Dendrimer-based scale inhibitor and use thereof

Abstract

The application discloses a dendrimer-based scale inhibitor and application thereof. The scale inhibitor is prepared from dendrimers and water; the dendrimers are polyamide-amine PAMAM series dendrimers with alkyl diamine as a core. The application fully studies the influence of scale inhibitor types, scale inhibitor concentrations and system temperatures on the performance of the scale inhibitor, and compares the scale inhibitor with commercial products under optimal conditions. The results show that the PAMAM scale inhibitor with a specific structure can effectively reduce the pollution or damage caused by silicate scale and calcium sulfate scale in industrial water, and is significantly superior to commercial products in the performance of resisting silicate scale.

Description

Technical Field

[0001] This invention belongs to the field of water treatment chemicals, specifically relating to a scale inhibitor based on dendritic macromolecules and its application. Background Technology

[0002] In industrial water treatment systems, the calcium in the water... 2+ Mg 2+ Easy to CO3 2- SO4 2- SiO3 2- PO4 3- Scale forms and deposits on the metal surfaces inside pipes and equipment, causing blockages, increased energy consumption, reduced productivity, and ultimately higher operating costs. Silica and calcium sulfate scale are particularly difficult to remove. Scale inhibitors, especially those containing phosphonates and polyphosphates, can effectively prevent the formation of various types of scale. However, these scale inhibitors can cause environmental problems; therefore, the research and development of environmentally friendly scale inhibitors has great potential for application.

[0003] Dendritic macromolecules are a new type of polymer with a three-dimensional structure, high branching, and high order. During synthesis, their size, shape, structure, and functional groups can be strictly controlled at the molecular level. The products are generally highly symmetrical and monodisperse. The internal cavities, surface functional groups, and highly branched structures of the molecules exhibit chelating and encapsulation effects, making them promising for applications in host-guest chemistry, demulsification and solubilization, and catalysts.

[0004] In response to the demand for environmentally friendly scale inhibitors and taking into account the characteristics of dendritic macromolecules, a scale inhibitor based on polyamide-amine (PAMAM) dendritic macromolecules with abundant amino groups at the end groups is proposed to overcome the shortcomings of current scale inhibitors, such as low scale inhibition rate and short lifespan. Summary of the Invention

[0005] Purpose of the Invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a scale inhibitor based on dendritic macromolecules and its applications. The scale inhibitor of this invention is a high-performance, phosphorus-free scale inhibitor for calcium silicate and calcium sulfate in water. It exhibits a high scale inhibition rate and is suitable for inhibiting silica and calcium sulfate scale in industrial water, thereby extending the operating cycle and lifespan of the system.

[0006] Technical solution: The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a scale inhibitor based on dendritic macromolecules, which is prepared by dendritic macromolecules and water; the dendritic macromolecules are polyamide-amine PAMAM series dendritic macromolecules with alkyl diamine cores.

[0008] The scale inhibitor of this invention is a PAMAM dendritic macromolecular scale inhibitor based on a specific alkyl diamine core. The dendritic macromolecule with its specific structure possesses characteristics such as being environmentally friendly, temperature resistant, and compatible. In particular, the number of functional groups and the properties of its end groups can effectively inhibit the growth of silica scale in high-silica cooling water.

[0009] Preferably, the core molecule of the polyamide-amine PAMAM series dendritic macromolecule is one of ethylenediamine, propylenediamine, butylenediamine, or hexamethylenediamine.

[0010] Preferably, the generation of the polyamide-amine PAMAM series dendritic macromolecules is one of 0.5G, 1G, 1.5G or 2G.

[0011] Preferably, the terminal groups of the polyamide-amine PAMAM series dendritic macromolecules are methyl or amino.

[0012] The PAMAM dendrimer used in this invention can inhibit the nucleation of calcium sulfate crystals. By affecting the nucleation rate and crystallization rate of calcium sulfate and inducing changes in crystal morphology, it can delay or prevent scale formation.

[0013] In a preferred embodiment of the present invention, the polyamide-amine PAMAM series dendritic macromolecules are prepared by the following method: PAMAM dendritic macromolecules are synthesized by a divergent method, and dendritic molecules with different alkyl diamines as the core or different generations of dendritic macromolecules with 1,6-hexanediamine as the reaction core are prepared by Michael addition and amidation condensation reactions.

