tetradecyl)dimethylaminoethylamide (DMAMA)

[0041] Preparation method: Dissolve maleic anhydride (49.0302 g, 0.5 mol) in 300 mL of chloroform, add it to a three-necked flask equipped with a stirrer, reflux condenser and constant pressure dropping funnel, and after raising the temperature to 60 °C, add p-toluenesulfonic acid (0.1502 g, 0.3%) as a catalyst to the reaction vessel. Then dissolve N,N-dimethylethylenediamine (44.0110 g, 0.5 mol) in 100 mL of chloroform, slowly add it dropwise to the reaction vessel, stir and reflux for 2 h, cool the reaction mixture to room temperature for crystallization after the reaction, filter the precipitate by suction, recrystallize it twice with 200 mL of ethanol, and dry it under vacuum to constant weight to obtain a white powder. Dissolve the product of the previous step (90.8010 g, 0.5 mol) in chloroform and add myristyl alcohol (10.8401 g, 0.06 mol) to a three-necked flask, place it in an 80 °C water bath, and stir and react under reflux conditions for 24 h. After the reaction is completed, add anhydrous sodium sulfate to the chloroform solution for drying overnight, pass the chloroform solution through a basic alumina column, remove chloroform with a rotary evaporator at 30-40 °C, and dry it under vacuum to obtain the product. The purity measured by high performance liquid chromatography is 95.3%, and the 1H NMR spectrum is shown in the appendix Figure 5 .

[0042] Itaconic acid 2-(tetradecyl)dimethylaminoethylamide (DMAIA)

[0043] Preparation method: Dissolve itaconic anhydride (56.0101 g, 0.5 mol) in 300 mL of chloroform, add it to a three-necked flask equipped with a stirrer, reflux condenser and constant pressure dropping funnel. After heating to 60 °C, add p-toluenesulfonic acid (0.1505 g, 0.3%) as a catalyst to the reaction vessel. Then dissolve N,N-dimethylethylenediamine (44.0115 g, 0.5 mol) in 100 mL of chloroform, slowly add it dropwise to the reaction vessel, stir and reflux for 2 h. After the reaction, cool it to room temperature for crystallization, filter the precipitate by suction, recrystallize it twice with 200 mL of ethanol, and dry it under vacuum to constant weight to obtain a white powder. Dissolve the product of the previous step (100.0231 g, 0.5 mol) in chloroform and add myristyl alcohol (10.8407 g, 0.06 mol) to the three-necked flask, place it in an 80 °C water bath, stir and react under reflux conditions for 24 h. After the reaction, add anhydrous sodium sulfate to the chloroform solution for drying overnight, pass the chloroform solution through a basic alumina column, remove chloroform with a rotary evaporator at 30-40 °C, and dry it under vacuum to obtain the product. The purity measured by high performance liquid chromatography is 97.7%.

[0044] Example 1

[0045] Dissolution of emulsifier monomer in water at different pH values

[0046] Prepare 1 mol / L hydrochloric acid solution, glacial acetic acid solution and sodium hydroxide solution, and mix them in different proportions to prepare aqueous solutions with pH values ranging from 1 to 14. Weigh the functional monomer 2-(tetradecanoyl)oxyethyl dimethylamine maleate (DMAMA) (0.0410 g, 0.12 mmol) respectively and add it to 1.0 mL of aqueous solutions with different pH values, and dissolve it by ultrasonic dispersion to observe its dissolution.

[0047] As shown in the appendix Figure 1 As shown, as the pH value continuously increases, the solution becomes turbid. When the concentration of H + is greater than that of OH — (pH value < 7.0), DMAMA can be used as an emulsifier and can be completely dissolved in water. When the concentration of H + is less than or equal to that of OH — , the dissolution of the emulsifier is poor.

