A method for preparing a through-hole type resin

Abstract

The application discloses a preparation method of a through-hole type resin and belongs to the technical field of high polymer resin materials. The through-hole type resin is prepared through suspension polymerization and programmed temperature curing by adopting ternary composite pore-forming agents composed of toluene, normal heptane and polyethylene glycol (PEG) and optimizing the proportion of the ternary composite pore-forming agents. The resin prepared by the method has a highly through hole network, the through rate of the resin is not less than 50%, and the resin simultaneously has suitable large pore diameter, higher specific surface area and pore volume. Meanwhile, the resin maintains good mechanical stability while obtaining excellent through structure, and the preparation process has good repeatability, so that the resin provides an ideal material for high-performance adsorption separation, chromatographic analysis and catalysis and the like.

Description

Technical Field

[0001] This invention relates to a method for preparing a through-pore type resin, belonging to the field of polymer resin material technology. Background Technology

[0002] Porous resin materials, as an important class of functional polymer materials, include various types such as polystyrene-based, polyacrylate-based, polyvinyl alcohol-based, and phenolic resin-based materials, and are widely used in adsorption separation, catalyst supports, chromatographic analysis, and controlled drug release. Among them, cross-linked polymer resins, represented by polymethyl acrylate-divinylbenzene (PMA-DVB), have become a key material system in current research and practice due to their strong modifiable skeleton, high physicochemical stability, and ease of controlling the pore structure through polymerization processes. Ideal porous resins, especially for the separation and adsorption of macromolecules, need to possess a continuous and interconnected pore structure to achieve rapid mass transfer processes and high-capacity adsorption.

[0003] However, PMA-DVB resins prepared using existing technologies still face significant challenges: although porosity can be adjusted to some extent by changing the degree of crosslinking or using simple pore-forming agents, the resulting pores often lack connectivity, containing numerous closed or semi-closed pores. This makes it difficult for adsorbate molecules to penetrate deep into the particles, resulting in low utilization of effective adsorption sites and slow dynamic adsorption rates. Simultaneously, traditional methods offer limited control over pore size distribution, making it difficult to form concentrated macroporous channels suitable for macromolecular transport while maintaining a high specific surface area. Pore sizes that are too small result in high mass transfer resistance, while those that are too large decrease the adsorption capacity per unit volume, failing to synergistically optimize the dual objectives of "rapid mass transfer" and "high-capacity adsorption." Furthermore, conventional pore-forming systems are mostly limited to single or binary solvents, lacking sufficient controllability. This makes it difficult to precisely design and controllably construct pore morphology and interconnected structures, leading to low material performance repeatability and difficulty in meeting the customized pore structure requirements of different application scenarios.

[0004] Therefore, developing a method for controllable preparation of PMA-DVB resin with highly interconnected channels, suitable pore size, and high specific surface area is of great significance for promoting the practical application of this material in demanding fields such as bioseparation and environmental remediation. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a method for preparing a through-hole resin. This application utilizes a ternary composite porogen composed of toluene, n-heptane, and polyethylene glycol (PEG), and optimizes their ratio, to obtain a through-hole resin through suspension polymerization and programmed temperature curing. The resin prepared by this method possesses a highly interconnected pore network with a connectivity of not less than 50%, while simultaneously exhibiting suitable large pore size, high specific surface area, and pore volume. This resin effectively solves the problem of traditional adsorbent materials struggling to simultaneously achieve both mass transfer rate and adsorption capacity.

[0006] The first objective of this invention is to provide a method for preparing a through-pore resin, comprising the steps of: (1) Preparation of aqueous and oil phases: Polyvinyl alcohol and sodium chloride are dissolved in water to obtain an aqueous phase; Methyl acrylate, divinylbenzene, a ternary porogen, and benzoyl peroxide were mixed in a mass ratio of 58~74:16~32:90~100:1.2~1.6 to obtain an oil phase; wherein, the mass ratio of toluene, n-heptane, and polyethylene glycol in the ternary porogen was 0.5~1.5:0.5~1.5:0.5~1.5. (2) Preparation of resin: After stirring the oil phase into the aqueous phase, the temperature is first raised to 60~65℃ and reacted for 3~4 h; then the temperature is raised to 75~80℃ and reacted for 3~4 h; finally, the resin is cured at 90~95℃ for 2~3 h; after the reaction is completed, the resin is filtered, washed, sieved, pore-forming agent is removed, and dried to obtain the through-type resin.