[0014] Further, the alkyl diamine is 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, or 1,6-hexanediamine.

[0015] The specific preparation method using 1,2-ethylenediamine as the core is as follows:

[0016] A divergent synthesis method was adopted, in which anhydrous ethylenediamine was used as the initiating nuclear unit and anhydrous methanol was used as the solvent to carry out a Michael addition reaction with methyl acrylate to obtain 0.5 G of product. Then, the ester group was subjected to an amidation condensation reaction with ethylenediamine to obtain 1 G of product.

[0017] The reaction principle is as follows:

[0018] (1) Synthesis of 0.5G-PAMAM:

[0019]

[0020] (2) Synthesis of 1G-PAMAM:

[0021]

[0022] By repeating the above steps, 1.5G, 2G, 2.5G and 3G-PAMAM can be synthesized.

[0023] The method for preparing PAMAM dendrimers using 1,3-propanediamine, 1,4-butanediamine, or 1,6-hexanediamine as the core is the same as described above.

[0024] The present invention also provides the application of the scale inhibitor in industrial circulating water cooling systems and / or high-temperature water systems.

[0025] The scale inhibitor is used to inhibit silicate scale and / or calcium sulfate scale.

[0026] The scale inhibitor is added at a concentration of 10–80 mg / L to inhibit silicate scale. The SiO2 retention rate is tested after 24 hours. When the optimal agent concentration is 40 mg / L, the retention rate can reach over 87%, which is significantly better than commercially available products.

[0027] The scale inhibitor is added at a concentration of 2–20 mg / L to inhibit calcium sulfate scale. The scale inhibition rate against calcium sulfate is tested after 25 hours. When the optimal dosage is 10 mg / L, the scale inhibition rate can reach over 95%, which is similar to the effect of commercial products.

[0028] Within the studied temperature range of 20-100℃, PAMAM achieved a scale inhibition rate of nearly 100% for calcium sulfate scale at a concentration of 20 mg / L, indicating that dendritic macromolecules are suitable not only for industrial circulating water cooling systems but also for high-temperature water systems.

[0029] Beneficial effects:

[0030] The scale inhibitor based on dendritic macromolecules provided by this invention can effectively reduce the pollution or damage caused by silicate scale and calcium sulfate scale in industrial water, effectively extend the cleaning cycle and service life of the system, and significantly reduce the operating cost of the system. The agent is a homogeneous liquid product, making it simple to use. Attached Figure Description

[0031] Figure 1 Infrared spectra of 0.5G-PAMAM, 1.5G-PAMAM, and 2.5G-PAMAM.

[0032] Figure 2 Infrared spectra of 1.0G-PAMAM, 2.0G-PAMAM, and 3.0G-PAMAM.

[0033] Figure 3 The image shows a 1.0 G-PAMAM carbon NMR spectrum.

[0034] Figure 4 The image shows a 1.5G-PAMAM carbon NMR spectrum.

[0035] Figure 5 This is a 3.0 G-PAMAM carbon NMR spectrum. Detailed Implementation

[0036] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0037] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0038] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples are commercially available products.

[0039] Example 1 High-performance scale inhibitor

[0040] Its composition is: 1G product of PAMAM series dendritic macromolecule PAMAM-1G-Eth with 1,2-ethylenediamine as the core, added to the water sample at a concentration of 40 mg / L, prepared with deionized water.

[0041] The specific preparation steps are as follows:

[0042] (a) Synthesis of 0.5 G-PAMAM

[0043] A 250 mL round-bottom flask was cooled in an ice bath. Then, 70.0 g (0.814 mol) of methyl acrylate was added, followed by 40.0 mL of anhydrous methanol as a solvent. Under nitrogen protection, 10.0 g (0.166 mol) of ethylenediamine dissolved in 40 mL of anhydrous methanol was slowly added dropwise with stirring at a rate of approximately 1 drop / s. After the addition was complete, the mixture was stirred in an ice-water bath for 30 min, then brought to room temperature and stirred for another 48 h. After stirring was complete, the product was transferred to a distillation flask, and the solvent was removed by rotary evaporation under vacuum at 40 °C. The product was then dried at 50 °C and 13.3 Pa to obtain a pale yellow oily liquid.