[0048] Example 2

[0049] Test of emulsion stability at different pH values

[0050] Prepare 1 mol / L hydrochloric acid solution, glacial acetic acid solution, and sodium hydroxide solution, and mix them in different proportions to prepare aqueous solutions with pH values ranging from 1 to 14. Weigh the functional monomer DMAMA (0.3402 g, 0.96 mmol) and add it to 8.0 mL of aqueous solutions with different pH values, and dissolve it by ultrasonic dispersion. After dissolution, weigh styrene (2.0011 g, 0.019 mol) and add it to the above-prepared DMAMA aqueous solutions respectively. After ultrasonic emulsification for 5 min, let it stand. Record the initial emulsion volume V0 and the remaining emulsion volume V after standing for 30 min, and calculate the emulsion stability coefficient V / V0. The higher the emulsion stability coefficient, the better the emulsifying ability of the emulsifier and the more stable the emulsion.

[0051] As shown in the appendix Figure 2 When the concentration of H + is greater than that of OH — (pH < 7.0), its emulsion stability is significantly better than that of the emulsion when the concentration of H + is less than that of OH — (pH ≥ 7.0). When 5 < pH < 7.0, the emulsion stability is better.

[0052] Example 3

[0053] Emulsion polymerization reaction

[0054] Weigh 37% dilute HCl (0.0953 g, 0.96 mmol) and dissolve it in deionized water (8.0021 g), and add the functional monomer DMAMA (0.3402 g, 0.96 mmol). After stirring until it dissolves, measure that the pH values of the mixed aqueous solution of the functional monomer and hydrochloric acid are 5.32 respectively. Weigh styrene (2.0032 g, 0.019 mol, m St :m water = 1:4) and add it. Stir at a speed of 800 r / min to make it a uniform white emulsion. After pre-emulsification for 30 min, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After deoxygenation is completed, add potassium persulfate (0.0263 g, 0.01 mmol) under the condition of purging with argon. Finally, tighten the bottle cap. In a 35°C constant temperature water bath, the emulsion is stable and has a blue light. After reacting for 4 h, the conversion rate of styrene monomer is measured to be 97.3%. The number average molecular weight M n of the obtained polymer is 442000 g / mol, the absolute weight average molecular weight M w.MALLS is 1220000 g / mol, and the branching factor g' is 0.88.

[0055] Example 4

[0056] Emulsion polymerization reaction

[0057] The study was carried out with the molar ratio of the functional monomer to dilute HCl with a concentration of 37% being 1:1, 1:0.75, 1:0.50, and 1:0.25. That is, HCl (0.0950 g, 0.96 mmol), (0.0711 g, 0.72 mmol), (0.0472 g, 0.48 mmol), (0.0241 g, 0.24 mmol) were weighed and dissolved in deionized water (8 g, 4 m St ) respectively, and the functional monomer DMAMA (0.3402 g, 0.96 mmol) was added. After stirring until it dissolved, the mixed aqueous solutions of the functional monomer and hydrochloric acid were denoted as M-HCl, M-0.75HCl, M-0.50HCl, and M-0.25HCl respectively. The corresponding pH values of the aqueous solutions were 5.34, 5.64, 6.12, and 6.49. Styrene (2.0000 g, 2.0002 g, 2.0002 g, 2.0001 g, 0.019 mol, m St :m water = 1:4) was added, and it was stirred at a speed of 800 r / min to form a uniform white emulsion. After pre-emulsifying for 30 min, it was stirred in an ice bath for 10 min, and deoxygenated and purged with argon in the ice bath, repeating 3 times. After deoxygenation was completed, potassium persulfate (0.0261 g, 0.0265 g, 0.0263 g, 0.0260 g, 0.01 mmol) was added under the state of purging with argon. Finally, the bottle stopper was tightened, and the reaction was carried out in a constant temperature water bath at 25 °C for 4 h respectively.