[0007] In one embodiment, the ratio of polyvinyl alcohol, sodium chloride, and water is 4.5~5.5 g: 15~16 g: 450~550 mL.

[0008] In one embodiment, the molecular weight of polyethylene glycol is 1000~10000 Da.

[0009] In one embodiment, the mass ratio of the aqueous phase to the oil phase in step (2) is 2.5~5:1~2; the stirring is carried out at 45~50℃ until the oil droplet size is 0.2~1.2 mm; and the sieving is performed to obtain 15~80 mesh resin particles.

[0010] In one embodiment, acetone Soxhlet extraction is used to remove the porogen.

[0011] In one embodiment, the drying is performed by vacuum drying at 60-70°C for 10-14 hours.

[0012] A second object of the present invention is to provide a resin prepared by any of the methods described above.

[0013] A third objective of this invention is to provide a product containing the aforementioned through-pore type resin; the product includes a pre-packed column, bulk resin, and a screening column.

[0014] The fourth objective of this invention is to provide a method for simultaneously improving resin penetration rate, pore volume, and total pore area, comprising the steps of: (1) Preparation of aqueous and oil phases: Polyvinyl alcohol and sodium chloride are dissolved in water to obtain an aqueous phase; Methyl acrylate, divinylbenzene, a ternary porogen, and benzoyl peroxide were mixed in a mass ratio of 58~74:16~32:90~100:1.2~1.6 to obtain an oil phase; wherein, the mass ratio of toluene, n-heptane, and polyethylene glycol in the ternary porogen was 0.5~1.5:0.5~1.5:0.5~1.5. (2) Preparation of resin: After stirring the oil phase into the aqueous phase, the temperature is first raised to 60~65℃ and reacted for 3~4 h; then the temperature is raised to 75~80℃ and reacted for 3~4 h; finally, the resin is cured at 90~95℃ for 2~3 h; after the reaction is completed, the resin is filtered, washed, sieved, pore-forming agent is removed, and dried to obtain the through-type resin.

[0015] In one embodiment, the ratio of polyvinyl alcohol, sodium chloride, and water is 4.5~5.5 g: 15~16 g: 450~550 mL; the molecular weight of polyethylene glycol is 1000~10000 Da.

[0016] In one embodiment, the mass ratio of the aqueous phase to the oil phase in step (2) is 2.5~5:1~2; the stirring is carried out at 45~50℃ until the oil droplet size is 0.2~1.2 mm; and the sieving is performed to obtain 15~80 mesh resin particles.

[0017] In one embodiment, acetone Soxhlet extraction is used to remove the porogen.

[0018] In one embodiment, the drying is performed by vacuum drying at 60-70°C for 10-14 hours.

[0019] A fifth object of the present invention is to provide the application of the above-described resin and any of the methods described above in adsorption separation and chromatographic packing materials.

[0020] Beneficial effects This invention utilizes a ternary composite porogen composed of toluene, n-heptane, and polyethylene glycol (PEG), and optimizes their ratio to prepare a through-hole resin through suspension polymerization and programmed temperature curing. The resin prepared by this method exhibits a good through-hole structure (through-hole rate reaching 60%), a suitable and concentrated large pore size distribution (most probable pore size 77 nm), and a synergistic optimization of high specific surface area (90.5 m² / g) and pore volume (2.30 mL / g), thus effectively resolving the contradiction between mass transfer rate and adsorption capacity in traditional adsorption resins. Attached Figure Description

[0021] Figure 1 The mercury inlet / outlet curves and pore size distribution curves of the resin in Example 1 are shown. Figure 2 The mercury inlet / outlet curves and pore size distribution curves of the resin in Comparative Example 1 are shown. Figure 3The mercury inlet / outlet curves and pore size distribution curves of the resin in Comparative Example 2 are shown. Figure 4 The mercury inlet / outlet curves and pore size distribution curves of the resin in Comparative Example 3 are shown. Figure 5 The mercury inlet / outlet curves and pore size distribution curves of the resin in Comparative Example 4 are shown. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, where specific conditions are not specified, are generally performed under conventional conditions in the art. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar with the art.

[0023] Raw material source: Polyvinyl alcohol was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Sodium chloride, methyl acrylate, and n-heptane were purchased from Shanghai Titan Technology Co., Ltd. Divinylbenzene was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Toluene and polyethylene glycol of different molecular weights were purchased from Sinopharm Shanghai Laboratory. Benzoyl peroxide was purchased from Saen Chemical Technology (Shanghai) Co., Ltd.

