KR102501106B1 - Method for preparation of poly(disulfide) - Google Patents

Abstract

The present invention relates to a method for preparing poly(disulfide) having a narrow molecular weight distribution, a poly(disulfide) having a controlled molecular weight prepared thereby, and a use thereof.

Description

Method for preparing poly(disulfide) {Method for preparation of poly(disulfide)}

The present invention relates to a method for preparing poly(disulfide) having a narrow molecular weight distribution, a poly(disulfide) having a controlled molecular weight prepared thereby, and a use thereof.

Disulfides are considered dynamic covalent bonds with conditional reactivity or meta-stability. It is a reasonably strong bond with typical bond dissociation energies of 60 kcal mol ⁻¹ , which can sufficiently maintain molecular integrity. On the other hand, it is readily cleaved or exchanged with other bonds in the presence of physical stimuli (eg, light, heat, mechanical force, etc.) or chemical stimuli (eg, radicals, nucleophiles, etc.) can overcome the dissociation energy barrier. In particular, the reversibility of oxidative coupling and reductive degradation between a disulfide and two thiols is an important factor in the structural integrity and controlled reactivity of proteins.

Interesting properties of disulfides are being investigated for applications in polymer or materials science. Disulfides act as cross-linkers between polymer chains, enhancing the stiffness of polymer networks, as shown in vulcanized rubber or disulfide-based hydrogels. For drug delivery, various pharmaceuticals can be bound to polymers or proteins through disulfide bonds. When appropriate signals are applied to the disulfide-based material in spatiotemporal manners, the disulfide bonds break, disrupting the polymer network structure or releasing the active drug from the drug carrier. UV-responsive self-healing gels that respond to high glutathione concentrations around cancerous tissues or in the cytosol; Both nanogels and antibody-drug conjugates are at the forefront of materials and pharmaceuticals.

Despite recent rapid advances in polymer science, the synthesis of fine polymers containing disulfide backbones is very limited, probably due to the vulnerability of disulfide bonds under most polymerization conditions. Oxidative coupling of disulfhydryl monomers, condensation polymerization of disulfide-line-containing monomers and copolymerization of dihalide-containing monomers with sodium disulfide are representative strategies for poly(disulfide) synthesis. However, the step-growth polymerization method described above inevitably leads to polymers with a broad distribution (polydispersity index (PDI) > 2) of molecular weight. Chain-growth polymerization was attempted to obtain poly(disulfide)s with a narrower molecular weight distribution, but only limited improvements were possible. For example, ring-opening polymerization of strained disulfide monomers via thiol-disulfide exchange yielded mixtures of linear and cyclic polymers and even catenanes with still broad molecular weight distributions. The formation of these complex product mixtures can be attributed to the limited selectivity of thiol-disulfide exchange between the disulfide of the monomers and the polymer backbone. In order to solve this problem, various reaction conditions were tested and a linear polymer was obtained as the main product, but unwanted cyclic oligomers with PDI > 1.4 were still present. Ring-opening metathesis polymerization (ROMP), a thiol-disulfide exchange reaction and an orthogonal thiol-disulfide exchange reaction, have also been applied to the synthesis of poly(disulfide). However, undesired interactions between the ruthenium catalyst and the disulfide resulted in large PDI > 1.5 as well as failure of homopolymerization of the disulfide monomer. From the previous results, it was confirmed that it is important to select polymerization conditions in which unwanted thiol-disulfide exchange and catalyst-disulfide interactions are suppressed in order to obtain a fine poly(disulfide) with a narrow molecular weight distribution.

One object of the present invention is to provide a method for producing a polymer containing poly(disulfide), comprising the step of reacting an oxaditicycloalkanone-based monomer with a primary or secondary alcohol as an initiator in the presence of an organic catalyst. .

Another object of the present invention is to provide a polymer comprising a poly(disulfide) moiety in which ((hydroxyalkyl)disulfanyl)alkanoic acid is used as a repeating unit.

Another object of the present invention is to provide a nano or micro structure made of the above polymer.

Another object of the present invention is to provide a drug delivery system comprising the polymer and a drug loaded thereon.

As one aspect for achieving the object of the present invention, the present invention provides poly (disulfide), comprising the step of reacting a monomer represented by Formula 1 with a primary or secondary alcohol as an initiator in the presence of an organic catalyst Provided is a method for preparing a polymer comprising:

[Formula 1]

In Formula 1,

n and m are each independently a natural number from 1 to 3;

The oxaditicycloalkanone ring may be unsubstituted or substituted, and may be linked to adjacent carbon atoms to form an unsubstituted or substituted hydrocarbon or heterocycle.

For example, the monomer represented by Formula 1 may be a compound represented by Formula 1-1 below:

[Formula 1-1]

In Formula 1-1,

R ₁ to R ₄ are each independently hydrogen or C _1-4 alkyl;

n and m are as defined above.

For example, the organic catalyst may be an organic acid catalyst. Specifically, it may be diphenyl phosphate or bis(4-nitrophenyl)phosphate, but is not limited thereto.

For example, the monomer is 1,4,5-oxadithiepan-2-one (1,4,5-oxadithiepan-2-one; OTP) or 3-methyl-1,4,5-oxadithiepan- It may be 2-one (3-methyl-1,4,5-oxadithiepan-2-one; MeOTP), but is not limited thereto.