[0058] When the molar ratio of the functional monomer to HCl was 1:1 and 1:0.75, that is, when the pH values of M-HCl and M-0.75HCl were 5.34 and 5.64 respectively, the emulsion stability was good, as shown in the appendix Figure 3 shown. The corresponding monomer conversion rates were 95% and 97% respectively. The number-average molecular weights M n of the obtained polymers were 660000 g / mol and 560000 g / mol respectively, and the absolute weight-average molecular weights M w.MALLS were 2190000 g / mol and 1770000 g / mol respectively. The branching factors g’ were 0.88 and 0.86 respectively. When the molar ratio of the emulsifier to HCl was 1:0.50 and 1:0.25, that is, when the pH values of M-0.50HCl and M-0.25HCl were 6.12 and 6.49 respectively, the emulsion stability decreased. The monomer conversion rates were 87% and 80% respectively, as shown in the appendix Figure 4 shown. The number-average molecular weights M n were 630000 g / mol and 612000 g / mol respectively, and the absolute weight-average molecular weights M w.MALLSThey are 2350000 g / mol and 2880000 g / mol respectively, and the branching factors g' are 0.76 and 0.72 respectively. For M-HCl, M-0.75HCl, M-0.50HCl, and M-0.25HCl, the particle sizes of the polystyrene prepared by room-temperature emulsion polymerization are 27.2 nm, 30.0 nm, 30.8 nm, and 64.8 nm respectively. Their emulsion stabilities are M-HCl > M-0.75HCl > M-0.50HCl > M-0.25HCl, and the corresponding pH values gradually increase. When pH > 6.50, flocculation is likely to occur and the monomer conversion rate is relatively low. When the pH value < 6.50, the emulsion is stable and has a blue light (as shown in Figure 3 )

[0059] Example 5

[0060] Emulsion polymerization reaction

[0061] Weigh CH3COOH (0.0571 g, 0.96 mmol), (0.0433 g, 0.72 mmol), (0.0288 g, 0.48 mmol), and (0.0145 g, 0.24 mmol) respectively and dissolve them in deionized water (8 g, 4 m St ), and add the functional monomer DMAMA (0.3402 g, 0.96 mmol). After stirring until it dissolves, the pH values of the mixed aqueous solutions of the functional monomer and acetic acid are 5.76, 6.08, 6.32, and 6.50 respectively. Weigh styrene (2.0008 g, 2.0010 g, 2.0005 g, 2.0006 g, 0.019 mol, m St :m water = 1:4) respectively, and stir at a speed of 800 r / min to make it a uniform white emulsion, and pre-emulsify for 30 min. After pre-emulsification, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After deoxygenation is completed, add potassium persulfate (0.0521 g, 0.0522 g, 0.0520 g, 0.0525 g, 0.19 mmol) under the condition of purging with argon, and finally tighten the bottle cap and react in a 25°C constant temperature water bath for 8 h respectively.

[0062] When the molar ratio of the functional monomer DMAMA to CH3COOH is 1:1, 1:0.75, 1:0.50, and 1:0.25, the particle sizes of the polystyrene obtained by emulsion polymerization are 34.1 nm, 40.6 nm, 42.6 nm, and 72.3 nm respectively. When the molar ratio of the functional monomer DMAMA to CH3COOH is 1:1, the emulsion is stable and has a blue light (as shown in Figure 3As shown). When the molar ratio of DMAMA to CH3COOH is 1:1 and 1:0.75, the monomer conversion rates are 99.0% and 94.1% respectively, and the number-average molecular weight M n are 210000 g / mol and 170000 g / mol respectively, and the absolute weight-average molecular weight M w.MALLS are 2650000 g / mol and 1880000 g / mol respectively, and the branching factors g’ are 0.80 and 0.82 respectively. When the molar ratio of DMAMA to CH3COOH is 1:0.50 and 1:0.25, the emulsion stability decreases, and the monomer conversion rates are 83.4% and 76.1% respectively, and the number-average molecular weight M n are 193000 g / mol and 167000 g / mol respectively, and the absolute weight-average molecular weight M w.MALLS are 1550000 g / mol and 1520000 g / mol respectively, and the branching factors g’ are 0.87 and 0.85 respectively.

