Method for preparing macroporous polymethyl methacrylate

Abstract

A method for preparing macroporous polymethyl methacrylate (PMMA) particles includes the steps of: (a) dissolving a polymethyl methacrylate polymer and Pluronic polymer into an organic solvent; (b) introducing the mixed solution of step (a) to an aqueous solution containing a surfactant to carry out emulsion polymerization; (c) heating the resultant product of step (b) to allow evaporation of the organic solvent; and (d) washing and drying the porous polymethyl methacrylate particles remaining after the evaporation.

Claims

1. A method for preparing macroporous polymethyl methacrylate (PMMA) particles, comprising the steps of: (a) dissolving a polymethyl methacrylate polymer and a triblock copolymer of ethylene oxide-propylene oxide-ethylene oxide into an organic solvent; (b) introducing the mixed solution of step (a) to an aqueous solution containing a surfactant and mixing them to carry out emulsification; (c) heating the resultant product of step (b) to allow evaporation of the organic solvent; and (d) washing and drying the remaining product of step (c) to obtain the macroporous polymethyl methacrylate particles each having a plurality of macropores.

2. The method for preparing macroporous polymethyl methacrylate particles according to claim 1, wherein the polymethyl methacrylate polymer and the triblock copolymer are used in step (a) at a weight ratio of 9:1-1:9.

3. The method for preparing macroporous polymethyl methacrylate particles according to claim 1, wherein the organic solvent in step (a) is selected from the group consisting of methylene chloride, n-hexanone, methyl isopropyl ketone, toluene and isoamyl alcohol.

4. The method for preparing macroporous polymethyl methacrylate particles according to claim 1, wherein the organic solvent in step (a) is used at a ratio (w/v) of 0.01-1 g/mL based on a total weight of the polymethyl methacrylate and the triblock copolymer.

5. The method for preparing macroporous polymethyl methacrylate particles according to claim 1, wherein the surfactant in step (b) is at least one selected from the group consisting of polyvinyl alcohol, polyacrylic acid, vinyl acetate copolymer, ethyl cellulose, hydroxypropyl cellulose, polyvinyl pyrrolidone, polyvinyl methyl ether and polyethylene imine.

6. The method for preparing macroporous polymethyl methacrylate particles according to claim 1, wherein the surfactant in step (b) is used in an amount of 0.01-10.0 wt % (w/v) based on a volume of aqueous part in the aqueous solution.

7. The method for preparing macroporous polymethyl methacrylate particles according to claim 1, wherein the emulsification in step (b) is carried out under agitation at 1,000-10,000 rpm.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic view illustrating a method for preparing macroporus polymethyl methacrylate (PMMA).

(2) FIG. 2 shows the appearance of polymethyl methacrylate particles before emulsification.

(3) FIG. 3 shows the appearance of porous particles as a function of the weight ratio of PMMA to Pluronic F127 (a: Example 2, b: Example 3, c: Example 1, d: Example 4).

(4) FIG. 4 shows the appearance of porous particles as a function of the volumetric content of solvent (a: Example 5, b: Example 1, c: Example 6, d: Example 7).

BEST MODE

(5) Exemplary embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth therein.