For example, the above monomers are produced by reacting C _1-3 mercaptoalkanol with C _2-4 mercaptoalkanoic acid, resulting in an oxidative cyclization reaction of C _1-3 mercaptoalkyl C _2-4 mercaptoalkanoate. It may be prepared through, but is not limited thereto.

For example, the primary or secondary alcohol used as an initiator in the production method of the present invention may be a small molecule or a polymer material. For example, C _6-10 aryl (hydroxy C _1-4 alkane), hydroxy C _1-6 alkyne, hydroxy C _1-6 alkene, hydroxy C _1-6 alkane, or polyethylene glycolyl having a terminal hydroxyl group. can Specifically, it may be benzyl alcohol, propargyl alcohol, 2-propanol, or polyethylene glycol containing a reactive hydroxy group at at least one terminal, but is not limited thereto. For example, a material including a reactive hydroxyl group, but not including a free amine group or thiol group, which is a highly reactive functional group, or a material containing an amine group or thiol group protected by Boc or the like may also be included without limitation.

Specifically, the molecular weight of the final polymer may be controlled by adjusting the type of initiator used and the molar ratio of the monomer to the initiator. For example, the molar ratio of the monomer to the initiator may be 10 to 1,000. Specifically, the molar ratio may be 10 to 500, more specifically 20 to 300, but is not limited thereto. Preferably, the molar ratio of the monomer to the initiator may be appropriately determined according to the target molecular weight of the polymer to be finally synthesized.

For example, in the production method of the present invention, it is possible to control not only the molecular weight of the finally produced polymer but also its distribution by controlling the reaction conditions such as the injection rate of the initiator. Preferably, the reaction conditions can be optimized to have a polydispersity index (PDI) of less than 1.1 in terms of molecular weight, more preferably to have a polydispersity index close to 1.

In another aspect, the present invention provides a polymer comprising a poly(disulfide) moiety represented by Formula 2 below:

[Formula 2]

In the additive Formula 2,

R is C _6-10 aryl (C _1-4 alkyl), C _1-6 alkynyl, C _1-6 alkenyl, C _1-6 alkyl, or polyethylene glycol having a molecular weight of 300 to 30,000;

n and m are each a natural number of 1 to 3;

p is a natural number from 10 to 1000;

Carbons in the repeating unit may be unsubstituted or substituted, and may be linked to adjacent carbons to form unsubstituted or substituted hydrocarbons or heterocycles.

For example, the polymer may be a polymer containing a poly(disulfide) moiety represented by Chemical Formula 2-1, but is not limited thereto:

[Formula 2]

In the additive formula 2-1,

R ₁ to R ₄ are each independently hydrogen or C _1-4 alkyl;

R, n, m, and p are as defined above.

For example, the polymer of the present invention may be prepared by the method described above, but is not limited thereto.

For example, the polymers of the present invention may be degraded by physical stimuli, chemical stimuli, or both.

As another aspect, the present invention provides a nano or micro structure made of the above polymer.

Furthermore, the present invention provides a drug delivery system including the polymer and a drug loaded thereon.

As noted above, the polymers of the present invention may degrade in response to physical and/or chemical stimuli. Therefore, since it can be prepared to be degraded under specific conditions in the body, it can be used as a drug delivery system by carrying a drug thereon.

Specifically, the polymer of the present invention can release a drug by decomposition in response to glutathione. Since glutathione is a substance showing a relatively high concentration in cancer tissue and cytoplasm, for example, when preparing the poly(disulfide) polymer of the present invention, a polymeric alcohol containing a hydroxyl group at at least one end of polyethylene glycol, a hydrophilic polymer, is used as an initiator. In this case, an amphiphilic polymer in which a polyethylene glycol unit and a poly(disulfide) unit coexist can be provided, which can form nano and/or micro structures such as polymersomes and lamellar structures through self-assembly. At this time, since the polymersome is advantageous for carrying hydrophobic molecules, it can be used as a drug delivery system. For example, a drug delivery system prepared by carrying an anticancer drug in the polymersome can be selectively degraded in cancer tissue by the glutathione-sensitive degradability of the polymer to release the drug, so it can be usefully used as a drug delivery system for an anticancer drug. However, this is only one example and the use of the drug delivery system of the present invention is not limited thereto.

In addition, the polymer of the present invention forms a copolymer when prepared by reacting with a polymeric alcohol as an initiator, which can form a nanostructure through a process such as self-assembly according to the nature of the unit polymer constituting it, Since only the poly(disulfide) polymer portion can be selectively decomposed and removed by one degradability, it can be used for the preparation of porous nano/microstructures. At this time, the pore size and/or porosity of the porous nano/micro structure obtained by selectively decomposing poly(disulfide) can be controlled by adjusting the molecular weight of the polymeric alcohol used as the initiator and/or the ratio of the monomer to the initiator. there is. The porous nano/micro structure prepared in this way can be applied to various industrial fields besides the drug delivery system described above.

