Reducing agent monomer for preparing styrene-acrylic emulsion by oxidation-reduction reaction at room temperature, and synthesis method thereof

Abstract

A reducing agent monomer for preparing a styrene-acrylic emulsion by an oxidation-reduction reaction at room temperature and a synthesis method thereof are disclosed. Maleic anhydride (MAH) and dimethylethanolamine (DMEA) are used as raw materials to synthesize the reducing agent monomer: 4-(2-(dimethylamino)ethoxy)-4-oxobut-2-enoic acid, and the synthesis method involves inexpensive easily-available raw materials, simple synthesis conditions, and easy purification. With the synthesized reducing agent monomer as a reducing agent, potassium persulfate (KPS) as an oxidizing agent, water as a dispersion medium, sodium dodecyl sulfate (SDS) as an emulsifier, and styrene, butyl acrylate (BA), and methylmethacrylate (MMA) as comonomers, free-radical microemulsion polymerization is conducted at room temperature to obtain a styrene-acrylic emulsion. In the synthesis of the styrene-acrylic emulsion, a monomer conversion rate is high, and a styrene-acrylic emulsion with a high molecular weight and a branched structure can be obtained at room temperature.

Claims

1. A method for preparing a styrene-acrylic emulsion by an oxidation-reduction reaction at room temperature using an oxidation-reduction initiation system, wherein the oxidation-reduction initiation system is formed from a reducing agent monomer and a persulfate, and the reducing agent monomer is 4-(2-(dimethylamino)ethoxy)-4-oxobut-2-enoic acid synthesized using maleic anhydride (MAH) and dimethylethanolamine (DMEA) as raw materials; the method comprises: adding a pH regulator, an emulsifier, the reducing agent monomer, and a dispersion medium into a reaction flask to obtain a mixture, and stirring said mixture for 3 min to 4 min to allow a thorough dissolution to obtain a mixed solution, wherein the dispersion medium is water (H.sub.2O); adding monomers into the mixed solution for pre-emulsification under stirring for 30 min to obtain a pre-emulsified product, wherein the monomers comprise styrene, butyl acrylate (BA), and methyl methacrylate (MMA); vacuum-pumping, and adding the persulfate to the pre-emulsified product in an argon atmosphere to obtain a resulting system; and subjecting the resulting system to a free-radical microemulsion polymerization in a thermostat water bath to obtain the styrene-acrylic emulsion.

2. The method according to claim 1, wherein a mass quantity ratio of the reducing agent monomer to persulfate is 1:(1-2); and the persulfate is ammonium persulfate (APS) or potassium persulfate (KPS).

3. The method according to claim 1, wherein the water is added at a mass of 1.5 times total mass of solids; and the styrene, the BA, and the MMA have a mass ratio of 1:1:0.25.

4. The method according to claim 1, wherein the emulsifier is sodium dodecyl sulfate (SDS), and the SDS is added at a mass 0.5% to 1% based on a total mass of the reducing agent monomer and the monomers styrene, butyl acrylate (BA), and methyl methacrylate (MMA).

5. The method according to claim 1, wherein the free-radical microemulsion polymerization is conducted at 25° C. for 8 h to 12 h.

6. The method according to claim 1, wherein the pH regulator is NaHCO.sub.3, and the NaHCO.sub.3 is added at a mass of 3% based on a total mass of the reducing agent monomer and the monomers styrene, butyl acrylate (BA), and methyl methacrylate (MMA).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a nuclear magnetic resonance (NMR) spectrum of the reducing agent monomer: 4-(2-(dimethylamino)ethoxy)-4-oxobut-2-enoic acid.

(2) FIG. 2 shows a differential molecular weight distribution curve of the polymer obtained in Example 4.

(3) FIG. 3 shows a differential molecular weight distribution curve of the polymer obtained in Example 5.

(4) FIG. 4 shows a differential molecular weight distribution curve of the polymer obtained in Example 6.

(5) FIG. 5 shows a Mark-Houwink curve of the polymer obtained in Example 4.

