KR102626238B1 - Method for analyzing block copolymer purity - Google Patents

Abstract

The present invention relates to a method for analyzing the purity of a block copolymer, and relates to a block copolymer comprising a first block derived from a first monomer and a second block derived from a second monomer, a first homopolymer of the first monomer, and a second monomer. separating the first homopolymer and the second homopolymer from the mixture containing the second homopolymer; and calculating the concentrations of the separated first homopolymer and the second homopolymer, respectively, and then using them to determine the purity of the block copolymer.

Description

{Method for analyzing block copolymer purity}

The present invention relates to a method for analyzing the purity of block copolymers.

When producing block copolymers, not all single molecules are polymerized into block copolymers, and homopolymers of each component exist as by-products in the block copolymer.

Therefore, since by-products inevitably have an effect in evaluating the physical properties of block copolymers, it is important to separate these homopolymer by-products and analyze the purity of the block copolymer.

The existing SEC (Size Exclusion Chromatography) method separates polymers only by molecular weight, making it impossible to separate each component and analyze its purity.

Therefore, the purpose of the present invention is to provide a method for analyzing the purity of block copolymers that can separate the products produced during the production of block copolymers into each component and analyze the purity accordingly.

In order to achieve the above-described object, the present invention provides a block copolymer comprising a first block derived from a first monomer and a second block derived from a second monomer, a first homopolymer of the first monomer, and a second block of the second monomer. Separating the first homopolymer and the second homopolymer from the mixture containing the homopolymer; and calculating the concentrations of the separated first homopolymer and the second homopolymer, respectively, and then using them to determine the purity of the block copolymer.

In the present invention, the mixture can be produced through a polymerization reaction of the first monomer and the second monomer.

In the present invention, the first monomer may be an acrylic monomer and the second monomer may be a styrene monomer.

In the present invention, separation can be performed using GPEC (Gradient Polymer Elution Chromatography) method.

In the GPEC method of the present invention, a non-polar column is used as the stationary phase, and a mixed solvent of a non-polar solvent and a polar solvent is used as the mobile phase, and separation can be performed under concentration gradient conditions that increase the ratio of the non-polar solvent during separation.

In the present invention, the purity of the block copolymer can be obtained by the following formula.

[Equation 1]

Purity (%) = [(C _t - C ₁ - C ₂ ) / C _t ] × 100(%)

= {[C _t - (A ₁ /ε ₁ ) - (A ₂ /ε ₂ )] / C _t } × 100(%)

In the above equation, C _t is the total concentration of the mixture, C ₁ is the concentration of the first homopolymer, C ₂ is the concentration of the second homopolymer, A ₁ is the peak area at the maximum absorption wavelength of the first homopolymer, and ε ₁ is the concentration of the first homopolymer. The extinction coefficient at the maximum absorption wavelength of the homopolymer, A ₂ , is The peak area at the maximum absorption wavelength of the second homopolymer, ε ₂ , is This is the extinction coefficient at the maximum absorption wavelength of the second homopolymer.

In the present invention, the extinction coefficient can be determined by selecting two or more homopolymers with different molecular weights for separate homopolymers of known molecular weight, then calculating the extinction coefficient for each molecular weight, and then applying the average value.

When selecting a homopolymer in the present invention, the lowest molecular weight of the homopolymer is 1,000 to 8,000 g/mol, the maximum molecular weight of the homopolymer is 10,000 to 30,000 g/mol, and the molecular weight difference between adjacent homopolymers is 1,000 to 1,000 g/mol. It can be set to 8,000 g/mol.

In the present invention, when the block copolymer purity analysis is performed multiple times, the standard deviation of the block copolymer purity may be 1% or less.

According to the present invention, it is possible to separate the products produced during the production of block copolymers into each component and analyze their purity accordingly.

Figure 1 is a GPEC chromatogram of block copolymers and each homopolymer, (a) showing PDPM-b-PPFS, (b) showing PPFS, and (c) showing PDPM.
Figure 2 is a GPEC chromatogram according to wavelength, (a) showing UV 278 nm and (b) showing UV 260 nm.
Figure 3 shows the extinction coefficient according to the molecular weight of PDPM.
Figure 4 shows the extinction coefficient according to the molecular weight of PPFS.
Figure 5 shows the results of block copolymer purity analysis repeated 15 times.

Hereinafter, the present invention will be described in detail.

The block copolymer purity analysis method according to the present invention may consist of a separation step and an analysis (calculation) step.