This invention is the first reported example of the controlled polymerization of a poly(disulfide) with a narrow molecular weight distribution. Using a diphenylphosphate (DPP) catalyzed lactone ring-opening polymerization method, a disulfide-containing seven-membered ring lactone, 1,4,5-oxadithiepan-2-one (1,4,5- oxadithiepan-2-one; OTP) was polymerized. Polymerization proceeded in a living manner, and the resulting polymer exhibited a very narrow polydispersity index (PDI) value of less than 1.1 and excellent backbone degradability in response to reducing conditions and UV irradiation. was

1 is a diagram schematically showing a polymerization process of poly(disulfide) according to the present invention.
2 is a diagram showing SEC chromatograms of P1 to P5 .
3 is a diagram showing the results of MALDI-MS analysis of P2 .
4 is a diagram showing the SEC chromatogram of P6 (Target [M]/[I] = 50).
5 is a diagram showing the SEC chromatogram of P7 (Target [M]/[I] = 50).
6 is a diagram showing the SEC chromatogram of P8 (Target [M]/[I] = 50).
7 is a diagram showing the SEC chromatogram of P9 (Target [M]/[I] = 80).
8 is a diagram showing the molecular weight change according to the controlled ring-opening polymerization of OTP. (a) shows the M _n and PDI plot of poly(OTP) against conversion, [OTP]/[BnOH] = 40, M _n and PDI were determined by SEC (chloroform as eluent, PS as standard) . Conversion was determined by ¹ H NMR. (b) shows the reaction time -ln ([M]/[M] ₀ ) plot, where [M]/[M] ₀ was determined by ¹ H NMR. (c) shows the SEC chromatogram of poly(OTP) that changes with reaction time.
9 is a diagram showing the molecular weight change according to the continuous one-pot post-polymerization of OTP. (a) shows the SEC chromatogram of poly(OTP) by one-pot post-polymerization. 1st feed ([OTP]/[BnOH] = 25) and 2nd feed ([OTP]/[BnOH] = 25). (b) shows the SEC chromatograms of poly(εCL) and poly(εCL) -b -poly(OTP) by one-pot post-polymerization. 1st feed ([εCL]/[BnOH] = 30) and 2nd feed ([OTP]/[BnOH] = 30). The black and red curves represent the molecular weight distributions of polymers obtained from polymerization with primary feed only and with primary and secondary feeds, respectively.
Figure 10 shows the stimulus (Stimuli) -responsive (responsive) decomposition of poly (OTP)s It is also (a) shows the change of the SEC chromatogram of poly(OTP) ( P3 ) before and after DTT treatment (1 eq. of disulfide bond in P3 ). (b) shows the change of the SEC chromatogram of poly(OTP) ( P2 ) before and after UV irradiation (5 W cm ^-2 ).
11 is a diagram showing the results of MALDI-MS analysis of OTP. Green represents peaks from matrix only (dithranol/sodium trifluoroacetate), red represents peaks from matrix and OTP. Calculated for C ₄ H ₆ Na O ₂ S ₂ [M+Na] ⁺ : 173.20, found: 173.20.
12 is a diagram showing a time-dependent NMR spectrum during a kinetics experiment.
13 is a diagram showing the results of TGA analysis of P5 .
14 is a diagram showing the NMR spectrum of P3 after DTT treatment.
Figure 15 is 2-mercaptoethyl 2-mercaptoacetate ¹ H NMR spectrum (500 MHz, CDCl ₃ )
16 is 1,4,5-oxadithiepan-2-one (OTP) ¹ H NMR spectrum (500 MHz, CDCl ₃ )
17 is a typical homopolymer initiated by BnOH, P2. ¹ H NMR spectrum (500 MHz, CDCl ₃ ) It is a diagram showing.
18 is of P6 ¹ H NMR spectrum (500 MHz, CDCl ₃ ) It is a diagram showing.
19 is of P7 ¹ H NMR spectrum (500 MHz, CDCl ₃ ) It is a diagram showing.
20 is mPEO- b -poly(OTP) ¹ H NMR, 500 MHz spectrum (CDCl ₃ ) It is a diagram showing.
21 is a poly(εCL) -b -poly(OTP) ¹ H NMR spectrum (500 MHz, CDCl ₃ ) It is a diagram showing.
22 is an OTP It is a diagram showing a ¹³ C NMR spectrum (125 MHz, CDCl ₃ ).
23 is a poly(OTP) It is a diagram showing a ¹³ C NMR spectrum (125 MHz, CDCl ₃ ).
24 is a diagram showing the ¹ H- ¹ H COZY spectrum of 1,4,5-oxadithiepan-2-one (OTP).
25 is a diagram showing a ¹ H- ¹ H COZY spectrum of poly(OTP).
26 is a diagram showing the ¹ H NMR spectrum (500 MHz, CDCl ₃ ) of 2-mercaptoethyl 2-mercaptopropanoate.
27 is a diagram showing a ¹ H NMR spectrum (500 MHz, CDCl ₃ ) of 3-methyl-1,4,5-oxadithiepan-2-one (MeOTP).
28 is a diagram showing a ¹ H NMR spectrum (500 MHz, CDCl ₃ ) of poly(MeOTP).
29 is a diagram showing an SEC chromatogram of poly(MeOTP) (CHCl ₃ eluent, 0.7 ml/min, calibrated with a polystyrene standard, M _n =7.50 kDa Mw=7.98 kDa, PDI=1.06).