Example 1: Preparation of Porous PMMA Particles

(6) First, provided is 600 mL of 0.5% (w/v) aqueous surfactant solution of polyvinyl alcohol (PVA) (88% hydrolyzed, molecular weight: 146,000-186,000). Next, 20 mg of polymethyl methacrylate (PMMA, molecular weight 50,000) and 200 mg of Pluronic (Pluronic F-127) are introduced to a 20 mL beaker. Herein, the Pluronic denotes a triblock copolymer of ethylene oxide-propylene oxide-ethylene oxide. Then, 4 mL of methylene chloride (MC) is added thereto. The 20 mL beaker is covered with a lid, sealed with Teflon tape and agitated so that the reaction materials are dissolved completely. The resultant solution is introduced to a preliminarily prepared 0.5% (w/v) PVA solution and emulsification is carried out by using a homogenizer (high-speed agitator) at 5000 rpm for 10 minutes. The resultant emulsion is introduced to a beaker or crystallizing dish, transferred directly to a fume hood, and agitated at 37 C. under 300 rpm or higher for 3 hours to allow evaporation of the organic solvent. The emulsion is subjected to centrifugal separation under 1,000 g for 20 minutes. After the supernatant is removed, 10 mL of distilled water is added to carry out redispersion, and the resultant dispersion is introduced to a 50 mL tube. To remove Pluronic remaining in the tube containing the dispersion obtained by removing the supernatant after the centrifugal separation, 10 mL of distilled water is further added to carry out washing, and then the resultant product is added to the same 50 mL tube. Then, centrifugal separation is carried out at 1,000 g for 10 minutes. The supernatant is removed, and redispersion and washing are carried out by using 50 mL of distilled water. The washing procedure is repeated twice. The thus washed porous microparticles are subjected to freeze drying to remove water completely. The above procedure is shown in FIG. 1 in detail.

Example 2: Preparation of Porous PMMA Depending on Ratio of PMMA to Pluronic

(7) Porous nanoparticles are provided in the same manner as Example 1, except that polymethyl methacrylate (PMMA, molecular weight 50,000) and Pluronic (Pluronic F-127) are introduced in an amount of 280 mg and 120 mg, respectively.

Example 3: Preparation of Porous PMMA Depending on Ratio of PMMA to Pluronic

(8) Porous nanoparticles are provided in the same manner as Example 1, except that polymethyl methacrylate (PMMA, molecular weight 50,000) and Pluronic (Pluronic F-127) are introduced in an amount of 240 mg and 160 mg, respectively.

Example 4: Preparation of Porous PMMA Depending on Ratio of PMMA to Pluronic

(9) Porous nanoparticles are provided in the same manner as Example 1, except that polymethyl methacrylate (PMMA, molecular weight 50,000) and Pluronic (Pluronic F-127) are introduced in an amount of 160 mg and 240 mg, respectively.

Example 5: Preparation of Porous PMMA Depending on Addition of Solvent (Methylene Chloride, MC)

(10) Porous nanoparticles are provided in the same manner as Example 1, except that methylene chloride (MC) is used in an amount of 3 mL.

Example 6: Preparation of Porous PMMA Depending on Addition of Solvent (Methylene Chloride, MC)

(11) Porous nanoparticles are provided in the same manner as Example 1, except that methylene chloride (MC) is used in an amount of 5 mL.

Example 7: Preparation of Porous PMMA Depending on Addition of Solvent (Methylene Chloride, MC)

(12) Porous nanoparticles are provided in the same manner as Example 1, except that methylene chloride (MC) is used in an amount of 6 mL.

Test Example 1: Physical Properties of Porous PMMA Particles Depending on Ratio of PMMA to Pluronic

(13) PMMA particles are provided according to Example 1 to Example 4, and each type of particles is determined for the appearance, oil absorption and particle size. Based on the test results, the optimum proportion of polymer is determined. Then, the PMMA particles according to Example 5 to Example 7 are tested to determine the optimum content of methylene chloride (MC) used for emulsification considering the appearance, oil absorption and particle size.

(14) The physical properties are determined as follows.

(15) Appearance:

(16) The porosity of particles is determined at the outer surface thereof by the naked eyes, and classified into grades of good, medium and bad. When the particles have high porosity at the outer surface thereof, they are classified into good. When the particles have medium porosity and poor porosity, they are classified into medium and bad, respectively.

(17) Oil Absorption:

(18) 1 g of dried porous PMMA is weighed and put on an aluminum foil dish. Then, liquid paraffin is added dropwise thereto and the oil is mixed with powder to evaluate the oil absorption. The time point where the oil is not absorbed to the powder any more but is present as drops is taken as the end point. Oil absorption is measured five times, and the average and standard deviation are calculated.

(19) Particle Size:

(20) Scanning electron microscopy (SEM) is used to analyze particle sizes.