First, in the separation step, a mixture containing a block copolymer including a first block derived from the first monomer and a second block derived from the second monomer, a first homopolymer of the first monomer, and a second homopolymer of the second monomer. Separate the first homopolymer and the second homopolymer. A block copolymer is formed from two or more types of monomers, and may refer to a polymer in which units of the same monomer are connected sequentially to form a block. Homopolymer may refer to a homopolymer formed from one type of monomer.

The mixture may be produced by polymerization of the first monomer and the second monomer, that is, the mixture may be a polymerization reaction product. The mixture (polymerization reaction product) may include a block copolymer as the target product and a homopolymer as a by-product (first homopolymer and second homopolymer). The polymerization product is free of unreacted monomers and random copolymers. Unreacted monomers are removed during the polymerization process, and random copolymers are not generated during the polymerization process.

For example, an acrylic monomer can be used as the first monomer, and for example, (alkyloxy)phenyl (meth)acrylate can be used as an acrylic monomer. Specifically, as in the example, 4-(dodecyloxy)phenyl methacrylate (DPM: 4-(dodecyloxy)phenyl methacrylate) can be used as the first monomer, and accordingly, the first block and the first homopolymer are poly[ It may be 4-(dodecyloxy)phenyl methacrylate] (PDPM: poly[4-(dodecyloxy)phenyl methacrylate]).

As the second monomer, for example, a styrene-based monomer can be used, and as the styrene-based monomer, for example, halostyrene can be used. Specifically, as in the example, pentafluorostyrene (PFS: pentafluorostyrene) can be used as the second monomer, and accordingly, the second block and the second homopolymer are poly (pentafluorostyrene) (PPFS: poly(pentafluorostyrene)). It can be.

The method of producing the block copolymer is not particularly limited. For example, block copolymers can be polymerized by LRP (Living Radical Polymerization), for example, using an organic rare earth metal complex as a polymerization initiator, or using an organic alkali metal compound as a polymerization initiator to form an alkali metal or alkaline earth metal. Anionic polymerization synthesized in the presence of an inorganic acid salt such as a salt of ARGET (Activators Regenerated by Electron Transfer) Atom Transfer Radical Polymerization (ATRP), which uses an atom transfer radical polymerization agent as a polymerization control agent but performs polymerization under an organic or inorganic reducing agent that generates electrons. Atomic Transfer Radical Polymerization (ATRP), ICAR (Initiators) for continuous activator regeneration), atom transfer radical polymerization (ATRP), polymerization by reversible addition/fragmentation chain transfer (RAFT) using an inorganic reducing agent, and organic reversible addition/fragmentation chain transfer (RAFT) agents. There is a method using a tellurium compound as an initiator, and an appropriate method can be selected and applied among these methods.

For example, the block copolymer can be prepared by polymerizing reactants containing monomers capable of forming polymer segments by living radical polymerization in the presence of a radical initiator and a living radical polymerization reagent. The manufacturing process of the polymer segment copolymer may further include, for example, a process of precipitating the polymerization product generated through the above-described process in a non-solvent.

The type of radical initiator is not particularly limited and can be appropriately selected in consideration of polymerization efficiency, and includes, for example, azo compounds such as AIBN (azobisisobutyronitrile), 2,2'-azobis-2,4-dimethylvaleronitrile, etc.; Peroxide series such as benzoyl peroxide (BPO), di-t-butyl peroxide (DTBP), etc. can be used.

Living radical polymerization processes include, for example, methylene chloride, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, benzene, toluene, acetone, chloroform, tetrahydrofuran, dioxane, monoglyme, diglyme, dimethylformamide, It can be carried out in a solvent such as dimethyl sulfoxide, dimethylacetamide, etc.

Non-solvents include, for example, alcohols such as methanol, ethanol, normal propanol, isopropanol, etc.; Glycols such as ethylene glycol; Hydrocarbons such as n-hexane, cyclohexane, and n-heptane; Ether series such as petroleum ether, etc. may be used.

Separation can be performed using a chromatographic method, preferably GPEC (Gradient Polymer Elution Chromatography). Specifically, in the GPEC method, a non-polar column is used as the stationary phase, and a mixed solvent of non-polar and polar solvents is used as the mobile phase, and separation can be performed under concentration gradient conditions that increase the ratio of the non-polar solvent during separation.

A non-polar column may use a C18 column or C8 column containing porous silica particles (beads) bonded or coated with a C18 series compound or a C8 series compound depending on the carbon number as a packing material. The particle size may be 1 to 10 μm. The pore size of the particle may be 50 to 500 Å.