(6) FIG. 6 shows a Mark-Houwink curve of the polymer obtained in Example 5.

(7) FIG. 7 shows a Mark-Houwink curve of the polymer obtained in Example 6.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(8) The technical features of the present disclosure are further illustrated with the following examples, but a protection scope of the present disclosure is not limited to the following examples.

Example 1

(9) Synthesis of a Reducing Agent Monomer

(10) MAH (4.9 g, 0.05 mol) was added to a three-neck flask equipped with a thermometer, 30 mL of chloroform was added, and a resulting mixture was stirred at room temperature until the MAH was completely dissolved; DMEA (4.5 g, 0.05 mol) was dissolved in 10 mL of chloroform, and a resulting solution was added to the reaction flask all at once; a resulting system reacted at room temperature for 5 h to obtain a white suspension; 40 mL of diethyl ether was added, and a resulting mixture was thoroughly shaken and centrifuged to obtain a white solid; and the white solid was washed with 40 mL of diethyl ether, then suction filtration was conducted twice, and a resulting filter cake was vacuum-dried to a constant weight to obtain a white powder, with a total yield of 94.5%. An NMR spectrum of the product is shown in FIG. 1 of the specification.

Example 2

(11) Synthesis of a Reducing Agent Monomer

(12) MAH (4.9 g, 0.05 mol) was added to a three-neck flask equipped with a thermometer, 30 mL of chloroform was added, and a resulting mixture was stirred at room temperature until the MAH was completely dissolved; DMEA (2.3 g, 0.025 mol) was dissolved in 8 mL of chloroform, and a resulting solution was added to the reaction flask all at once; a resulting system reacted at room temperature for 4 h to obtain a white suspension; 40 mL of diethyl ether was added, and a resulting mixture was thoroughly shaken and centrifuged to obtain a white solid; and the white solid was washed with 40 mL of diethyl ether, then suction filtration was conducted twice, and a resulting filter cake was vacuum-dried to a constant weight to obtain a white powder, with a total yield of 65.7%.

Example 3

(13) Synthesis of a Reducing Agent Monomer

(14) MAH (4.9 g, 0.05 mol) was added to a three-neck flask equipped with a thermometer, 30 mL of chloroform was added, and a resulting mixture was stirred at room temperature until the MAH was completely dissolved; DMEA (9.0 g, 0.10 mol) was dissolved in 20 mL of chloroform, and a resulting solution was added to the reaction flask all at once; a resulting system reacted at room temperature for 8 h to obtain a white suspension; 40 mL of diethyl ether was added, and a resulting mixture was thoroughly shaken and centrifuged to obtain a white solid; and the white solid was washed with 40 mL of diethyl ether, then suction filtration was conducted twice, and a resulting filter cake was vacuum-dried to a constant weight to obtain a white powder, with a total yield of 57.7%.

Example 4

(15) Emulsion Polymerization NaHCO.sub.3 (0.0772 g, 3 wt % of total monomer), SDS (0.0117 g, 0.5 wt % of total monomer), the reducing agent monomer obtained in Example 1 (0.0187 g, 0.0001 mol), and H.sub.2O (4.2132 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0415 g, 0.01 mol), BA (1.2817 g, 0.01 mol), and MMA (0.2503 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and APS (0.0228 g, 0.0001 mol) was added at an argon atmosphere; and a resulting system reacted for 8 h in a 25° C. thermostat water bath to obtain the styrene-acrylic emulsion. As determined, a styrene conversion rate was 94%, a BA conversion rate was 94%, an MMA conversion rate was 96%, and a solid content was 59%. Then the emulsion was dropped into absolute methanol for demulsification, a resulting mixture was subjected to suction filtration with a Buchner funnel, and a resulting filter cake was dissolved in THF; and the absolute methanol precipitation was repeated three times to obtain a polymer M1. The polymer was analyzed by three-detection gel permeation chromatography (TG-GPC), and results were as follows: M.sub.n.SEC=4,120,000 g/mol, M.sub.w.SEC=30,090,000 g/mol, PDI=7.3, Mark-Houwink index α=0.568, and average branching factor g′=0.91. A differential molecular weight distribution curve of the obtained polymer M1 is shown in FIG. 2 of the specification; and a Mark-Houwink curve of the polymer M1 is shown in FIG. 5 of the specification.