Hereinafter, the present invention will be described in more detail by the following examples. However, the following examples are only for exemplifying the present invention, and the scope of the present invention is not limited only to these.

Example 1: Materials and Experimental Methods

¹ H-NMR spectra were recorded on a Varian spectrometer (500 MHz). ¹ H chemical shifts were referenced from the chemical shifts of tetramethylsilane (0.00 ppm). ¹³ C-NMR spectra were recorded on a Varian (125 MHz) spectrometer with complete proton decoupling. ^{The 13} C chemical shift was referenced to the chemical shift of CDCl ₃ (77.16 ppm). Two-dimensional (2D) NMR spectra of monomers and polymers were recorded on a Varian (500 MHz) spectrometer. NMR spectra by performing 2D ¹ H- ¹ H homonuclear and ¹ H- ¹³ C heteronuclear experiments [2D correlated spectroscopy (COSY) and heteronuclear single quantum coherence (HSQC)] has been signed. MALDI-MS spectra were recorded on Bruker Daltonics Microflex LT and Bruker Daltonics UltrafleXtreme TOF/TOF using dithranol as matrix and sodium trifluoroacetate as cation source. UV light was generated from an Inno-cure 150 with a 357 nm-filter attached. ATR-FTIR spectra were recorded on a Thermo Scientific NICOLET iS10 spectrometer. For long-time reagent infusion, an LSP02-1B syringe pump was used. Size exclusion chromatography (SEC) was performed on a Young Lin YL9100 GPC system equipped with a Shodex GPC column [K-803 (for chloroform) or KF-803 (for tetrahydrofuran)]. Samples were diluted to 1-5 mg/ml in the mobile phase before injection into the SEC system and filtered through a 0.20 μm-PTFE filter. Thermogravimetric analysis (TGA) was performed at a scan rate of 10° C./min under N ₂ gas using a TA Instruments Q50 model device. 2-mercaptoethanol, 2-thioglycolic acid, 2-mercaptopropionic acid, p-toluenesulfonic acid monohydrate; p -TsOH), diphenylphosphate (DPP), ε-caprolactone (εCL), benzyl alcohol (BnOH), propargyl alcohol, 2-propanol (2 -propanol), poly(ethylene oxide) methyl ether ( M _n ~2000), D , L-dithiothreitol (DTT) , dithranol , chloroform, sodium iodide and 4Å molecular sieves from Sigma Aldrich, poly(ethylene oxide) methyl ether ( M _n ~1000) from TCI (Japan). 1,3,5-trimethoxybenzene is from Alfa Aesar (USA), pyridine, magnesium sulfate, sodium thiosulfate, hydrogen peroxide peroxide, 30.0-35.5% aqueous solution), ethyl acetate, methanol, dichloromethane, diethylether, chloroform (HPLC grade), tetrahydrofuran (HPLC grade) ) was purchased from Samchun Chemicals (Korea). Alcohol and ε-caprolactone were purchased in anhydrous form or distilled under calcium hydride prior to use.

Example 2: Synthesis of poly(disulfide) and copolymers containing the same

A. Synthesis of oxaditicycloalkanone monomers

Two oxadithiocycloalkanone monomers, 1,4,5-oxadithiepan-2-one (OTP) and 3-methyl-1,4,5-oxadithiepan-2-one were obtained through two steps. (MeOTP) was synthesized.

Step 1-1. Synthesis of 2-mercaptoethyl 2-mercaptoacetate

In 2-mercaptoethanol (1.00 ml, 14.2 mmol), 1.19 ml of 2-thioglycolic acid (2-thioglycolic acid, 17.0 mmol, 1.20 equiv.) and 135 mg of p -toluenesulfonic acid ( p -toluenesulfonic acid, 0.710 mmol, 0.05 equiv.) was added. The reaction mixture was sealed and stirred at 50 °C for 3 days. The crude mixture was dissolved in 20 ml of chloroform, washed three times with 100 ml of an aqueous sodium bicarbonate solution (distilled water: saturated NaHCO ₃ aqueous solution = 9:1), and then washed three times with 100 ml of distilled water. The obtained organic layer was dried over anhydrous MgSO ₄ , filtered and concentrated under reduced pressure. Thereafter, 10 ml of dichloromethane was added and concentrated under reduced pressure to evaporate excess chloroform. The product was used in the subsequent reaction as a pale yellow liquid without further purification (1.40 g, 65%).

¹ H NMR (500 Mz, CDCl ₃ ) δ 4.27 (t, 2H), 3.29 (d, 2H) 2.78 (t, 2H) 2.03 (t, 1H) 1.53 (t, 1H)

Step 1-2. Synthesis of 2-mercaptoethyl 2-mercaptopropanoate

Except for using the same equivalent of 2-mercaptopropanoic acid instead of 2-thioglycolic acid, it was reacted in the same way as in Step 1-1. to obtain a yellow liquid product, which was used in subsequent reactions without additional purification. (1.35 g, 57%).