[0044] (b) Synthesis of 1G-PAMAM-NH2 (i.e., PAMAM-1G-Eth)

[0045] A 500 mL round-bottom flask was cooled in ice water. Then, 150.0 g (2.496 mol) of ethylenediamine was added, followed by 200.0 mL of anhydrous methanol as solvent. Under nitrogen protection and vigorous stirring, a solution of 20.0 g (0.050 mol) of 0.5 G-PAMAM dissolved in 40.0 mL of anhydrous methanol was slowly added dropwise to the flask using a constant-pressure dropping funnel at a rate of approximately 1 drop / s. The temperature was maintained below 10 °C during the addition. After the addition was complete, the mixture was brought to room temperature and the reaction was continued with stirring for 96 h. After the reaction was complete, the product was transferred to a distillation flask. The solvent was first removed by rotary evaporation under vacuum at 40 °C, followed by rotary evaporation at 72 °C to remove excess ethylenediamine. Trace amounts of ethylenediamine were removed by azeotropic distillation using 100 mL of toluene / methanol (V / V = 9:1) solution. The product was then dried at 50 °C and 13.3 Pa to obtain a pale yellow oily liquid.

[0046] Similarly, 1.5G, 2G, 2.5G, and 3G products are synthesized using the same steps and processing methods described above.

[0047] Infrared spectra of 0.5G-PAMAM, 1.5G-PAMAM, and 2.5G-PAMAM are shown below. Figure 1 .

[0048] The half-generation PAMAM products are identical in structure and infrared spectra, except that the 0.5G version lacks an amide group. At a wavenumber of 2954 cm⁻¹... -1 The strong absorption peak at 1437 cm⁻¹ is due to the asymmetric stretching vibration of -CH₂-. -1 The presence of a corresponding -CH2- bending vibration absorption peak at 1735 cm⁻¹ confirms the presence of -CH2- in the product. -1 The strongest characteristic absorption peak of carbonyl ester appeared at 1648 cm⁻¹. -1 1541cm -1 1328cm -1 The absorption peak is the amide triad, at 1255 cm⁻¹. -1 1174cm -1 The corresponding absorption peak corresponds to the asymmetric and symmetric stretching vibrations of CN, at 1198 cm⁻¹. -1 1045cm -1 The corresponding absorption peaks are the asymmetric and symmetric stretching vibrations of CO.

[0049] Infrared spectra of 1.0G-PAMAM, 2.0G-PAMAM, and 3.0G-PAMAM are shown below. Figure 2 .

[0050] The infrared spectra of PAMAM products across the 1G, 2G, and 3G generations are very similar. At wavenumber 3284 cm⁻¹... -1 3075cm-1 The strong absorption peak observed is due to the asymmetric and symmetric stretching vibrations of NH4+, at 2934 cm⁻¹. -1 2865cm -1 The strong absorption peak at 1460 cm⁻¹ is due to the asymmetric and symmetric stretching vibrations of -CH₂-. -1 1437cm -1 The presence of a corresponding -CH2- bending vibration absorption peak at 1735 cm⁻¹ confirms the presence of -CH2- in the product. -1 The disappearance of the absorption peak at 1644 cm⁻¹ indicates that the half-generation product has undergone complete amidation. -1 1557cm -1 1358cm -1 The absorption peak is the amide triad, at 1127 cm⁻¹. -1 1035cm -1 The corresponding absorption peaks are the asymmetric and symmetric stretching vibrations of CN (secondary carbon).

[0051] 1.0G-PAMAM carbon NMR data can be found Figure 3 1.5G-PAMAM carbon NMR data can be found here. Figure 4 , 3 .0G-PAMAM carbon NMR data can be found Figure 5 .

[0052] PAMAM 1G 1 The correspondence between the absorption peaks of H-NMR is as follows: Figure 3 As shown: a 2.46; b 2.75 (N- CH 2-CH2CO); c, e 2.34; d 3.25(-CONH- CH 2-); f 1.50(-NH2); g 8.10~8.20ppm(-CON H ).