A non-polar solvent may mean a solvent with relatively low polarity among mixed solvents, for example, a solvent with lower polarity than acetonitrile (ACN). Specifically, polar solvents and non-polar solvents can be distinguished based on dioxane. In other words, solvents with higher polarity than dioxane can be classified as polar solvents, and solvents with lower polarity than dioxane can be classified as non-polar solvents.

As polar solvents, which are solvents with higher polarity than dioxane, acetonitrile (ACN), water, methanol, acetic acid, ethanol, isopropanol, acetone, etc. can be used. Although it varies depending on the type of monomer of the block copolymer, acetonitrile (ACN) is preferably used as a polar solvent.

Nonpolar solvents that are less polar than dioxane include tetrahydrofuran (THF), methyl ethyl ketone, phenol, n-butanol, ethyl acetone, ethyl ether, nitromethane, chloroform, benzene, toluene, xylene, carbon tetrachloride, and disulfide. Carbon, cyclohexane, n-hexane, n-heptane, kerosene, etc. can be used. Although it varies depending on the type of monomer of the block copolymer, tetrahydrofuran (THF) can be preferably used as a nonpolar solvent.

The concentration gradient condition may vary depending on the type of monomer of the block copolymer, etc., and may be, for example, a concentration gradient condition that increases the ratio of the non-polar solvent during separation. Specifically, the volume ratio of non-polar solvent to polar solvent may initially (during loading) be 0:100 to 70:30, and subsequently (during separation) may be 70:30 to 100:0. More specifically, the volume ratio of non-polar solvent to polar solvent may initially (during loading) be 55:45 to 65:35 and subsequently (during separation) may be 75:25 to 85:15. Solvent ratio changes can be made continuously and/or intermittently at a constant rate.

In this way, after block copolymer polymerization, by-products and pure block copolymers can be separated using a chromatography method, and quantitative analysis is possible by using the above-described chromatography method. Of the two homopolymers that exist as by-products of block copolymers, one homopolymer can be eluted before the solvent peak by the SEC mechanism, and the block copolymer and the other homopolymer can be eluted from the column packing. Due to the interaction with , each component can be separated by eluting after the solvent peak (at a later time).

Next, calculate the concentrations of the separated first homopolymer and second homopolymer, respectively. The concentration of the homopolymer can be calculated from the peak area at the maximum absorption wavelength (λ _max ) of the homopolymer and the extinction coefficient at the maximum absorption wavelength. Specifically, the homopolymer concentration (C) may be = peak area (A)/extinction coefficient (ε).

The maximum absorption wavelength (λ _max ) may refer to the wavelength that represents the greatest absorbance or absorption intensity in a chromatogram (e.g., time (horizontal axis) - absorbance (vertical axis) graph, etc.). Peak area may refer to the area at the maximum peak. The maximum peak may mean that the peak height (maximum absorbance or absorption intensity) is the maximum among several peaks. If the largest peak is adjacent to another peak, it can be divided based on the boundary point of the two peaks. For example, in Figure 2, the boundary of the maximum peak is indicated by a dotted line, and the area of the maximum peak is an area surrounded by dotted lines and solid peak lines.

The extinction coefficient can be calculated by selecting two or more types of homopolymers with different molecular weights for separate homopolymers, and then applying the average value of the extinction coefficient for each molecular weight. Specifically, since differences in extinction coefficient may occur depending on molecular weight due to the influence of end groups, two or more types of homopolymers of each monomer component with different molecular weights can be selected to obtain the extinction coefficient, and the average value can be obtained.

Molecular weight may refer to number average molecular weight (Mn). The number average molecular weight may be a converted value to standard polystyrene measured using, for example, GPC (Gel Permeation Chromatograph).

The homopolymer used to calculate the extinction coefficient may not be a polymerization product, but may be a separately manufactured or purchased homopolymer. Therefore, the average value of the extinction coefficient for each molecular weight can be obtained by selecting a plurality of homopolymers for which information such as molecular weight is already known.

When calculating the concentration of the homopolymer separated from the polymerization reaction product, if the average value of the extinction coefficient for each molecular weight is applied, the influence of the molecular weight can be minimized and the concentration of the homopolymer can be obtained accurately and reproducibly.

Since extinction coefficient (ε) = peak area (A)/homopolymer concentration (C), the extinction coefficient can be calculated by preparing a homopolymer with a known molecular weight at a specific concentration and then obtaining the peak area from the GPEC chromatogram.

The number of homopolymers having different molecular weights may be, for example, 2 to 10, preferably 3 to 8, and more preferably 4 to 6.

When selecting homopolymers by molecular weight, the lowest molecular weight of the homopolymer is, for example, 1,000 to 8,000 g/mol, preferably 2,000 to 7,000 g/mol, more preferably 3,000 to 6,000 g/mol. It can be set to .