[0063] Example 6

[0064] Emulsion polymerization reaction

[0065] Weigh 37% dilute HCl (0.0951 g, 0.96 mmol), (0.0716 g, 0.72 mmol), (0.0471 g, 0.48 mmol) (0.0245 g, 0.24 mmol) respectively and dissolve them in deionized water (8 g, 4 m st ), and add H + / OH - Switchable itaconic acid 2-(tetradecanoyl)oxyethyl dimethylamine (DMAIA) (0.3505 g, 0.96 mmol). After it is dissolved, the measured pH values of the mixed aqueous solutions of DMAIA and HCl are 6.05, 6.16, 6.52, and 6.71 respectively. Weigh styrene (2.0002 g, 2.0003 g, 2.0001 g, 2.0003 g, 0.019 mol, m St :m water =1:4) respectively, stir at 800 r / min to make it a uniform white emulsion, and pre-emulsify for 30 min. After pre-emulsification, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath for 3 times. After deoxygenation is completed, add potassium persulfate (0.0260 g, 0.0263 g, 0.0261 g, 0.0264 g, 0.01 mmol) under the condition of purging with argon, and finally tighten the bottle cap, and react in a 25°C constant temperature water bath for 4 h respectively.

[0066] When the molar ratio of DMAIA to HCl is 1:1, 1:0.75, 1:0.50, and 1:0.25, the particle sizes of the polystyrene prepared by room-temperature emulsion polymerization are 42.2 nm, 44.7 nm, 48.3 nm, and 84.4 nm, respectively. When the molar ratio of the emulsifier to HCl is 1:1 and 1:0.75, the monomer conversion rates are 96.1% and 94.3%, respectively, and the number-average molecular weights M n are 480,000 g / mol and 220,000 g / mol, respectively, and the absolute weight-average molecular weights M w.MALLS are 630,000 g / mol and 550,000 g / mol, respectively, and the branching factors g’ are 0.78 and 0.80, respectively. When the molar ratio of DMAIA to HCl is 1:0.50 and 1:0.25, the emulsion stability decreases, and flocculation is likely to occur, and the monomer conversion rate decreases, being 79.1% and 53.0%, respectively, and the number-average molecular weights M n are 286,000 g / mol and 235,000 g / mol, respectively, and the absolute weight-average molecular weights M w.MALLS are 1,890,000 g / mol and 650,000 g / mol, respectively, and the branching factors g’ are 0.88 and 0.76, respectively.

[0067] Example 7

[0068] Emulsion polymerization reaction

[0069] Weigh CH3COOH (0.1151 g, 1.92 mmol), (0.0866 g, 1.44 mmol), (0.0577 g, 0.96 mmol) (0.0291 g, 0.48 mmol) and dissolve them in deionized water (8 g, 4 m st ), and add H + / OH - The switchable functional monomer DMAIA (0.7103 g, 1.92 mmol). Mix DMAIA and CH3COOH, and the corresponding pH values of their aqueous solutions are 6.01, 6.20, 6.61, and 6.75. Weigh styrene (2.0002 g, 2.0003 g, 2.0001 g, 2.0003 g, 0.019 mol, m St :m water = 1:4), and stir at 800 r / min to make it a uniform white emulsion, and pre-emulsify for 30 min. After pre-emulsification, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After deoxygenation is completed, add potassium persulfate (0.0521 g, 0.019 mmol) under the condition of purging with argon, and finally tighten the bottle cap and react in a 25°C constant temperature water bath for 4 h.

[0070] When the molar ratio of DMAIA to CH3COOH is 1:1, 1:0.75, 1:0.50, and 1:0.25, the corresponding particle sizes of polystyrene obtained by emulsion polymerization are 34.0 nm, 41.8 nm, 47.7 nm, and 69.9 nm, respectively. Among them, when the molar ratio of DMAIA to CH3COOH is 1:1 and 1:0.75, the monomer conversion rates are 96.2% and 91.1%, respectively, and the number-average molecular weight M n are 485000 g / mol and 362000 g / mol, respectively, and the absolute weight-average molecular weight M w.MALLS are 890000 g / mol and 630000 g / mol, respectively, and the branching factors g’ are 0.56 and 0.49, respectively. When the molar ratio of DMAIA to CH3COOH is 1:0.50 and 1:0.25, the emulsion stability decreases, the monomer conversion rates are 75.3% and 51.2%, respectively, and the number-average molecular weight M n are 333000 g / mol and 274000 g / mol, respectively, and the absolute weight-average molecular weight M w.MALLS are 1280000 g / mol and 1330000 g / mol, respectively, and the branching factors g’ are 0.47 and 0.50, respectively.