[0053] PAMAM AG1.5 1 The correspondence between the absorption peaks of HNMR is as follows: Figure 4 Shown: a, c, e, g 2.33~2.55; b, f2.75(N- CH 2-CH2CO); d 3.26(-CONH- CH 2-); h 3.65(-CO2-) CH 3); i 7.3(-CON H )ppm.

[0054] Examples 2-4 High-performance scale inhibitors

[0055] Its composition is: 1G products of PAMAM series dendritic macromolecules (PAMAM-1G-Prop, PAMAM-1G-But and PAMAM-1G-Hex) with 1,3-propanediamine, 1,4-butanediamine and 1,6-hexanediamine as the core respectively, added to the water sample at a concentration of 40 mg / L, prepared with deionized water.

[0056] The preparation method of 1G products of PAMAM-1G-Prop, PAMAM-1G-But and PAMAM-1G-Hex is as described in Example 1.

[0057] Example 5: Evaluation of Scale Inhibition Performance

[0058] This embodiment uses PAMAM-1G-Eth, PAMAM-1G-Prop, PAMAM-1G-But, and PAMAM-1G-Hex series dendritic macromolecules as scale inhibitors to evaluate their performance in a concentrated scale inhibition experiment on a high-silica solution with a pH of 7±0.1, a reaction temperature of 30℃, and a SiO2 concentration of 500 mg / L.

[0059] The scale inhibition effect of the scale inhibitors prepared in Examples 1-4 on colloidal silica was investigated using a static method. A high silica solution with a concentration of 500 mg / L SiO2 was prepared by dissolving Na2SiO3·9H2O in deionized water and then poured into several polyethylene volumetric flasks. The pH value was then adjusted to 7 ± 0.1 with hydrochloric acid, stirred evenly, and then allowed to stand in a water bath at 30°C.

[0060] The testing method for the performance of the calcium silicate scale inhibitors prepared in Examples 1-4 above is as follows: A silica standard curve was plotted according to GB / T 12149-2007 "Determination of Silicon in Industrial Circulating Cooling Water and Boiler Water - Spectrophotometric Method". The scale inhibitor was added directly and uniformly mixed with a high-silica solution of deionized water; the solution was then bathed in water for a total of 24 hours. The concentration of soluble silicic acid in the filtrate was determined using the silicomolybdenum yellow spectrophotometric method, and a blank was retained.

[0061] The experimental results are shown in Table 1.

[0062] Table 1. Experimental results of Examples 1-4

[0063] blank 159 31.8 PAMAM-1G-Eth 402 80.4 PAMAM-1G-Prop 435 87.0 PAMAM-1G-But 407 81.4 PAMAM-1G-Hex 406 81.2

[0064] As can be seen from Table 1, different types of PAMAM-1G products have very high scale inhibition rates.

[0065] Example 6: Evaluation of the scale inhibition performance of scale inhibitors at different concentrations in concentrated scale inhibition experiments.

[0066] This embodiment evaluates the performance of PAMAM series dendritic macromolecules as scale inhibitors at different concentrations in a concentrated scale inhibition experiment on a high silica solution with a pH of 7±0.1, a reaction temperature of 30℃, and a SiO2 concentration of 500mg / L.

[0067] The PAMAM-1G-Eth, PAMAM-1G-Prop, PAMAM-1G-But and PAMAM-1G-Hex prepared in Examples 1-4 were added to water samples to prepare solutions with concentrations of 30, 50 and 60 mg / L, respectively, and were prepared with deionized water.

[0068] The scale inhibition effect of the scale inhibitor on colloidal silica was investigated using a static method. A high-silica solution with a concentration of 500 mg / L SiO2 was prepared by dissolving Na2SiO3·9H2O in deionized water and then poured into several polyethylene volumetric flasks. The pH value was then adjusted to 7 ± 0.1 with hydrochloric acid, stirred thoroughly, and then allowed to stand in a water bath at 30°C.

[0069] The scale inhibitor was added directly and mixed evenly with the high-silica solution of deionized water. The solution was then bathed in water for a total of 12 hours. After sampling, the concentration of soluble silicic acid in the filtrate was determined by the silicomolybdenum yellow spectrophotometric method, and one sample was reserved as a blank.

[0070] The experimental results are shown in Table 2.