[0024] The methods involved in the embodiments: 1. Measurement of total pore volume, total pore area, average pore diameter, pore diameter distribution curve, and mercury inflow / outflow volume. The total pore volume, total pore area, average pore diameter, pore size distribution curve, and mercury inflow / outflow were all measured using a Micromeritics AutoPore V 9600 mercury porosimeter to characterize the resin pore structure. 2. Specific surface area determination The resin sample was degassed under vacuum at 90℃ for 9 h, and the specific surface area of ​​the resin microspheres was tested using a Konta Nova 2000 with nitrogen as the adsorbent gas.

[0025] Example 1: Preparation of through-cell (PMA-DVB) resin 1. Preparation of the aqueous phase Dissolve 5 g of polyvinyl alcohol and 15 g of sodium chloride in 500 mL of deionized water, and stir at 70 °C in an Erlenmeyer flask to obtain an aqueous phase. 2. Preparation of the oil phase 59 g of methyl acrylate, 31 g of 80% pure divinylbenzene, 90 g of ternary porogen (toluene, n-heptane, and polyethylene glycol in a mass ratio of 1:1:1) and 1.6 g of benzoyl peroxide were mixed evenly to obtain an oil phase; wherein the molecular weight of polyethylene glycol (PEG) was 1500 Da.

[0026] 3. Preparation of through-cell (PMA-DVB) resin The oil phase was slowly poured into the water phase at a mass ratio of 3:1. The mixture was stirred at 45℃ and 170 rpm for 20 min to reduce the oil droplet size to approximately 0.2~1.2 mm. The temperature was then increased to 65℃ at a rate of 1℃ / 3 min for 3 h, followed by curing at 75℃ for 3 h. Finally, the mixture was cured at 90℃ for 3 h and filtered while hot. The resin was washed three times with 500 mL of deionized water at 60℃ and sieved to obtain 15~80 mesh resin particles. The resin was then extracted with acetone using the Soxhlet method for 12 h to remove pore-forming agents and dried in a vacuum oven at 60℃ for 12 h to obtain a through-pore resin.

[0027] Comparative Example 1: The molecular weight of polyethylene glycol (PEG) was changed to 1000 Da. The specific implementation method is the same as in Example 1, except that the molecular weight of polyethylene glycol (PEG) is changed to 1000 Da, while the other steps remain the same.

[0028] Comparative Example 2: The molecular weight of polyethylene glycol (PEG) was changed to 2000 Da. The specific implementation method is the same as in Example 1, except that the molecular weight of polyethylene glycol (PEG) is changed to 2000 Da, while the other steps remain the same.

[0029] Comparative Example 3: Changing the ratio of toluene, n-heptane, and polyethylene glycol The specific implementation method is the same as in Example 1, except that the mass ratio of toluene, n-heptane, and polyethylene glycol is changed to 1.5:0.5:1, while the other steps remain the same.

[0030] Comparative Example 4: Changing the ratio of toluene, n-heptane, and polyethylene glycol The specific implementation method is the same as in Example 1, except that the mass ratio of toluene, n-heptane, and polyethylene glycol is changed to 0.5:1.5:1, while the other steps remain the same.

[0031] Comparative Example 5: Changing the temperature The specific implementation method is the same as in Example 1, except that the heating step (3) is to first heat to 70°C and react for 3 hours, then heat to 80°C and react for 3 hours, and then react at 95°C for 2 hours.

[0032] The results showed that after the resin microspheres slowly formed in the flask, they broke down over time, and the substance in the flask became a milky white liquid, making it impossible to obtain resin particles.

[0033] Comparative Example 6: Preparation of Resin via Four-Stage Heating The specific implementation method is the same as that in Example 1, except that in step (3), the temperature is directly raised to 65°C for 4 hours, 75°C for 3 hours, 85°C for 2 hours, and 95°C for 2 hours, while the other steps remain the same.

[0034] The results showed that this heating method could not produce a milky white, usable resin. Under the tested conditions, the resin spheres were transparent, had a gel-like texture, and crumbled easily when squeezed.

[0035] Comparative Example 7: Changing the ratio of methyl acrylate to divinylbenzene The specific implementation method is the same as in Example 1, except that the ratio of methyl acrylate to divinylbenzene is changed to make the degree of crosslinking 15%, 20%, and 25%, while the other steps remain the same.