[0071] Example 8

[0072] Low-temperature emulsion polymerization reaction

[0073] Weigh CH3COOH (0.05701 g, 0.96 mmol) and dissolve it in deionized water (8.0010 g, 4 m st ), and add H + / OH - switch-type functional monomer DMAMA (0.3401 g, 0.96 mmol). After stirring until it is dissolved, the measured pH value of the solution is 6.03. Weigh styrene (2.0010 g, 0.019 mol), and stir it at 800 r / min to make it a uniform white emulsion, and pre-emulsify for 30 min. After pre-emulsification, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After deoxygenation is completed, add potassium persulfate (0.0521 g, 0.19 mmol) under the state of purging with argon, and finally tighten the bottle cap and react in a 10°C constant temperature water bath for 6 h. During the reaction process, the emulsion is stable and has a blue light, as shown in the appendix Figure 3 shown. The monomer conversion rate of styrene measured by gas chromatography is 95.74%, and the number-average molecular weight M n are 580000 g / mol, respectively, and the absolute weight-average molecular weight M w.MALLS are 2880000 g / mol, respectively, and the branching factors g’ are 0.79.

[0074] Example 9

[0075] Low-temperature emulsion polymerization reaction

[0076] Weigh CH3COOH (0.05700 g, 0.96 mmol) and dissolve it in deionized water (8.0004 g, 4 m st ) and add H + / OH - Switchable emulsifier monomer DMAIA (0.3503 g, 0.96 mmol). After stirring until it dissolves, the measured pH value of the solution is 6.03. Weigh styrene (2.0002 g, 0.019 mol), and stir it at a speed of 800 r / min to make it a uniform white emulsion. Pre-emulsify for 30 min. After the pre-emulsification is completed, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After deoxygenation is completed, add potassium persulfate (0.052 g, 0.019 mmol) under the condition of purging with argon, and finally tighten the bottle cap and react in a 5°C constant temperature water bath for 6 h. During the reaction process, the emulsion is stable and has a blue light. The monomer conversion rate of styrene measured by gas chromatography is 92.61%, and the number average molecular weight M n is 610,000 g / mol respectively, and the absolute weight average molecular weight M w.MALLS is 3,010,000 g / mol respectively, and the branching factor g’ is 0.81.

[0077] Example 10

[0078] Emulsion polymerization reaction

[0079] Weigh dilute HCl with a concentration of 37% (0.2180 g, 2.2 mmol) and dissolve it in deionized water (5.20 g, m 单体 :m 水 = 9:11) and add H + / OH -The switchable functional monomer DMAMA (0.7801 g, 2.2 mmol) was stirred until dissolved, and the corresponding pH values of the solution were measured to be 6.01. Acrylic acid (0.1100 g, 1.5 mmol), 2-hydroxyethyl acrylate (0.1000 g, 0.77 mmol), ethyl methacrylate (0.2202 g, 2.2 mmol), and isooctyl acrylate (4.0001 g, 0.02 mol) were weighed respectively and stirred at 800 r / min to form a homogeneous white emulsion, and pre-emulsified for 30 min. After pre-emulsification, it was stirred in an ice bath for 10 min, and deoxygenated and purged with argon in the ice bath, repeating 3 times. After deoxygenation, ammonium persulfate (0.0490 g, 0.21 mmol) was added under the condition of argon purging, and finally the bottle cap was tightened, and the reaction was carried out in a 25 °C constant temperature water bath for 8 h. During the reaction, the emulsion was stable and had a blue light, as shown in Figure 3 shown. The conversion rate of isooctyl acrylate measured by gas chromatography was 96.7%, the conversion rate of acrylic acid was 93.5%, the conversion rate of ethyl methacrylate was 95.3%, the conversion rate of 2-hydroxyethyl acrylate was 98.5%, and the number-average molecular weight M n was 145000 g / mol respectively, and the absolute weight-average molecular weight M w.MALLS was 431000 g / mol respectively, and the branching factor g' was 0.43.