When selecting homopolymers by molecular weight, the maximum molecular weight of the homopolymer is, for example, 10,000 to 30,000 g/mol, preferably 12,000 to 25,000 g/mol, more preferably 15,000 to 22,000 g/mol. It can be set to .

When selecting homopolymers by molecular weight, the molecular weight difference between each adjacent homopolymer is, for example, 1,000 to 8,000 g/mol, preferably 2,000 to 7,000 g/mol, more preferably 3,000 to 6,000. It can be set in g/mol.

Next, calculate the purity of the block copolymer using the calculated concentrations of the first homopolymer and the second homopolymer. The purity of the block copolymer can be obtained by the following formula.

[Equation 1]

Purity (%) = [(C _t - C ₁ - C ₂ ) / C _t ] × 100(%)

= {[C _t - (A ₁ /ε ₁ ) - (A ₂ /ε ₂ )] / C _t } × 100(%)

In the above equation,

C _t is the total concentration of the mixture (concentration of the entire sample), and in this case, the concentration of the entire sample can be calculated from the weight of the pretreated sample/solution.

C ₁ is the concentration of the first homopolymer (e.g. PDPM) separated from the mixture, and this concentration can be calculated from peak area/extinction coefficient.

C ₂ is the concentration of the second homopolymer (e.g. PPFS) separated from the mixture, which can be calculated from peak area/extinction coefficient.

A ₁ is the peak area of the first homopolymer (e.g., PDPM) separated from the mixture at the maximum absorption wavelength (λ _max1 ) (e.g., UV 278 nm).

ε ₁ is the extinction coefficient of the first homopolymer (e.g., PDPM) separated from the mixture at the maximum absorption wavelength (λ _max1 ) (e.g., UV 278 nm), and this extinction coefficient is as described above. This is the average value of the extinction coefficient for each molecular weight as described above.

A ₂ is It is the peak area of the second homopolymer (e.g., PPFS) separated from the mixture at the maximum absorption wavelength (λ _max2 ) (e.g., UV 260 nm).

ε ₂ is It is the extinction coefficient of the second homopolymer (e.g., PPFS) separated from the mixture at the maximum absorption wavelength (λ _max2 ) (e.g., UV 260 nm), and this extinction coefficient is as described above. This is the average value of extinction coefficient for each molecular weight.

When the block copolymer purity analysis as described above is performed multiple times, the standard deviation of the block copolymer purity is 1% or less, which confirms excellent reproducibility.

Hereinafter, the present invention will be described in more detail through examples.

[Example]

A mixture of PDPM-b-PPFS block copolymer, PDPM homopolymer, and PPFS homopolymer obtained by polymerizing DPM as the first monomer and PFS as the second monomer was separated using GPEC.

The degree of interaction can be determined by selecting relatively non-polar tetrahydrofuran (THF) and polar acetonitrile (ACN) when using a non-polar C18 column as the stationary phase, increasing the volume ratio of THF to 60% over time. It was controlled through gradient conditions increasing from to 80%.

Among the two homopolymers that exist as by-products of the block copolymer, one homopolymer elutes before the solvent peak by the SEC mechanism, and the block copolymer and the other homopolymer elute in the solvent by interaction with the column packing. Each component was separated by elution after the peak.

A photo diode array (PDA) (260 nm, 278 nm) was used as a detector. The purity of the block copolymer was calculated by subtracting the concentration of each homopolymer from the total sample concentration to calculate the concentration of the pure block copolymer.

Figures 1 and 2 show the results of establishing block copolymer separation conditions using GPEC, and show a GPEC-UV chromatogram.

As can be seen in Figure 1, conditions were established to separate the block copolymer and each homopolymer in the sample by component.

Figure 2 is a chromatogram of the same sample detected at UV 278 nm and 260 nm. For PDPM with λ _max of 278 nm, the content (concentration) was calculated from the chromatogram at 278 nm, and for PPFS with λ _max of 260 nm, it was 260 nm. The content (concentration) was calculated from the nm chromatogram.