[0036] The results showed that the lower the degree of crosslinking, the more transparent and brittle the prepared resin was, and when the degree of crosslinking was less than 15%, it was almost impossible to form spheres.

[0037] Comparative Example 8: The molecular weight of polyethylene glycol (PEG) was changed to 6000 Da and 10000 Da. The specific implementation method is the same as in Example 1, except that the molecular weight of polyethylene glycol is changed to 6000 Da or 10000 Da, while the other steps remain the same.

[0038] The results showed that as the molecular weight of polyethylene glycol increased, it could not be completely dissolved in the pore-forming agent, and the prepared resin exhibited agglomeration, failing to disperse into individual resin particles.

[0039] Comparative Example 9: No polyethylene glycol added The specific implementation method is the same as in Example 1, except that polyethylene glycol is not added in step (2), while the other steps remain the same.

[0040] The results showed that when only toluene and n-heptane were used, the resin portion was transparent, and the experimental samples were of poor quality.

[0041] Example 2: Performance Testing The resins prepared in Example 1 and Comparative Examples 1-4 were subjected to performance testing.

[0042] 1. Resin pore parameter measurement The results are shown in Table 1: Table 1 Pore measurement data of resin

[0043] The results showed that the resin prepared in Example 1 had the highest pore volume, total pore area, and porosity, indicating that the pore volume and adsorption sites were the most abundant. The average pore size (70.44 nm) was in the macropore range (suitable for the molecular size and diffusion requirements of most adsorbates), and had a high degree of matching with the most probable pore size (77 nm), with uniform pore distribution.

[0044] The total open pore volume of Example 1 was 2.300 mL / g, and the resin porosity was 22.81%, which is significantly higher than that of Comparative Example 1 (pore volume 1.397 mL / g, porosity 12.25%) and Comparative Example 3 (pore volume 1.562 mL / g, porosity 14.42%). This increase in pore volume and porosity allows the resin of this invention to accommodate more target substances, effectively enhancing the resin's loading capacity for macromolecules.

[0045] The average pore size of Example 1 is 70.44 nm (belonging to the macropore category), and the most probable pore size (77 nm) matches the average pore size well, with uniform pore distribution. In contrast, the most probable pore size of Comparative Example 3 is only 23.410 nm (small pores), and the average pore size of Comparative Example 4 reaches 111.06 nm (excessively loose pores). The structure of the resin in Example 1 is suitable for the molecular size of most target substances and provides sufficient channels for substance diffusion, making it applicable to more types of separation and adsorption scenarios.

[0046] 2. Determination of mercury entry / exit curves and pore size distribution curves. The results are as follows Figures 1-5 As shown in the mercury ingress and egress curves, only the three resins with different PEG molecular weights exhibit consistent mercury ingress and egress characteristics, all showing a three-stage mercury ingress and three-stage mercury egress pattern, indicating that the phase separation-dominated pore structure formation mechanism is similar. However, the mercury ingress rate of Example 1 increases more significantly in the high-pressure zone (corresponding to the internal interconnected pore filling stage), and the mercury egress rate in the fast retreat interval (45~362 nm) of the mercury egress curve accounts for more than 60%, which is significantly higher than the resins prepared in Comparative Examples 1 and 2, confirming its superior pore connectivity. When the toluene content is too high, the mercury ingress and egress process of the resin is significantly hindered, the medium-pressure plateau segment of the mercury ingress curve is extended, and the mercury ingress rate in the high-pressure zone slows down, indicating that excessive toluene exacerbates the uneven phase separation, forming a large number of bottleneck pores and isolated pores. When the n-heptane content is too high, the mercury ingress in the micro-mesopore region decreases significantly, while the mercury ingress and egress in the macropore region increases, and the mercury egress curve shows no significant lag, indicating that n-heptane is more conducive to the continuous construction of the macroporous network, and the resin exhibits outstanding connectivity in the macroporous stage under this condition.

[0047] The pore size distribution curves show that the three resins obtained by different PEG molecular weight conditions do not differ significantly in pore size distribution, and all exhibit a bimodal distribution of mesoporous and macroporous pores, which is conducive to mass transfer and diffusion. However, when the ratio of toluene to n-heptane is changed, the most probable pore size peak shrinks, becoming significantly smaller than the average pore size. This restricts the growth scale of PEG phase domains, resulting in the disordered distribution of some large pores. This structural feature leads to a non-uniform distribution of "dense small pores and dispersed large pores" in the pores, thereby increasing the risk of a "bottleneck effect" in the mass transfer process, enhancing the fluctuation of the diffusion path of the target substance within the pores, and limiting the dynamic adsorption efficiency.

