CN110229270B

CN110229270B - Preparation of salt-resistant amphoteric polyacrylamide by using transition metal salt to catalyze persulfate-tertiary amine redox to initiate free radical polymerization

Info

Publication number: CN110229270B
Application number: CN201910481098.XA
Authority: CN
Inventors: 李丁; 向俊; 吴雨辰
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2019-06-04
Filing date: 2019-06-04
Publication date: 2021-06-01
Anticipated expiration: 2039-06-04
Also published as: CN110229270A

Abstract

The invention belongs to the field of preparation of high molecular weight polymers, and relates to a method for preparing high molecular weight amphoteric polyacrylamide by copolymerization of acrylamide and sulfobetaine monomers. The reaction process of the invention is that FeII/polycarboxylic acid or CuII/polybasic tertiary amine complex ion is used to catalyze sodium persulfate and water-soluble aliphatic tertiary amine to form an oxidation-reduction initiation system, and acrylamide and methacrylate sulfonic acid betaine monomer are initiated to carry out free radical copolymerization at low temperature in aqueous solution containing a small amount of cationic monomer. The invention has the advantages that: the raw materials are cheap and easy to purchase and are stable to moisture in air. Because the polymerization starting temperature is lower, the heat dissipation is stably carried out, the polymerization process is mild, and no sudden polymerization or crosslinking occurs, the obtained amphoteric polyacrylamide has good solubility and higher molecular weight.

Description

Preparation of salt-resistant amphoteric polyacrylamide by using transition metal salt to catalyze persulfate-tertiary amine redox to initiate free radical polymerization

Technical Field

The invention belongs to the field of preparation of high molecular weight polymers, relates to free radical polymerization of acrylamide (AAm), and particularly relates to a method for catalyzing free radical copolymerization of AAm and methacrylate sulfonate betaine monomers by using an iron or copper salt complex in an aqueous solution containing a small amount of peroxide, water-soluble aliphatic tertiary amine and cationic monomers, wherein the polymerization speed is regulated to form the high molecular weight polymers at a higher polymerization speed and avoid forming crosslinked insoluble substances through sudden polymerization, so that amphoteric polyacrylamide with good water solubility and high salt resistance is obtained.

Background

Acrylamide homo/copolymers (PAAm) polymerized by using acrylamide (AAm) as a main monomer are widely applied to industries such as water treatment and the like. Whether it is a homopolymeric PAAm or a copolymeric PAAm obtained from a monomer that is the same as AAm, either cationic (e.g., methacryloyloxyethyltrimethylammonium chloride (DMC) or anionic (e.g., sodium acrylate NaAAc)), because the polymer chain mainly contains a charge, it exhibits polyelectrolyte properties after being dissolved in aqueous solution, such as a substantial drop in viscosity in saline solution, and even a direct precipitation (Fangdao, Guofiwei, Haruanhua acrylamide polymers, chemical industry publishers, 2006). To overcome the sensitivity of PAAm to brine, the strategy currently adopted is to perform ternary polymerization of AAm with cationic monomers and anionic monomers. For example, Xilong et al invented a method for preparing amphoteric PAAm by emulsion polymerization, and obtained amphoteric PAAm (Xilong, Lixia, Lilisishan, a preparation method of amphoteric polyacrylamide, grant No. CN 104558405B) by ternary copolymerization of AAm, DMC and 2-acrylamide-2-methyl propyl sodium sulfonate (AMPS). Other methods of preparing amphoteric polyacrylamides are generally similar, except that the cationic monomers are selected differently from the anionic monomers. Such methods require controlling the molar feed ratio of cationic monomer to anionic monomer to be around 1:1, otherwise the polyelectrolyte effect in the aqueous salt solution remains difficult to overcome.

The Qianjiao uses AAm and 4-vinyl pyridine sulfonic acid betaine monomer to carry out free radical copolymerization, thereby obtaining amphoteric PAAm (preparation method of Qianjiao, Guizhang, safe neutral zwitterionic polyacrylamide flocculant, publication No. CN 101412785A). The sulfobetaine monomer contains both anions (typically carboxylic acid, sulfonate) and cations (typically quaternary ammonium salt, pyridinium salt structures) covalently linked together, and thus the anionic moiety in the amphoteric PAAm chain obtained after AAm copolymerization: the cation ratio was also fixed to about 1: 1. Such copolymer PAAm also exhibits high salt resistance and superior flocculation in high salinity aqueous solutions. However, the intrinsic viscosity of the polymer obtained by the method in aqueous solution is lower and is only 100-600mL/g, which indicates that the molecular weight of the obtained polymer is lower. Similarly, the molecular weight of amphoteric PAAms obtained by conventional free radical copolymerization of AAm with other zwitterionic monomers is also generally low (Tao Ye, Yihu Song, Qiang Zheng Salt response and rhelogical behavor of acrylamide-sulfobetaine copolymer Colloid Sci (2016)294: 389-397-; Tao Ye, Yihu Song, Qiang Zhung Synthesis and solubility property of acrylamide-sulfobetaine copolymer Colloid Sci (2015)293: 797-807).