¹ H NMR (500 Mz, CDCl ₃ ) δ 4.27 (m, 2H), 3.53 (m, 1H), 2.79 (q, 2H) 2.18 (d, 1H) 1.55 (t, 1H), 1.54 (d, 3H)

Step 2-1. Catalytic oxidative cyclization of mercaptoethyl-2-mercaptoacetate

To 250 ml of ethyl acetate, sodium iodide (1.87 mg, 12.5 μmol) and 0.25 ml of hydrogen peroxide solution (30.0-35.5% aqueous solution) were added. The mixture was vigorously stirred until the color of the solution turned yellow. 190 mg of the product from step 1-1 above was dissolved in 25 ml of ethyl acetate and injected into the sodium iodide mixture by syringe pump at 70 ^° C. for 10 hours. After completely injecting the solution, the reaction mixture was cooled to room temperature and washed once with 200 ml of 10% sodium thiosulfate aqueous solution and twice with 250 ml of distilled water. The obtained organic layer was dried over anhydrous MgSO ₄ , filtered and concentrated under reduced pressure. The obtained crude oil was purified by flash column chromatography on silica gel (ethyl acetate : n -hexane = 6 : 1) to yield the title compound 1,4,5-oxadithiepan-2-one as a pale yellow oil (114 mg, 60%) was obtained.

¹ H NMR (500 Mz, CDCl ₃ ) δ 4.66 (t, 2H), 3.93 (s, 2H), 3.09 (br, 2H)

¹³ C NMR (125 Mz, CDCl ₃ ) δ 169.11, 69.25, 41.99, 36.75

FTIR (ATR) 3448, 2957, 1729, 1303, 1240, 1099, 1061, 1013, 774, 630, 561, 496, 454, 410 cm ^-1

MS (MALDI-MS) calculated for C ₄ H ₆ Na O ₂ S ₂ [M+Na] ⁺ : 173.20, found: 173.20

elemental analysis found: C, 32.22; H, 4.11; S, 43.66; O, 21.16. Calc. for C ₄ H ₆ S ₂ O ₂ : C, 31.98; H, 4.03; S, 42.69; O, 21.30%

Step 2-2. Catalyzed oxidative cyclization of mercaptoethyl-2-mercaptopropanoate

A crude oil was obtained by flash column chromatography on silica gel by reacting in a similar manner to Step 2-1, except that the product from Step 1-2 (210 mg) was used instead of the product from Step 1-1. Purification by chromatography (ethyl acetate : n-hexane = 8 : 1) gave the title compound 3-methyl-1,4,5-oxadithiepan-2-one as a pale yellow oil (106 mg, 52%). .

¹ H NMR (500 Mz, CDCl ₃ ) δ 4.68 (m, 1H), 4.51 (m, 1H), 4.18 (b, 1H), 3.00 (b, 2H) 1.55 (d, 3H)

B. General process for homopolymerization of OTP or MeOTP (P1-P7)

OTP (300 mg, 2 mmol) or MeOTP (328 mg, 2 mmol) was dissolved in 1.7 ml of anhydrous chloroform in a glove box. 4Å molecular sieve was added to the solution and stored for 2 days at 15-17° C. under an argon atmosphere. The concentration of the monomer solution was calibrated by ¹ H NMR spectroscopy using 1,3,5-trimethoxybenzene as an internal standard. Diphenyl phosphate (DPP) and various initiators (alcohols) were individually dissolved in anhydrous chloroform to prepare 0.1 M stock solutions. 0.1 ml of the initiator stock solution was added to the desired amount of OTP according to the desired [M]/[I] ratio. After stirring the reaction mixture for 2 minutes, 0.1 ml of DPP stock solution was rapidly injected. A small portion was aliquoted from the reaction mixture to determine the progress of the polymerization reaction. Aliquots were immediately quenched with excess pyridine. The reaction mixture was also quenched with excess (> 5 equiv.) of pyridine and precipitated with cold methanol. The precipitate was recovered by centrifugation at 2500 rpm and dried in vacuo to give a white greasy solid regardless of the initial [M]/[I]. The dried polymer was stored at -20 °C.

C. General process for block-copolymerization using mPEO as macroinitiator (P8 and P9)

OTP and DPP solutions were prepared in the same manner as in the single polymerization. mPEO was dissolved in anhydrous chloroform and dried for 3 days with a 4Å molecular sieve. The mPEO solution was calibrated with ¹ H NMR spectrum using 1,3,5-trimethoxybenzene as an internal standard and used as a stock solution. 0.01 mmol of mPEO chloroform solution was added to the monomer solution and the mixture was stirred for 2 minutes. Then, 0.1 ml of DPP solution was rapidly injected. The reaction was quenched in the same way as in the single polymerization. The polymer was precipitated with cold diethyl ether. The precipitate was recovered by centrifugation at 2500 rpm and dried in vacuo to give a white oily solid. The dried polymer was stored at -20 °C.