(21) Pore Size:

(22) The relative size of pores based on the scale bar in SEM is obtained by using the average and standard deviation.

(23) The physical properties of the starting PMMA before emulsification are shown in Table 1. In Table 1, the appearance and particle size are observed and calculated based on the SEM image of FIG. 2.

(24) TABLE-US-00001 TABLE 1 Oil absorption Particle size Appearance (cc/g) (m) Starting PMMA Uniform 0.65 cc/g (n = 5) 10-50 appearance No porous structure

(25) In addition, Table 2 shows the physical properties of porous PMMA as a function of the ratio of PMMA/Pluronic. The porous appearance, particle size and pore size are evaluated based on FIG. 3.

(26) TABLE-US-00002 TABLE 2 PMMA/ Pluronic Oil Particle F127 absorption size Pore size weight ratio Appearance (cc/g) (m) (nm) Ex. 1 5/5 Good 4.24 0.16 5-15 1323.5 223.8 (n = 20) Ex. 2 7/3 Bad 0.94 0.09 5-15 285.7 100.4 (n = 10) Ex. 3 6/4 Bad 1.10 0.13 5-15 218.8 80.7 (n = 10) Ex. 4 4/6 Medium 3.84 0.13 5-15 1023.8 115.0 (n = 20)

(27) As shown in Table 2, Example 1 shows a high oil absorption of about 4.2 cc/g and has a particle size of about 5-15 m.

(28) In addition, Example 1 has the largest pore size. It can be said that Example 1 having large pores shows high oil absorption. However, it is thought that such high oil absorption results from the uniformity and number of pores appearing on the surface and the characteristic internal structure rather than pore size. In fact, as can be seen from FIG. 3, Example 1 has a larger number of pores and more uniform pore pattern on the surface as compared to Example 4.

(29) Further, the physical properties of porous PMMA particles as a function of the content of methylene chloride are shown in Table 3. The porous appearance, particle size and pore size are evaluated based on FIG. 4.

(30) TABLE-US-00003 TABLE 3 MC Particle content Oil absorption size Pore size (mL) Appearance (cc/g) (m) (nm) Ex. 1 4 Good 4.24 0.16 5-15 1323.5 223.8 (n = 20) Ex. 5 3 Medium 3.23 0.10 5-15 1710.5 248.9 (n = 20) Ex. 6 5 Medium 3.40 0.11 5-15 1578.9 307.8 (n = 20) Ex. 7 6 Medium 2.83 0.11 5-15 989.1 217.1 (n = 20)

(31) As shown in Table 3, the maximum value of oil absorption exists as a function of the content of methylene chloride (MC) as a solvent. In addition, when introducing an excessively large amount of solvent, no porosity is observed. In this test, the pore size of Example 5 or 6 is larger as compared to Example 1. However, it can be said that Example 1 has a larger number of pores and more uniform pores on the surface, and thus it shows a higher oil absorption.

Test Example 2: Determination of Oil Control Effect of Porous PMMA

(32) Example 1 that shows the highest oil absorption among Example 1 to Example 7 is tested for its oil control effect as compared to the starting PMMA.

(33) TABLE-US-00004 TABLE 4 Control Test Sample Talc (%) 97 95 Oil Binder (%) 3 3 Porous powder (Ex. 1) (%) 2

(34) Three healthy male adults participate in the test as subjects, and 7 mg of the sample prepared by using the composition of Table 4 is weighed precisely and applied to the forehead of each subject. Then, the amount of oil is measured with time and the average is calculated. The amount of oil is measured by using Sebumeter (Cosmomed, Germany).

(35) TABLE-US-00005 TABLE 5 Oil controllability (%) 0 h 1 h 2 h 4 h 6 h Control 100 267 544 800 1556 Test Sample 100 269 375 581 644

(36) The test results are shown in Table 5. The oil controllability as a function of time is shown by relative evaluation based on the initial amount of oil of each subject. After testing the oil controllability after 6 hours, the test sample containing 2% of Example 1 shows an effect about 2.5 times higher as compared to of the control.