We have proposed in earlier patent applications that iron salt complexes are often inexpensively stabilized in the presence of free halogen or pseudohalogen ions (e.g., Cl)^-、Br^-Or^-SC(＝S)N(C₂H₅)₂) In the aqueous solution of (1), small molecular aliphatic tertiary amine is oxidized to initiate free radical polymerization of AAm (Dianzhi group, aqueous solution reverse atom transfer free radical polymerization of Chenqi acrylamide, publication No. CN 109251261A). The method can obtain viscosity average molecular weight of 10⁶-10⁷High molecular weight homo-polymeric PAAm. The common cheap and stable copper or iron salt complex is used for catalyzing persulfate-micromolecule aliphatic tertiary amine to form an oxidation-reduction system containing free halogen ions (such as chloride ions or ferric salt)Bromide ion) in an aqueous solution (CHENQI, SUISHANG, ZHANYONG, preparation of a biopolymer acrylamide copolymer by radical polymerization of a Zhai photophobic group, publication No. CN108641035A), a viscosity average molecular weight of more than 10 can be obtained⁷The nonionic PAAm of (a). In the invention, the persulfate-DMAEMA is used for constituting a redox initiation system, because the DMAEMA contains polymerizable double bonds, part of polymer chains generated by initiation can be further polymerized; on the other hand, free bromide ions added in the form of NaBr in the solution and the copper or iron salt complex form a complex containing halogen ligands in situ, and the propagating radicals are passivated to form carbon-bromine covalent bonds and reduced to be cuprous or ferrous salt complexes. After the persulfate is completely consumed, the cuprous or ferrous salt complex catalyzes a polymer chain with a carbon-bromine covalent bond at the tail end to continuously initiate the polymerization of the residual monomers by an atom transfer radical polymerization mechanism. Since the copper or iron salt complex containing the halogen ligand can continuously passivate the growing free radicals, the instantaneous concentration of the free radicals is low, thereby reducing the polymerization speed. Finally, not only can the polymerization reaction exotherm be controlled, but macroscopic gel formation due to extensive crosslinking is also avoided. However, in this system, most of the added NaBr remains in the polymerization system, and the system is not suitable for preparing amphoteric PAAm because the viscosity of the system after polymerization is very high and the removal is impossible.

In the invention, common cheap and stable iron salt complex is used for catalyzing persulfate-micromolecule aliphatic tertiary amine in aqueous solution containing a small amount of cationic monomer to initiate copolymerization of AAm and methacrylate sulfonate betaine monomer. Cationic monomers contain polymerizable double bonds and halide ions, and such monomers become part of the polymer chain after polymerization. Therefore, the cationic monomer is used as a halogen source instead of the free inorganic halide, and almost no free halogen ion exists in the reaction solution after the polymerization. The obtained amphoteric PAAm has higher intrinsic viscosity number in aqueous solution, generally about 600-2500mL/g, which is significantly higher than the molecular weight of amphoteric PAAm obtained by other methods.

Disclosure of Invention

The reaction process of the invention is to use Fe^IIDisodium Ethylenediaminetetraacetate (EDTA) orCu^IITris (2-N, N-dimethylamino) ethylamine (Me)₆TREN) complex ion catalyzes sodium persulfate (NaPS) and water-soluble aliphatic tertiary amine (such as N, N-Diethylaminoethanol (DEAE), Triethanolamine (TEOA), and 2- (N, N-dimethylamino) ethyl methacrylate (DMAEMA) to form a redox initiation system, and initiates free radical polymerization of AAm and N, N-dimethyl (methacryloyloxyethyl) ammonio propanesulfonate (DMAPS) in an aqueous solution containing a small amount of cationic monomer (methacryloyloxyethyl trimethyl ammonium chloride (DMC) or dimethyldiallyl ammonium chloride (DADMAC)). The invention has the advantages that: the invention has simple operation, low external requirement, cheap and easily purchased raw materials, stable moisture in air, stable polymerization, no sudden polymerization or crosslinking, good water solubility of the obtained amphoteric PAAm, high intrinsic viscosity and large molecular weight. The polymerization system has no free halogen ions.