Example 5

(16) Emulsion Polymerization

(17) NaHCO.sub.3 (0.0772 g, 3 wt % of total monomer), SDS (0.0119 g, 0.5 wt % of total monomer), the reducing agent monomer obtained in Example 1 (0.0561 g, 0.0003 mol), and H.sub.2O (4.3377 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0415 g, 0.01 mol), BA (1.2817 g, 0.01 mol), and MMA (0.2503 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and APS (0.0684 g, 0.0003 mol) was added at an argon atmosphere; and a resulting system reacted for 8 h in a 25° C. thermostat water bath to obtain the styrene-acrylic emulsion. As determined, a styrene conversion rate was 99%, a BA conversion rate was 99%, an MMA conversion rate was 92%, and a solid content was 59%. Then the emulsion was dropped into absolute methanol for demulsification, a resulting mixture was subjected to suction filtration with a Buchner funnel, and a resulting filter cake was dissolved in THF; and the absolute methanol precipitation was repeated three times to obtain a polymer M2. The polymer was analyzed by TG-GPC, and results were as follows: M.sub.n.SEC=2,310,000 g/mol, M.sub.w.SEC=17,800,000 g/mol, PDI=7.8, Mark-Houwink index α=0.521, and average branching factor g′=0.84. A differential molecular weight distribution curve of the obtained polymer M2 is shown in FIG. 3 of the specification; and a Mark-Houwink curve of the polymer M2 is shown in FIG. 6 of the specification.

Example 6

(18) Emulsion Polymerization

(19) NaHCO.sub.3 (0.0772 g, 3 wt % of total monomer), SDS (0.0121 g, 0.5 wt % of total monomer), the reducing agent monomer obtained in Example 1 (0.187 g, 0.001 mol), and H.sub.2O (4.7734 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0415 g, 0.01 mol), BA (1.2817 g, 0.01 mol), and MMA (0.2503 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and APS (0.228 g, 0.001 mol) was added at an argon atmosphere; and a resulting system reacted for 8 h in a 25° C. thermostat water bath to obtain the styrene-acrylic emulsion. As determined, a styrene conversion rate was 100%, a BA conversion rate was 97%, an MMA conversion rate was 96%, and a solid content was 59%. Then the emulsion was dropped into absolute methanol for demulsification, a resulting mixture was subjected to suction filtration with a Buchner funnel, and a resulting filter cake was dissolved in THF; and the absolute methanol precipitation was repeated three times to obtain a polymer M3. The polymer was analyzed by TG-GPC, and results were as follows: M.sub.n.SEC=1,880,000 g/mol, M.sub.w.SEC=18,900,000 g/mol, PDI=10.0, Mark-Houwink index α=0.408, and average branching factor g′=0.65. A differential molecular weight distribution curve of the obtained polymer M3 is shown in FIG. 4 of the specification; and a Mark-Houwink curve of the polymer M3 is shown in FIG. 7 of the specification.

Example 7

(20) Emulsion Polymerization

(21) NaHCO.sub.3 (0.0768 g, 3 wt % of total monomer), SDS (0.0023 g, 0.1 wt % of total monomer), the reducing agent monomer obtained in Example 1 (0.187 g, 0.001 mol), and H.sub.2O (4.7734 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0415 g, 0.01 mol), BA (1.2817 g, 0.01 mol), and MMA (0.2503 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and KPS (0.5411 g, 0.002 mol) was added at an argon atmosphere; and a resulting system reacted for 12 h in a 25° C. thermostat water bath to obtain the styrene-acrylic emulsion. As determined, a styrene conversion rate was 92%, a BA conversion rate was 86%, an MMA conversion rate was 90%, and a solid content was 57%. Then the emulsion was dropped into absolute methanol for demulsification, a resulting mixture was subjected to suction filtration with a Buchner funnel, and a resulting filter cake was dissolved in THF; and the absolute methanol precipitation was repeated three times to obtain a polymer. The polymer was analyzed by TG-GPC, and results were as follows: M.sub.n.SEC=2,070,000 g/mol, M.sub.w.SEC=22,200,000 g/mol, PDI=6.3, Mark-Houwink index α=0.608, and average branching factor g′=0.77.