[0048] The mercury intrusion porosimetry (MIP) curves obtained from the resin prepared in Example 1 exhibit a distinct three-segment distribution. In the initial stage of the low-pressure region, the amount of mercury entering the resin surges dramatically due to the small size of the resin particles and the gaps between their stacking. As the pressure increases, a plateau appears in mercury intrusion, with the mercury penetrating the nanoscale pores on the resin surface and entering the resin interior. With continued pressure application, a rapid growth phase of mercury intrusion occurs, indicating good pore connectivity within the resin and smooth mercury entry. The mercury withdrawal phase also progresses through three stages with changing pressure: slow withdrawal, fast withdrawal, and slow withdrawal again. The fast withdrawal stage corresponds to a pore size of 362–45 nm, within which the resin exhibits good connectivity.

[0049] As can be seen from the pore size distribution curve, the pore size of the resin prepared in Example 1 is almost within 2000 nm. At this time, the corresponding pressure at the mercury intrusion curve is 90 psia. Therefore, based on the mercury intrusion and outtrusion of mercury at this pressure, it can be calculated that the pore connectivity of the resin itself is better, at about 60%.

[0050] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a through-pore resin, characterized in that, Including the following steps: (1) Preparation of aqueous and oil phases: Polyvinyl alcohol and sodium chloride are dissolved in water to obtain an aqueous phase; Methyl acrylate, divinylbenzene, a ternary porogen, and benzoyl peroxide were mixed in a mass ratio of 58~74:16~32:90~100:1.2~1.6 to obtain an oil phase; wherein, the mass ratio of toluene, n-heptane, and polyethylene glycol in the ternary porogen was 0.5~1.5:0.5~1.5:0.5~1.

5. (2) Preparation of resin: After stirring the oil phase into the aqueous phase, the temperature is first raised to 60~65℃ and reacted for 3~4 h; then the temperature is raised to 75~80℃ and reacted for 3~4 h; finally, the temperature is cured at 90~95℃ for 2~3 h; after the reaction is completed, the resin is filtered, washed, sieved, pore-forming agent is removed, and dried to obtain the through-type resin. The ratio of polyvinyl alcohol, sodium chloride, and water is 4.5~5.5 g: 15~16 g: 450~550 mL. The molecular weight of polyethylene glycol is 1000~2000 Da; In step (2), the mass ratio of the aqueous phase to the oil phase is 2.5~5:1~2; the stirring temperature is 45~50℃ until the oil droplet size is 0.2~1.2 mm; the sieving process yields 15~80 mesh resin particles.

2. The through-pore type resin prepared by the method of claim 1.

3. A product characterized in that, The product contains the through-pore type resin as described in claim 2; the product includes pre-packed columns, bulk resin, and screening columns.

4. A method for simultaneously improving resin penetration rate, pore volume, and total pore area, characterized in that, Including the following steps: (1) Preparation of aqueous and oil phases: Polyvinyl alcohol and sodium chloride are dissolved in water to obtain an aqueous phase; Methyl acrylate, divinylbenzene, a ternary porogen, and benzoyl peroxide were mixed in a mass ratio of 58~74:16~32:90~100:1.2~1.6 to obtain an oil phase; wherein, the mass ratio of toluene, n-heptane, and polyethylene glycol in the ternary porogen was 0.5~1.5:0.5~0.5:0.5~1.

5. (2) Preparation of resin: After stirring the oil phase into the aqueous phase, the temperature is first raised to 60~65℃ and reacted for 3~4 h; then the temperature is raised to 75~80℃ and reacted for 3~4 h; finally, the temperature is cured at 90~95℃ for 2~3 h; after the reaction is completed, the resin is filtered, washed, sieved, pore-forming agent is removed, and dried to obtain the through-type resin. The ratio of polyvinyl alcohol, sodium chloride, and water is 4.5~5.5 g: 15~16 g: 450~550 mL; the molecular weight of polyethylene glycol is 1000~2000 Da. In step (2), the mass ratio of the aqueous phase to the oil phase is 2.5~5:1~2; the stirring temperature is 45~50℃ until the oil droplet size is 0.2~1.2 mm; the sieving process yields 15~80 mesh resin particles.

5. The application of the resin of claim 2 and the method of claim 4 in adsorption separation and chromatographic packing materials.

Images