[0071] Table 2 Experimental Results

[0072]

[0073] As shown in Table 2, different PAMAM-1G scale inhibitors can achieve a scale inhibition rate of over 77% when added at concentrations of 30, 50, and 60 mg / L.

[0074] Example 7: Comparison of the stabilizing effects of scale inhibitors on soluble silica

[0075] The scale inhibitor was PAMAM-1G-Prop at a concentration of 40 mg / L, prepared with deionized water. Its stabilizing effect on soluble silica was compared with that of commercially available aminotrimethylphosphonic acid (ATMP) and polyacrylic acid (PAA) at the same concentration.

[0076] The scale inhibitor effect on colloidal silica was investigated using a static method. A high-silica solution with a concentration of 500 mg / L SiO2 was prepared by dissolving anhydrous sodium silicate in deionized water. This solution was then placed in several polyethylene volumetric flasks, and the required amount of scale inhibitor was added. The pH was then adjusted to 7 ± 0.1 with hydrochloric acid or sodium hydroxide solution, and the solution was kept at a constant temperature of 30°C.

[0077] The above-mentioned PAMAM scale inhibitor is used as follows: the scale inhibitor is added directly and mixed evenly with the high silica solution of deionized water; after a total water bath of 24 hours, the concentration of soluble silicic acid in the filtrate is determined by the molybdenum yellow spectrophotometric method.

[0078] The stabilizing effects of the product PAMAM-1G-Prop on soluble silica were compared with those of commercially available aminotrimethylphosphonic acid (ATMP) and polyacrylic acid (PAA). The experimental performance evaluation conditions were: pH 7 ± 0.1, reaction temperature 30℃, and a high-silica solution with a SiO2 concentration of 500 mg / L. The experimental results are shown in Table 3. The concentration was 40 mg / L, prepared with deionized water.

[0079] Table 3 Experimental Results

[0080] PAMAM-1G-Prop 435 87.0 ATMP 171 34.2 PAA 178 35.6

[0081] As can be seen from Table 3, the scale inhibition effect of PAMAM-type scale inhibitors is significantly better than that of ATMP and PAA.

[0082] Example 8

[0083] Its composition is: 0.5G product of PAMAM series dendritic macromolecule PAMAM-0.5G-Hex with 1,6-hexanediamine as the core, added to water samples at concentrations of 2, 10, and 20 mg / L, and prepared as a scale inhibitor with deionized water.

[0084] The preparation of PAMAM-0.5G-Hex is described in Example 1, except that the core molecule is 1,6-hexanediamine.

[0085] Example 9

[0086] Its composition is: 1.5G product of PAMAM series dendritic macromolecule PAMAM-1.5G-Hex with 1,6-hexanediamine as the core, added to water samples at concentrations of 2, 10, and 20 mg / L, and prepared as a scale inhibitor with deionized water.

[0087] The preparation of PAMAM-1.5G-Hex is described in Example 1, except that the core molecule is 1,6-hexanediamine.

[0088] Example 10

[0089] Its composition is: 2G product of PAMAM series dendritic macromolecule PAMAM-2G-Hex with 1,6-hexanediamine as the core, added to water samples at concentrations of 2, 10, and 20 mg / L, and prepared as a scale inhibitor with deionized water.

[0090] The preparation of PAMAM-2G-Hex is described in Example 1, except that the core molecule is 1,6-hexanediamine.

[0091] Example 11 Evaluation of the scale inhibition performance of the scale inhibitor on CaSO4 scale

[0092] According to SYT5673-93 "Performance Evaluation Method for Scale Inhibitors for Oilfield Use", the scale inhibition performance of the dendritic macromolecules prepared in Examples 4 and 8-10 on CaSO4 scale was evaluated.

[0093] The initial test solution contained 3000 mg / L Ca 2+ and 7200 mg / L SO4 2- Different concentrations of PAMAM scale inhibitor were added directly and mixed evenly with the solution. The pH of the solution was adjusted to 9.0 using 0.01 mol / L borax buffer. The mixture was then placed in a 70°C water bath for 25 hours. After cooling to room temperature, the mixture was filtered through a 0.22 μm filter membrane. Using calcein-phenolphthalein mixed indicator as an indicator, the Ca2+ content was titrated with 0.01 mol / L sodium ethylenediaminetetraacetate (EDTA) standard solution. 2+ Meanwhile, a blank test was conducted as a reference for experiments without scale inhibitors.