The technical scheme adopted by the invention comprises the following specific operation steps:

(1) preparing a reaction solution

According to different reaction conditions, a certain amount of reagents (catalyst mother liquor, water-soluble aliphatic tertiary amine, cationic monomer aqueous solution mother liquor, AAm aqueous solution mother liquor, DMAPS dry powder and NaPS aqueous solution mother liquor) of each component are weighed and added into a plastic self-sealing bag in batches, deionized water is added to adjust the total volume to be 100mL, and the components are stirred to be uniformly mixed.

(2) Reaction takes place

And introducing argon into the prepared reaction liquid to remove oxygen for a certain time, and sealing the reaction liquid and then starting the reaction in a water bath at a certain temperature.

(3) Polymer separation

After the polymerization is finished, dissolving the obtained polymer by using water, precipitating and separating out the polymer by using ethanol, and placing the separated molecular weight sample in an oven for drying.

(4) Testing

The viscosity-average molecular weight of the polymer is measured by a viscosity method. The molecular weight of the obtained copolymer sample is measured by a single-point viscosity method, and the method comprises the following specific steps: weighing 0.50-0.70g L^-1Dissolving the dried polymer in deionized water to prepare 100mL of polymer aqueous solution, and heating in water bath at 30 DEG CThe flow-out times of the deionized water and the polymer solution were measured at this temperature using an Ubbelohde viscometer, respectively.

(5) Computing

The intrinsic viscosity ([ eta ]) of the polymer was calculated according to the following formula:

the polymer viscosity average molecular weight was then calculated from the Mark-Houwink equation as follows:

[η]＝kM_ν ^α (2)

wherein k is 0.00631mL g^-1，α＝0.8(M.Kurata,X Tsunashima,Viscosity-molecular weight relationships and unperturbed dimensions of linear chain molecules,in Polymer Handbook,4^th Edition；Eds.:J.Brandrup,E.H.Immergut,E.A.Grulke；Wiley,Pergamon,2003；VII/10)。

Detailed Description

The present invention will be further described in detail with reference to the following examples. The following examples are illustrative of the preferred embodiments of the present invention, but the present invention is not limited to the following examples, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.

Example 1:

a total volume of 100mL of aqueous solution was prepared, wherein the initial concentration of AAm (noted as [ AAm ]]₀) Is 4.9mol L^-1DMAEMA starting concentration (noted as [ DMAEMA ]]₀) Is 18mmol L^-1DMC onset concentration (noted as [ DMC ]]₀) Was 14.1mmol L^-1、FeCl₂EDTA initial concentration (noted as [ Fe ]^II/EDTA]₀Wherein [ Fe ]^II]₀:[EDTA]₀Is fixed at an equivalent ratio of 1:1) of 11.0. mu. mol L^-1Initial concentration of DMAPS (noted as [ DMAPS ]]₀) Is 31mmol L^-1. Mixing AAm, DMAEMA, DMC and FeCl₂Adding EDTA and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the initial concentration of NaPS (marked as [ NaPS ] is obtained]₀) 0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm 7.56 × 10 determined by viscosity method⁶。

Example 2:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.9mol L^-1、[DMAEMA]₀Is 18mmol L^-1、[DMC]₀Was 14.1mmol L^-1、[Fe^II/EDTA]₀11.0. mu. mol L^-1、[DMAPS]₀Is 62mmol L^-1. Mixing AAm, DMAEMA, DMC and FeCl₂Adding EDTA and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the [ NaPS ] is dissolved]₀0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 3.41 × 10⁶。

Example 3:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.9mol L^-1、[DMAEMA]₀Is 18mmol L^-1、[DMC]₀Was 14.1mmol L^-1、[Fe^II/EDTA]₀11.0. mu. mol L^-1、[DMAPS]₀Is 93mmol L^-1. Mixing AAm, DMAEMA, DMC and FeCl₂/EDAdding TA and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the [ NaPS ] is dissolved in the solution]₀0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 1.69 × 10⁶。

Example 4:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.9mol L^-1、[DMAEMA]₀Is 18mmol L^-1、[DMC]₀Was 14.1mmol L^-1、[Fe^II/EDTA]₀11.0. mu. mol L^-1、[DMAPS]₀Is 124mmol L^-1. Mixing AAm, DMAEMA, DMC and FeCl₂Adding EDTA and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the [ NaPS ] is dissolved]₀0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 2.31 × 10⁶。

Example 5:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.9mol L^-1Initial concentration of TEOA (noted as [ TEOA)]₀) Is 22mmol L^-1、[DMC]₀ 14.1mmol L^-1、[Fe^II/EDTA]₀11.0. mu. mol L^-1、[DMAPS]₀Is 31mmol L^-1. Mixing AAm, TEOA, DMC, FeCl₂EDTA, DMAPS driedAdding the powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding the mixture into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the [ NaPS ] is]₀0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 2.60 × 10⁶。