- Representative polymers synthesized from different initiators ^One H, ¹³ C NMR characterization

In P2 , ¹ H NMR analysis, I = BnOH, [OTP]/[I] = 40

¹ H NMR (500 Mz, CDCl ₃ ) δ 7.42-7.32 (m, 5H), 5.19 (s, 2H), 4.44 (t, 76H), 4.37 (t, 2H), 3.89 (t, 2H), 3.55(s) , 76H), 3.53 (s, 2H), 3.51 (t, 2H), 3.04 (t, 76H), 2.96-2.94 (m, 4H)

In P6 , ¹ H NMR analysis, I = Propargyl alcohol, [OTP]/[I] = 51

¹ H NMR (500 Mz, CDCl ₃ ) δ 4.77(d, 2H), 4.44 (t, 104H), 3.89 (t, 2H), 3.55(s, 104H), 3.53(s, 2H), 3.04 (t, 104H) ), 2.96 (t, 2H), 2.55 (t, 1H)

In P7 , ¹ H NMR analysis, I = 2-Propanol, [OTP]/[I] = 55

¹ H NMR (500 Mz, CDCl ₃ ) δ 5.06(m, 1H), 4.44 (t, 108H), 3.89 (t, 2H), 3.55(s, 108H), 3.53(s, 2H), 3.04 (t, 108H) ), 2.96 (t, 2H), 1.28 (d, 6H)

In P8, ¹ H NMR analysis, I = mPEO-OH (1 kDa), [OTP]/[I] = 49.5

¹ H NMR (500 Mz, CDCl ₃ ) δ 4.44 (t, 97H), 4.31 (t, 2H), 3.89 (t, 2H), 3.73 (t, 2H), 3.64 (s, 86H), 3.55 (s, 97H) ), 3.53(s, 2H), 3.38(s, 3H), 3.04 (t, 97H), 2.96 (t, 2H)

- from the polymer backbone ¹³ C NMR peak

¹³ C NMR (125 Mz, CDCl ₃ ) δ 169.23, 63.31, 41.45, 36.70

- FTIR and elemental analysis of P2

FTIR (ATR) 3450, 2949, 1728, 1264, 1143, 1120, 990, 767, 696, 576, 466, 435, 404 cm ^-1

elemental analysis found: C, 32.04; H, 4.05; S, 42.13; O 20.94. Calc. for C ₁₆₇ H ₂₄₇ S ₈₀ O ₈₁ : C, 32.80; H, 4.07; S, 41.94; O,21.19%

D. Poly(εCL)- b -Synthesis process of poly (OTP) (Target BnOH: εCL: OTP = 1: 30: 30)

OTP, DPP and BnOH solutions were prepared in the same manner as in the single polymerization. εCL was prepared as a 1 M stock solution by dissolving it in chloroform. To 0.3 ml of εCL solution, 0.1 ml of BnOH solution was added. The mixture was stirred for 2 minutes and 0.1 ml of DPP solution was rapidly injected. After confirming complete conversion of εCL by ¹ H NMR spectrum, 30 equivalents of OTP solution to BnOH were rapidly injected into the mixture. The reaction was terminated in the same manner as in the single polymerization. The polymer was precipitated with cold methanol. The precipitate was recovered by centrifugation at 2500 rpm and dried in vacuo to give a white oily solid. The dried polymer was stored at -20 ^° C.

- polymeric ^One H NMR characterization

In ¹ H NMR analysis, I = BnOH, [BnOH] : [εCL] : [OTP] = 1 : 33.5 : 35

¹ H NMR (500 Mz, CDCl ₃ ) δ 7.42-7.32 (m, 5H), 5.19 (s, 2H), 4.44 (t, 68H), 4.15 (t, 2H), 4.06 (t, 65H) 3.89 (t, 2H), 3.55 (s, 68H), 3.53 (s, 2H), 3.04 (t, 68H), 2.96 (t, 2H), 2.37 (t, 2H), 2.31 (t, 65H), 1.65 (m, 134H) ) 1.38 (m, 67H)

E. Degradation test of poly(OTP) by D,L-Dithiothreitol (DTT)

To a solution of P3 (7.5 mg) in chloroform (1 ml, HPLC grade) was added 7.7 mg of DTT. The solution was stirred at room temperature for 24 hours and analyzed by SEC without further purification.

Specifically, the P3 chloroform solution was treated with 1 equivalent (equiv.) of DTT and left under open conditions for 14 days. The resulting white crude sticky solid was washed with CDCl ₃ and ^{a 1} H NMR spectrum was acquired. The resulting 2-mercaptoethyl 2-mercaptoacetate from thiol-disulfide exchange was observed in the spectrum.

F. Degradation Test of Poly(OTP) Under UV Irradiation

7.5 mg of P4 was dissolved in chloroform (1 ml, HPLC grade). The P4 solution was irradiated with UV light (λ _max = 357 nm, 5 W cm ^-1 ) under open conditions. At each time point, the solution was analyzed by SEC without further purification.

<Results and Discussion>

In this study, lactone polymerization was chosen for the synthesis of poly(lactone), as many catalysts for controlled polymerization of poly(lactone) have already been established. As a monomer, 1,4,5-oxadithiepan-2-one (1,4,5-1,4,5- oxadithiepan-2-one; OTP) was designed. We reasoned that the 7-membered ring structure could provide sufficient ring strain for polymerization (FIG. 1). OTP was prepared from the catalytic intramolecular oxidation of an α,ω-disulfhydryl ester formed from 2-mercaptoethanol and 2-thioglyconic acid. A variety of catalysts ranging from bases to Lewis and Bronsted acids have been screened for OTP polymerization, but the catalysts enhance the electrophilicity of the disulfide or the nucleophile of the nucleophile, thereby inducing unwanted nucleophilic attack on the disulfide. Therefore, the disulfide bond was vulnerable under most reaction conditions. Among these, diphenylphosphate (DPP), a Bronsted acid with a p K _a of 3.88 in DMSO, exhibited remarkable tolerance to disulfide, while exhibiting strong catalytic activity for the polymerization of OTP. Therefore, DPP was used as a catalyst in all polymerization reactions below.