[0094] PAMAM-0.5G-Hex, PAMAM-1G-Hex, PAMAM-1.5G-Hex, and PAMAM-2G-Hex dendritic macromolecules were used as scale inhibitors at a pH of 9.0, a reaction temperature of 70°C, and an initial test solution containing 3000 mg / L Ca. 2+ and 7200 mg / L SO4 2- The scale inhibition performance was evaluated under the following conditions. The experimental results are shown in Table 4, with the scale inhibitor concentration ranging from 2 to 20 mg / L.

[0095] Table 4 Experimental Results

[0096]

[0097] As can be seen from Table 4, scale inhibitors at concentrations of 2–20 mg / L all have scale inhibition effects on CaSO4 scale.

[0098] Example 12 Comparison of scale inhibition effects of scale inhibitors on calcium sulfate at different temperatures

[0099] PAMAM-1.5G-Hex dendritic macromolecules were added to water samples at concentrations of 2, 10, and 20 mg / L, with the temperature range being 30–90 °C. The scale inhibitor's effect on calcium sulfate at different temperatures was evaluated using the method described in Example 11.

[0100] PAMAM-1.5G-Hex dendritic macromolecules were added to water samples at concentrations of 2, 10, and 20 mg / L at different temperatures to evaluate the scale inhibition performance of high-concentration calcium sulfate under pH 9.0 water conditions. The experimental results are shown in Table 5, with concentrations ranging from 2 to 20 mg / L and temperatures ranging from 30 to 90℃.

[0101] Table 5 Experimental Results

[0102]

[0103] Table 5 shows that the scale inhibitors all exhibited scale inhibition effects on CaSO4 scale within an operating temperature range of 30–90℃. Example 13: Comparison of scale inhibition effects of scale inhibitors on calcium sulfate.

[0104] PAMAM-1.5G-Hex dendritic macromolecules were compared with commercially available hexamethylenediaminetetramethylenephosphoric acid (HDTMPA) CaSO4 scale inhibitors at the same concentration. The concentrations added to the water samples were 4, 8, and 10 mg / L. Evaluation was performed using the method described in Example 11.

[0105] The scale inhibition performance of PAMAM-1.5G-Hex and commercially available hexamethylenediaminetetramethylenephosphoric acid (HDTMPA) on CaSO4 was compared at the same concentration. The experimental performance evaluation conditions were: pH 9.0, reaction temperature 70℃, and an initial test solution containing 3000 mg / L CaSO4. 2+ and 7200 mg / L SO4 2- The scale inhibition performance was evaluated under the following conditions. The experimental results are shown in Table 6. The concentration was 4–10 mg / L, and the solution was prepared with deionized water.

[0106] Table 6 Experimental Results

[0107]

[0108] As shown in Table 6, PAMAM-type scale inhibitors, when used at a concentration of 8–10 mg / L, have a scale inhibition effect similar to that of commercially available hexamethylenediaminetetramethylenephosphoric acid (HDTMPA).

[0109] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An application of a scale inhibitor based on dendritic macromolecules in a high-temperature water system, characterized in that, The scale inhibitor is prepared from dendritic macromolecules and water; the dendritic macromolecules are polyamide-amine PAMAM series dendritic macromolecules with 1,6-hexanediamine as the core; the generation of the polyamide-amine PAMAM series dendritic macromolecules is 0.5G or 1.5G; the scale inhibitor is used to inhibit calcium sulfate scale.

2. The application according to claim 1, characterized in that, The terminal group of the polyamide-amine PAMAM series dendritic macromolecules is methyl.

3. The application according to claim 1, characterized in that, The polyamide-amine PAMAM series dendritic macromolecules are prepared by the following method: PAMAM dendritic macromolecules are synthesized by a divergent method, and different generations of dendritic macromolecules with 1,6-hexanediamine as the reaction core are prepared by Michael addition and amidation condensation reactions.

4. The application according to claim 1, characterized in that, The dosage concentration of the scale inhibitor for inhibiting calcium sulfate scale is 2~20 mg / L.

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