The synthesis and application of polyacrylamide resin began in the 1960s. In the past 30 years, the synthesis of polyacrylamide resins, functional modification and application research have never stopped. Due to the different synthesis methods of the cross-linking agent and the comonomer, therefore the polyacrylamide structure increses, and its application is more and more extensive.

Synthesis of polyacrylamide resin

Initially, the synthesis method of polyacrylamide resin is relatively rough. First, acrylamide and a crosslinking agent are dissolved in water, the polymerized into a bulk solid in an aqueous phase, and then crushed, and then polyacrylamide of different particle size is charged. There also have been attempting to suspend the oil-in-oil suspension polymerization method by dissolving the monomer and crosslinker in dimethyl sulfoxide or dimethyl terephthalate and suspending polymerization in another mutually incompatible oil phase. The more mature synthesis method is the water-in-oil reversed-phase suspension polymerization method. The monomer, initiator and crosslinker are dissolved in the aqueous phase and suspension polymerization is carried out in an incompatible organic phase.

Acrylamide is a water-soluble monomer. Some commonly used water-soluble comonomers are acrylic acid, fumaramide, N-generation acrylamide, styryltrimethylammonium chloride and the like. Morever, acrylonitrile, ethyl acrylate, vinyl acetate, or the like can also be used as the third monomer.

A commonly used crosslinking agent is a diene compound. Water-soluble is N, N'-methylenebisacrylamide, triethylene glycol diacrylate, oil-soluble divinylbenzene and halogenated alkylene oxide.

As the initiator, persulfate, hydrogen diisobutyronitrile, benzoyl peroxide can be used. In addition, it can also be initiated by heat or radiation.

A common aqueous phase is water or a mixture of water and ethanol. Commonly used oil phases are aliphatic hydrocarbons of 4-15 carbons. Instead of aliphatic hydrocarbons, aromatic hydrocarbons, kerosene, cyclohexane, etc., it may also be a mixture of several organic solutions. The synthesis reaction needs to be carried out under the protection of nitrogen.

The dispersing agent may be selected from salts, higher fatty acids, gelatin, high polymers, talc, diatomaceous earth, etc., and the most commonly used materials are class materials.

Polyacrylamide resins are synthesized in a variety of ways, often in different ways depending on the application. Sweden's Johansson and others have synthesized acrylamide - methacrylamide - NN'methylenebisacrylamide and acrylamide - NN'methylenebisacrylamide -1 -vinyl - 2 - pyrrolidone macroporous resin in two steps. They first made a solution of acrylamide, bisacrylamide and ammonium persulfate dissolved in water. Then, it was polymerized at 50 ° C for 1 hour in toluene with an existing dispersant. Additional monomer and crosslinker were added and polymerization was continued for 4 hours. A macroporous polyacrylamide resin is obtained.

A macroporous polyacrylamide resin can be obtained by subjecting macroporous polyacrylamide lipids to amine hydrolysis. Due to the difference in the amine hydrolysis reagent, a series of polyacrylamide resins containing different substituents can be obtained.

Further functionalization of the amide group

Third, the application of polyacrylamide resin

Due to the presence of an amide group in the polyacrylamide resin, it can form a hydrogen bond with many substances to cause adsorption. The amide group can also be further functionalized. Therefore, the application of the polyacrylamide resin is very extensive, and since the polyacrylamide resin can be made into microspheres and has good mechanical strength, it is particularly suitable as a chromatographic filler.

As a filler for size exclusion chromatography

Gel Permeation Chromatography Packing.

In 1981, the Japanese patent reported that acrylamide, propylene ester and NN'methylenebisacrylamide were copolymerized at 50-60 degrees for 2 hours. And ethanol-water was used as a solvent, and gasoline was a suspending agent. The obtained polyacrylamide resin was used for gel permeation chromatography with an exclusion limit of 2*105.

It has been reported in the literature that a large mesh polyacrylamide resin of about 10 microns can classify polyethylene oxide (PEO) and polyethylene glycol (PEG). The results show that the large mesh polyacrylamide resin has a high resolution in the lower capacity column and is much faster than the gel filtration classification. See picture 1.

High performance size exclusion chromatography (HPSEC)

When macroporous polyacrylamide resin is used in HPSEC, the polysaccharide and polyethylene oxide can be classified. The results show that the chromatographic filler has high resolution and separation ability for water-soluble high polymer and good separation effect on polysaccharide. Figure 2 is a chromatogram of the separation of glucose, sucrose and raffinose.

Reversed phase high performance liquid chromatography (HPLC)

The macroporous polyacrylamide resin is treated with a strong base to form a nucleophilic amide anion on the surface of the resin. The amide anion is reacted with n-18 alkyl bromide to form a C18 polyacrylamide resin. It can be used in HPLC to achieve similar effects to C18 silica gel, can be used in the range of PH1~13, and has long-term physical and chemical stability. For the retention and selectivity of aromatic compounds and polar organic solutions, it is similar to the silica gel column, and has better retention and selection for nitrogen-containing bases such as pyridine and aniline.

Biochemical applications

A polyacrylamide resin having a particle size of several hundred micrometers or less than one hundred of micrometers can be used for the gel column packing. It can effectively separate lactobacilli, white peony, 7-ball mites, crystal lumps, cytochrome globular proteins, and further desalinate and concentrate proteins. Polyacrylamide resins of different comonomers are selected depending on the protein to be separated.

Acrylamide and N,N'-(bisacrylamidemethyl)ethylene urea were dissolved in an aqueous solution of sodium acetate. Then, oxybenzene was used as a dispersion medium, and acetic acid and cellulose butyrate were used as a dispersing agent, and copolymerization was carried out at 60 degrees. The resulting resin can effectively separate a mixture of protein and enzyme. For example, the mixture of 1 mg of Blue Dextrun 2000 (molar amount 2,000,000), 15 mg of accompanying albumin (molar amount 87,000), 4 mg of ovalbumin (molar amount 468,000) and 7 mg of lysozyme (molar amount 14,600) was effectively separated.

Japanese patents have reported the copolymerization of acrylamide and sodium acrylate. The obtained cationic ruthenium resin can adsorb lysozyme up to 0.75g / g.

Polyacrylamide affinity chromatography and chromatography have been used to selectively separate rabbit antibodies, antiserum antibodies, and immunoglobulin mixtures, and the activity of the antibodies is not degraded.

Japanese patents have reported that the purification of urokinase with polyacrylamide resin as a chromatographic packing has a yield of up to 97%. The specific activity was 85,000 units/mg and there was no heat source and sediment.

In 1990, the Japanese patent reported the copolymerization of acrylamide and divinyl. The resulting polyacrylamide resin selectively adsorbs moisture and low molecular weight proteins from the protein mixture, and the remaining high molecular weight protein is concentrated. For example, they synthesize acrylamide-methylenebisacrylamide-diethylene glycol resin, which can be used to concentrate bovine serum albumin.