Comparative Example 1

(22) NaHCO.sub.3 (0.0770 g, 3 wt % of total monomer), SDS (0.0021 g, 0.1 wt % of total monomer), and H.sub.2O (7.3060 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0420 g, 0.01 mol), BA (1.2812 g, 0.01 mol), and MMA (0.2510 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and an oxidizing agent of KPS (0.5413 g, 0.002 mol) and a reducing agent of dimethylaminoethyl methacrylate (DMAEMA) (0.3145 g, 0.002 mol) were added at an argon atmosphere; and a resulting system was placed in a 25° C. thermostat water bath, and no reaction occurred in the system.

Comparative Example 2

(23) NaHCO.sub.3 (0.0770 g, 3 wt % of total monomer), SDS (0.1040 g, 5 wt % of total monomer), and H.sub.2O (7.3060 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0420 g, 0.01 mol), BA (1.2812 g, 0.01 mol), and MMA (0.2510 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and an oxidizing agent of KPS (0.5413 g, 0.002 mol) and a reducing agent of DMAEMA (0.3145 g, 0.002 mol) were added at an argon atmosphere; a resulting system reacted for 12 h in a 25° C. thermostat water bath, and the system underwent agglomeration; and demulsification was conducted. As determined, a styrene conversion rate was 63%, a BA conversion rate was 55%, an MMA conversion rate was 60%, and a solid content was 30%. Then the emulsion was dropped into absolute methanol for demulsification, a resulting mixture was subjected to suction filtration with a Buchner funnel, and a resulting filter cake was dissolved in THF; and the absolute methanol precipitation was repeated three times to obtain a polymer. The polymer was analyzed by TG-GPC, and results were as follows: M.sub.n.SEC=207,800 g/mol, M.sub.w.SEC=898,000 g/mol, PDI=4.3, Mark-Houwink index α=0.7173, and average branching factor g′=0.98.

Comparative Example 3

(24) NaHCO.sub.3 (0.0768 g, 3 wt % of total monomer), SDS (0.1032 g, 5 wt % of total monomer), and H.sub.2O (7.3066 g, 60 wt % of emulsion) were weighed and added into a 50 mL reaction flask, and a resulting mixture was stirred for 3 min to 4 min to allow thorough dissolution; then styrene (1.0415 g, 0.01 mol), BA (1.2817 g, 0.01 mol), and MMA (0.2503 g, 0.0025 mol) were added, and pre-emulsification was conducted with stirring for about 30 min; vacuum-pumping was conducted, and an oxidizing agent of KPS (0.5411 g, 0.002 mol) and a reducing agent of sodium bisulfite (0.2609 g, 0.0025 mol) were added at an argon atmosphere; and a resulting system reacted for 24 h in a 25° C. thermostat water bath to obtain a styrene-acrylic emulsion. As determined, a styrene conversion rate was 89%, a BA conversion rate was 85%, an MMA conversion rate was 86%, and a solid content was 38%. Then the emulsion was dropped into absolute methanol for demulsification, a resulting mixture was subjected to suction filtration with a Buchner funnel, and a resulting filter cake was dissolved in THF; and the absolute methanol precipitation was repeated three times to obtain a polymer. The polymer was analyzed by TG-GPC, and results were as follows: M.sub.n.SEC=306,000 g/mol, M.sub.w.SEC=2,110,000 g/mol, PDI=6.9, Mark-Houwink index α=0.7896, and average branching factor g′=1.