Table 1 shows the analysis conditions. The solvent gradient conditions in Table 1 mean that the THF/ACN mixed solvent was loaded at 60/40 v/v% and then continuously adjusted to 80/20 v/v% for 15 minutes.

column Capcellpak C18 (5 ㎛, 4.6×250 mm, 120 Å) menstruum THF/ACN = 60/40 (0 minutes) → 80/20 (15 minutes) flow rate 0.6mL/min column temperature 35℃ Injection amount 100 μl

Figures 3 and 4 show the extinction coefficient analysis of separately polymerized homopolymers, not the polymerization reaction products, and show the extinction coefficients according to the molecular weight of each homopolymer. In Figure 3, the molecular weight difference between each PDPM homopolymer was set to 5.9k, 3.8k, and 6k. In Figure 4, the molecular weight difference between each PPFS homopolymer is set to 3.7k, 3.3k, and 4.9k. As shown in Figures 3 and 4, the λ _max of each homopolymer is 278 nm (PDPM) and 260 nm (PPFS). The extinction coefficient was calculated. Specifically, since differences in extinction coefficient may occur depending on molecular weight due to the influence of the terminal group, four types of homopolymers of each monomer component with different molecular weights were selected, prepared at the concentrations shown in the table, and then GPEC chromatograms were obtained. After obtaining the peak area, each extinction coefficient was calculated from the formula of extinction coefficient (ε) = peak area (A) / homopolymer concentration (C), and the average value was obtained.

Figure 5 shows the results of block copolymer purity analysis using GPEC, and the block copolymer purity was obtained by the following equation.

[Equation 2]

In the above equation,

C _total is the concentration of the entire sample (calculated from the weight of the pretreated sample/solution),

C _PDPM is PDPM concentration (calculated as peak area/extinction coefficient),

C _PPFS is the PPFS concentration (calculated as peak area/extinction coefficient);

A _278,PDPM is the PDPM peak area at UV 278 nm,

ε _278,PDPM is the PDPM extinction coefficient at UV 278 nm (average value in Figure 3),

A _260,PPFS is the PPFS peak area at UV 260 nm,

ε _260,PPFS is the PPFS extinction coefficient at UV 260 nm (average value in Figure 4).

As shown in Figure 5, as a result of analyzing the purity of the same sample 15 times from the above purity calculation formula, the purity standard deviation (SD) was 0.6% and the relative standard deviation (RSD) was 0.7%, showing excellent reproducibility. Confirmed.

Claims (9)

A block copolymer comprising a first block derived from a first monomer and a second block derived from a second monomer, a first homopolymer of the first monomer, and a second homopolymer of the second monomer, the first homopolymer and separating the second homopolymer; and
It includes calculating the concentrations of the separated first homopolymer and the second homopolymer, respectively, and then using these to determine the purity of the block copolymer,
Separation is performed using GPEC (Gradient Polymer Elution Chromatography) method,
Block copolymer purity analysis method determines the purity of the block copolymer using the following formula:
[Equation 1]
Purity (%) = [(C _t - C ₁ - C ₂ ) / C _t ] × 100(%)
= {[C _t - (A ₁ /ε ₁ ) - (A ₂ /ε ₂ )] / C _t } × 100(%)
In the above equation, C _t is the total concentration of the mixture, C ₁ is the concentration of the first homopolymer, C ₂ is the concentration of the second homopolymer, A ₁ is the peak area at the maximum absorption wavelength of the first homopolymer, and ε ₁ is the concentration of the first homopolymer. The extinction coefficient at the maximum absorption wavelength of the homopolymer, A ₂ , is The peak area at the maximum absorption wavelength of the second homopolymer, ε ₂ , is This is the extinction coefficient at the maximum absorption wavelength of the second homopolymer. According to paragraph 1,
A method for analyzing the purity of a block copolymer in which the mixture is produced by the polymerization reaction of the first monomer and the second monomer. According to paragraph 1,
A method for analyzing the purity of a block copolymer in which the first monomer is an acrylic monomer and the second monomer is a styrene monomer. delete According to paragraph 1,
In the GPEC method, a block copolymer purity analysis method uses a non-polar column as the stationary phase, a mixed solvent of non-polar and polar solvents as the mobile phase, and separates under concentration gradient conditions that increase the proportion of the non-polar solvent during separation. delete According to paragraph 1,
The extinction coefficient is a block copolymer purity analysis method that selects two or more homopolymers with different molecular weights for separate homopolymers of known molecular weight, calculates the extinction coefficient for each molecular weight, and then applies the average value. In clause 7,
When selecting a homopolymer, the lowest molecular weight of the homopolymer is 1,000 to 8,000 g/mol, the maximum molecular weight of the homopolymer is 10,000 to 30,000 g/mol, and the molecular weight difference between adjacent homopolymers is 1,000 to 8,000 g. Block copolymer purity analysis method set to /mol. According to paragraph 1,
A block copolymer purity analysis method in which the standard deviation of block copolymer purity is 1% or less when the block copolymer purity analysis is performed multiple times.