Example 6:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.8mol L^-1DEAE initial concentration (note as [ DEAE)]₀) Is 22mmol L^-1、[DMC]₀Is 14.0mmol L^-1、[Fe^II/EDTA]₀11.0. mu. mol L^-1、[DMAPS]₀Is 31mmol L^-1. Mixing AAm, DEAE, DMC, FeCl₂Adding EDTA and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the [ NaPS ] is dissolved]₀1.55mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 4.61 × 10⁶。

Example 7:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.9mol L^-1、[DMAEMA]₀Is 18mmol L^-1、[DMC]₀Was 14.1mmol L^-1、CuSO₄·5H₂O/Me₆Starting concentration of TREN (noted as [ Cu ]^II/Me₆TREN]₀In which [ Cu ]^II]₀:[Me₆TREN]₀Is fixed at an equivalent ratio of 1:1) of 11.0. mu. mol L^-1，[DMAPS]₀Is 31mmol L^-1. Mixing AAm, DMAEMA, DMC, CuSO₄·H₂O/Me₆Adding TREN and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that [ NaPS ] is obtained]₀0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 4.33 × 10⁶。

Example 8:

preparing an aqueous solution having a total volume of 100mL, wherein [ AAm]₀Is 4.9mol L^-1、[DMAEMA]₀Is 18mmol L^-1Starting concentration of DMDAAC (noted as [ DMDAAC ]]₀) 10.9mmol L^-1、[Fe^II/EDTA]₀11.0. mu. mol L^-1、[DMAPS]₀Is 31mmol L^-1. Mixing AAm, DMAEMA, DMDAAC and FeCl₂Adding EDTA and DMAPS dry powder into a beaker, stirring until the DMAPS dry powder is completely dissolved, uniformly mixing, adding into a plastic self-sealing bag, introducing argon to remove oxygen for 15min, and adding NaPS into the plastic self-sealing bag to ensure that the [ NaPS ] is dissolved]₀0.78mmol L^-1And after continuously deoxidizing for 15min, extruding to remove residual air in the self-sealing bag, and sealing. Then reacting in water bath at 20 ℃, the viscosity of the reaction solution gradually rises, the temperature continuously rises, and the temperature of the reaction solution is kept stable for a short time and then gradually falls after the monomers are completely converted. And after the temperature of the reaction micelle is reduced to normal temperature after 6 hours, taking out the polymer to be tested. PAAm obtained by measuring viscosity is 4.85 × 10⁶。

Claims

1. A process for the preparation of high molecular weight amphoteric polyacrylamide (PAAm), characterized in that: catalyzing persulfate-micromolecule aliphatic tertiary amine in aqueous solution containing a cationic monomer by using a transition metal salt complex catalyst to initiate acrylamide (AAm) and a sulfobetaine monomer to carry out free radical copolymerization to obtain high-molecular-weight amphoteric PAAm;

(1) the transition metal salt complex catalyst comprises ferrous salt (marked as Fe)^II) With disodium Edetate (EDTANA)₂) The complex formed (noted as Fe)^II/EDTANa₂) And salts of copper in a high oxidation state (denoted as Cu)^II) Complex with tris (2-N, N-dimethylamino) ethylamine (denoted as Cu)^II/Me₆TREN)；

(2) The micromolecular aliphatic tertiary amine comprises N, N-diethylaminoethanol, triethanolamine and 2- (N, N-dimethylamino) ethyl methacrylate;

(3) the sulfobetaine monomer is N, N-dimethyl (methacryloyloxyethyl) ammonio propanesulfonic acid inner salt, namely DMAPS;

(4) the cationic monomer comprises methacryloyloxyethyl trimethyl ammonium chloride (DMC); and dimethyldiallylammonium chloride, DADMAC.

2. The method of claim 1, wherein the AAm initial concentration is in the range of 3.8 to 3.9mol L^-1。

3. The method according to claim 1, wherein the concentration of the transition metal salt complex catalyst is in the range of 11.0-1200 μmol L^-1。

4. The method of claim 1, wherein the concentration of the small-molecule aliphatic tertiary amine ranges from 18.0 mmol L to 22.0mmol L^-1。

5. The method of claim 1, wherein the DMAPS concentration is in the range of 30.0-130.0mmol L^-1。

6. The method of claim 1, wherein the concentration of said cationic monomer is in the range of 10.0 to 14.0mmol L^-1。

7. The high molecular weight amphoteric polyacrylamide (PAAm) obtained by the method according to claim 1, wherein the intrinsic viscosity of the high molecular weight amphoteric polyacrylamide (PAAm) in aqueous solution is in the range of 600-2000mL/g, and the corresponding viscosity-average molecular weight is in the range of 1.8 x 10⁶-1.30×10⁷。