Polymerization of OTP was carried out using catalytic DPP and benzyl alcohol (BnOH) as initiator (I) at various [OTP]/[I] ratios ([OTP]/[I] = from 20 to 180) did The general procedure of the polymerization is described in more detail below. In the present invention, considering the solubility of the OTP polymer having a high sulfur content of about 43% (w/w), chloroform was selected as the reaction solvent. The molecular weight distribution was confirmed by size exclusion chromatography (SEC) (Table 1 and FIG. 2). Surprisingly, the polymers ( P1 to P5 ) were found to have a very narrow molecular weight distribution (PDI < 1.1) over a wide range of monomer to initiator (M) ratios. The PDI value of poly(OTP) was also smaller than that of poly(εCL) or poly(δ-valerolactone) previously reported using the same catalyst. The M _n values from the SEC analysis were in good agreement with the target M _n . In addition, the fidelity of the terminal benzyl group was confirmed by MALDI-MS (FIG. 3).

sample initiator Target [M]/[I] hour Conversion rate (%) ^a Mn _,Target (kDa) Mn _,SEC (kDa) PDI P1 BnOH 20 18 >99 3.11 ^{3.08b 1.07b} P2 BnOH 40 24 >99 6.12 ^{5.71b 1.05b} P3 BnOH 80 48 >99 12.1 ^{11.2b 1.05b} P4 BnOH 120 72 >99 18.1 ^{17.0b 1.04b} P5 BnOH 180 96 99 21.7 ^{22.6b 1.03b} P6 propargyl alcohol 50 32 >99 7.57 ^{7.82b 1.05b} P7 2-Propanol 50 32 >99 7.57 ^{8.79b 1.05b} P8 m-PEO-OH (1 kDa) 50 32 >99 8.51 ^{9.22c 1.05c} P9 m-PEO-OH (2 kDa) 80 48 >99 14.0 ^{13.1c 1.04c}

a: Determined by ¹ H NMR spectrum.

b: determined by size exclusion chromatography (SEC), using chloroform as eluent, calibrated with polystyrene (PS) standards.

c: determined by SEC, using tetrahydrofuran as eluent, calibrated with PS standard.

In order to broaden the applicability of this method, various alcohols were tested as initiators. Propargyl alcohol also prepared poly(OTP) ( P6 ) with the desired molecular weight and narrow PDI (FIG. 4), which gives access to future end group functionalization via the alkyne-azide click reaction. It provides access to future terminal functionalization via azide click reaction. Next, despite the fact that secondary alcohols are generally considered unsuitable for fast initiation, a narrow molecular weight distribution could still be obtained when 2-propanol was used as an initiator ( P7 , PDI = 1.05) (FIG. 5). The initiation rate of OTP, despite being a secondary alcohol, was significantly higher than that of propagation rats, leading to the low PDI. Furthermore, ω-methoxy-capped polyethylene oxide (mPEO) has also been used as a macroinitiator for the synthesis of block copolymers. The polymerization gave mPEO- b -poly(OTP) with a narrow molecular weight distribution ( P8 and P9 ) (FIGS. 6 and 7). Such well-defined amphiphilic block copolymers with narrow molecular weight distributions could form controllable polymeric nanostructures with disulfide-based responsiveness for future applications.

Then, it was confirmed whether OTP was polymerized in a living/controlled manner. The polymerization kinetics of poly(OTP) were measured by ¹ H NMR and SEC (FIG. 8). As the reaction proceeded, a linear relationship between M _n versus conversion ratio and decrease in PDI ( M _w / M _n ) was confirmed. In addition, by plotting −ln ([M]/[M] ₀ ) versus reaction time, a strict linear relationship was obtained indicating that the polymerization rate is linearly proportional to the OTP concentration.

Furthermore, in order to verify the livingness of the terminal functional groups of the polymer, one-pot post-polymerization was performed with an additional OTP feed. First, while polymerization was performed at a [M]/[I] ratio of 25 for 24 hours, full conversion of the monomers was confirmed by ¹ H NMR. The solution was further stirred for another 24 hours without termination. There was no sign of backbiting or peak broadening in the SEC chromatogram even after 24 hours from monomer depletion (FIG. 9A, black curve). Then, a secondary monomer solution feed ([M]/[I] = 25) was added to the unquenched polymer solution, and the mixture was stirred for an additional 48 hours. Second full consumption of monomers was confirmed by ¹ H NMR. The SEC chromatogram clearly showed an almost 2-fold increased peak shift of M _n from 3.63 kDa to 6.56 kDa (Fig. 9a, red curve) as well as maintenance of a low PDI < 1.05, indicating that the chain ends of poly(OTP) were still " It means "living".