[0080] Example 11

[0081] Emulsion polymerization reaction

[0082] 37% dilute HCl (0.1586 g, 1.6 mmol) was weighed and dissolved in deionized water (8.0002 g, 4 m n-BA ) and H + / OH - The switchable functional monomer DMAMA (0.5701 g, 1.6 mmol) was added. After stirring until dissolved, the pH value was measured to be 6.11. Butyl acrylate (2.0 g, 0.016 mol) was weighed and stirred at a certain speed to form a homogeneous white emulsion, and pre-emulsified for 30 min. After pre-emulsification, it was stirred in an ice bath for 10 min, and deoxygenated and purged with argon in the ice bath, repeating 3 times. After deoxygenation, the initiator potassium persulfate (0.042 g, 0.16 mmol) was added under the condition of argon purging, and finally the bottle cap was tightened, and the reaction was carried out in a 25 °C constant temperature water bath. During the reaction, the emulsion system was stable and had a blue light. After 8 h of reaction, the conversion rate of butyl acrylate was measured to be 89.1%. In the reaction emulsion system, 3 mL of NaOH solution (molar concentration of 1 mol / L) was added, and the emulsion was demulsified and the reaction stopped. At this time, the pH value of the system was 8.00. Further addition of NaOH solution caused the polymer to precipitate from the emulsion.

[0083] Comparative Example 1

[0084] Emulsion polymerization reaction

[0085] Weigh the functional monomer DMAMA (0.3402 g, 0.96 mmol) and add it to deionized water with pH = 7 (8 g, 4 m st ) and stir. After it dissolves, the pH of the solution is measured to be 7. Weigh styrene (2.0002 g, 0.019 mol), and stir it at a rotation speed of 800 r / min to make it into a uniform white emulsion, and pre-emulsify for 30 min. After the pre-emulsification is completed, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After the deoxygenation is completed, add potassium persulfate (0.0521 g, 0.19 mmol) under the state of purging with argon, and finally tighten the bottle cap and react in a 25°C constant temperature water bath for 8 h. During the reaction process, it is observed that the emulsion is unstable and flocculation occurs, as shown in Figure 3 . When there is no free H + in the emulsion, the emulsion is unstable. This functional monomer DMAMA only acts as a reducing agent and a polymerizable monomer, and cannot carry out a stable emulsion polymerization reaction without adding an emulsifier.

[0086] Comparative Example 2

[0087] Weigh the H + / OH - switchable functional monomer DMAMA (0.3411 g, 1 mmol) and dissolve it in deionized water with pH = 1.0 (8.0321 g, 4 m St ), and stir. After it dissolves, weigh styrene (St) (2.0121 g, 0.02 mol), and stir it at a rotation speed of 800 r / min to make it into a uniform white emulsion, and pre-emulsify for 30 min. After the pre-emulsification is completed, stir in an ice bath for 10 min, and deoxygenate and purge with argon in the ice bath, repeating 3 times. After the deoxygenation is completed, add potassium persulfate (0.0521 g, 0.2 mmol) under the state of purging with argon, and finally tighten the bottle cap and react in a 25°C constant temperature water bath for 6 h. The emulsion is stable, there is no blue light, and the system does not react. Under this condition, the functional monomer DMAMA is only used as a monomer.

[0088] Comparative Example 3

[0089] Weigh the H + / OH - switchable functional monomer DMAMA (0.3413 g, 1 mmol) and dissolve it in deionized water with pH = 3.0 (8.0325 g, 4 m St) After stirring until it dissolved, weigh styrene (St) (2.0121 g, 0.02 mol), and stir it at a speed of 800 r / min to make it into a uniform white emulsion, and pre-emulsify for 30 min. After the pre-emulsification is completed, stir it in an ice bath for 10 min, and deoxygenate and purge argon in the ice bath, repeating 3 times. After the deoxygenation is completed, add potassium persulfate (0.05212 g, 0.2 mmol) under the condition of purging argon, and finally tighten the bottle stopper, and react in a 25 °C constant temperature water bath for 6 h. The emulsion has a blue light, but the emulsion stability is not good. The conversion rate of styrene is 35.7%, and the number average molecular weight M n is 66000 g / mol respectively, and the absolute weight average molecular weight M w.MALLS is 1420000 g / mol respectively, and the branching factor g' is 1 respectively, forming polystyrene as a linear polymer. DMAMA has no reducibility in a system with a pH of 3.0 and can be used as an emulsifier and a monomer, but the emulsion stability is not good.