The above results made it possible to attempt continuous ring-opening polymerization of εCL and OTP in a one-pot manner for the preparation of poly(εCL) -b -poly(OTP). After the primary polymerization of the poly(εCL) block, while confirming the complete conversion of εCL by ¹ H NMR at a [εCL]/[I] ratio of 30 for 24 hours, the secondary OTP monomer was prepared at a [OTP]/[I] ratio of 30 It was injected rapidly at the rate [I]. After secondary polymerization for 48 hours, we could observe that the SEC peak shifted from the initial peak of poly(εCL), and M _n showed an increase of 4.5 kDa (Fig. 10b). Also, the PDI value remained below 1.09 during the continuous one-pot polymerization process. In addition, the peak corresponding to the methylene proton at the chain end (-C H ₂ OH) of poly(εCL) at 3.65 ppm is adjacent to the ester (-C H ₂ OOC-) in ^{the 1} H NMR spectrum after polymerization. shifted to 4.15 ppm corresponding to that of poly(εCL), indicating successful one-pot post-polymerization with OTP.

The disulfide backbone of poly(OTP) was expected to be degradable in response to various chemical and physical stimuli. As a representative chemical stimulus that induces disulfide metathesis in poly(OTP), reagents D,L-, which are well known to induce thiol-disulfide exchange reactions by forming stable intramolecular cyclic disulfides while reducing other disulfide substrates. Dithiothreitol (D,L-dithiothreitol; DTT) was selected. P3 ( M _n = 11.2 kDa) was dissolved in chloroform, and DTT was added to the solution in a molar ratio of 1:1 to the disulfide content of P3 . After incubation at room temperature for 24 hours, the backbone of poly(OTP) was almost completely decomposed into oligomers, as shown in the SEC chromatogram of FIG. 10a. The poly(OTP) exhibited characteristic degradability of disulfide polymers in response to reducing conditions. Subsequently, skeletal decomposition of poly(OTP) by UV irradiation, which is known to promote disulfide substitution by forming thiyl radicals through homolytic cleavage of disulfide, was confirmed. After irradiation with UV light (λ _max = 357 nm, 5 W cm ^-2 ), the retention time of the initial peak of P2 in SEC ( M _n = 5.71 kDa) increased, while small peaks appeared with increased intensity in the oligomer region ( Figure 10b). These results clearly showed the UV-responsive degradability of the poly(OTP) backbone.

<Conclusion>

So far, polydisulfide chemistry has been difficult to apply to various molecules due to its wide molecular weight distribution, but by the present invention, poly(disulfide) with a narrow molecular weight distribution can be obtained, and by using it, smart materials with stimulus-sensitivity can be used in various fields. became available. In addition, since the nanostructure formed thereby can be used for polymer nanopatterning, it is expected that it can be used in various fields of electronics and semiconductor materials as well as biomedicine.

Claims (12)

A method for producing a polymer containing poly(disulfide), comprising reacting a monomer represented by Formula 1 with a primary or secondary alcohol as an initiator in the presence of an organic catalyst:
[Formula 1]

In Formula 1,
n and m are each independently a natural number from 1 to 3;
The oxaditicycloalkanone ring may be unsubstituted or substituted, and may be linked to adjacent carbon atoms to form an unsubstituted or substituted hydrocarbon or heterocycle.
According to claim 1,
The organic catalyst is an organic acid catalyst, a manufacturing method.
According to claim 1,
The monomer is 1,4,5-oxadithiepan-2-one (1,4,5-oxadithiepan-2-one; OTP) or 3-methyl-1,4,5-oxadithiepan-2- One (3-methyl-1,4,5-oxadithiepan-2-one; MeOTP), the manufacturing method.
According to claim 1,
The monomer,
Prepared through an oxidative cyclization reaction of C _1-3 mercaptoalkyl C _2-4 mercaptoalkanoate prepared by reacting C _1-3 mercaptoalkanol with C _2-4 mercaptoalkanoic acid. method.
According to claim 1,
The primary or secondary alcohol is C _6-10 aryl (hydroxy C _1-4 alkane), hydroxy C _1-6 alkyne, hydroxy C _1-6 alkene, hydroxy C _1-6 alkane, or at least one Of polyethylene glycol containing a reactive hydroxyl group at the end of, the manufacturing method.
According to claim 1,
To control the molecular weight of the finally produced polymer by controlling the type of initiator used and the molar ratio of the monomer to the initiator, the manufacturing method.
A polymer comprising a poly(disulfide) moiety represented by Formula 2:
[Formula 2]

In the additive Formula 2,
R is C _6-10 aryl (C _1-4 alkyl), C _1-6 alkynyl, C _1-6 alkenyl, C _1-6 alkyl, or polyethylene glycol having a molecular weight of 300 to 30,000;
n and m are each a natural number of 1 to 3;
p is a natural number from 10 to 1000;
Carbons in the repeating unit may be unsubstituted or substituted, and may be linked to adjacent carbons to form unsubstituted or substituted hydrocarbons or heterocycles.
According to claim 7,
A polymer prepared by the method of any one of claims 1 to 6.
According to claim 7,
A polymer that is degraded by physical stimuli, chemical stimuli, or both.
A nano or microstructure made of the polymer of claim 7.
A drug delivery system comprising the polymer of claim 7 and a drug loaded thereon.
According to claim 11,
A drug delivery system that releases a drug by decomposition in response to glutathione.

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