[0090] Comparative Example 4

[0091] Weigh H + / OH - The switchable functional monomer DMAMA (0.3411 g, 1 mmol) was dissolved in deionized water with a pH of 5.0 (8.0323 g, 4 m St ) After stirring until it dissolved, weigh styrene (St) (2.0120 g, 0.02 mol), and stir it at a speed of 800 r / min to make it into a uniform white emulsion, and pre-emulsify for 30 min. After the pre-emulsification is completed, stir it in an ice bath for 10 min, and deoxygenate and purge argon in the ice bath, repeating 3 times. After the deoxygenation is completed, add potassium persulfate (0.0520 g, 0.2 mmol) under the condition of purging argon, and finally tighten the bottle stopper, and react in a 25 °C constant temperature water bath for 6 h. The conversion rates of styrene are 92.1% in turn, and the number average molecular weight M n is 880000 g / mol respectively, and the absolute weight average molecular weight M w.MALLS is 2070000 g / mol respectively, and the branching factor g' is 0.96 respectively, forming polystyrene as a linear polymer. DMAMA has no reducibility in a system with a pH of 5.0 and only serves as an emulsifier and a monomer.

Claims

1. A kind of H + / OH — Application of a switchable multifunctional monomer in emulsion polymerization, characterized in that: 5.0 ≤ p The H value < 7.

0. The emulsion polymerization process of the multifunctional monomer is as follows: Weigh H + / OH — regulator and dissolve it in water. Add the multifunctional monomer. After stirring until it is dissolved, a mixed solution is obtained. Control the mixed solution to have a pH value of 5.0 ≤ p H value < 7.

0. Add the vinyl monomer and stir to make it into a homogeneous white emulsion. After deoxygenation, add the oxidant under the condition of argon gas passing to form a redox initiation system. At this time, the emulsion is stable and has a blue light. Carry out the emulsion polymerization reaction at room temperature. After the reaction, adjust the pH ≥ 8.0 Terminate the emulsion polymerization reaction, precipitate the polymer, and collect the polymer; The multifunctional monomer is maleic acid 2-(tetradecyl ester) dimethylaminoacetamide or / and itaconic acid 2-(tetradecyl ester) dimethylaminoacetamide; The structural formula of maleic acid 2-(tetradecyl ester) dimethylaminoacetamide is: ; The structural formula of itaconic acid 2-(tetradecyl ester) dimethylaminoacetamide is: 。 2. According to claim 1, H + / OH — Application of a switchable multifunctional monomer in emulsion polymerization, characterized in that: H + / OH — The regulator is one of hydrochloric acid, glacial acetic acid, sodium hydroxide, and sodium bicarbonate.

3. According to claim 1, H + / OH — Application of a switchable multifunctional monomer in emulsion polymerization, characterized in that: Multifunctional monomer: H + / OH — The molar ratio of the regulator is 1:0.25 to 1.

0.

4. According to claim 1, H + / OH — The application of a switchable multifunctional monomer in emulsion polymerization, characterized in that: The molar ratio of the multifunctional monomer to the vinyl monomer is 3-5:

100.

5. According to claim 1, H + / OH — Application of a switchable multifunctional monomer in emulsion polymerization, characterized in that: The vinyl monomer is styrene, methacrylate, or acrylic monomer.

6. H according to claim 1 + / OH — The application of switchable multifunctional monomer in emulsion polymerization is characterized by: The oxidizing agent is persulfate.

7. H according to claim 1 + / OH — The application of switchable multifunctional monomer in emulsion polymerization is characterized by: The molar ratio of the multifunctional monomer to the oxidizing agent is 5-10:

1.

8. According to claim 1, H + / OH — The application of a switchable multifunctional monomer in emulsion polymerization, characterized in that: The polymerization reaction time is 4-8 h; the polymerization reaction is carried out at room temperature, and the room temperature is 5°C-35°C.

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