Block copolymer containing photo-sensitive moiety

Abstract

A block copolymer and a use thereof are disclosed herein. The block copolymer of the present application may have excellent self-assembly properties or phase separation characteristics and simultaneously have characteristics capable of changing the self-assembly structure formed once, or provide a block copolymer capable of forming a pattern of phase separation structures in a polymer membrane.

Claims

1. A block copolymer comprising: a first polymer segment; a second polymer segment; and a third polymer segment, wherein the block copolymer has a star-like structure that the first to third polymer segments are covalently bonded to one connecting point while sharing the connecting point, a linker connecting at least one polymer segment of the three polymer segments to the connecting point is a cleavable linker, and wherein at least one of the first to third polymer segments comprises a vinylpyridine unit.

2. The block copolymer according to claim 1, wherein, in two polymer segments of the first to third polymer segments, 50% or more of monomer units are identical to each other and a difference of the same monomer in the corresponding segments is within 20 wt %, or a deviation of solubility parameter in each polymer segment is within 30%, and wherein the other polymer segment is different from the two polymer segments, and the polymer segment different from the two polymer segments comprises a vinylpyridine unit.

3. The block copolymer according to claim 2, wherein in the two polymer segments, 50% or more of monomer units are identical to each other and a difference of the same monomer in the corresponding segments is within 20 wt %.

4. The block copolymer according to claim 2, wherein in the two polymer segments, a deviation of solubility parameter in each polymer segment is within 30%.

5. The block copolymer according to claim 2, wherein any one of the two polymer segments is linked to the connecting point by the cleavable linker.

6. The block copolymer according to claim 1, wherein any one of the first to third polymer segments comprises a vinylpyridine unit and the other two segments comprise styrene units.

7. The block copolymer according to claim 1, wherein the cleavable linker comprises a 2-nitrobenzyl group, a coumarinyl group or a pyrenylalkyl group.

8. The block copolymer according to claim 1, wherein a number average molecular weight is in a range of 1,000 to 1,000,000.

9. The block copolymer according to claim 1, wherein a molecular weight distribution is in a range of 1.01 to 2.

10. A polymer membrane comprising the block copolymer of claim 1, wherein the block copolymer is self-assembled.

11. The polymer membrane according to claim 10, wherein two or more phase separation structures selected from the group consisting of sphere, cylinder, gyroid and lamella structures are simultaneously present.

12. The polymer membrane according to claim 10, wherein one segment of the first to third polymer segments in the block copolymer is mixed in the cleaved state with the block copolymer comprising the other two segments.

13. The polymer membrane according to claim 12, wherein the polymer segment in the cleaved state comprises a styrene unit.

14. A method for forming a polymer membrane comprising the block copolymer of claim 1 on a substrate, wherein the block copolymer is self-assembled, comprising implementing a first phase separation structure using the block copolymer of claim 1; and cleaving the cleavable linker of the block copolymer implementing the first phase separation structure, wherein a second phase separation structure different from the first phase separation structure is formed in the polymer membrane after the cleaving step.

15. The method for forming a polymer membrane according to claim 14, wherein the first phase separation structure comprises a sphere structure and the second phase separation structure comprises a cylinder structure.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 to 10 are analysis results for compounds or polymers produced in Preparation Examples.

(2) FIG. 11 is a GPC curve for a polymer (D) before and after ultraviolet irradiation in Example 1.

(3) FIG. 12 is a TEM image of a sample before ultraviolet irradiation for a polymer (D) of Example 2.

(4) FIG. 13 is a SAXS graph of a sample before ultraviolet irradiation for a polymer (D) of Example 2.

(5) FIG. 14 is a TEM image of a sample after ultraviolet irradiation for a polymer (D) of Example 2, where a small image at the upper left is a TEM image taken in a vertical direction.

(6) FIG. 15 is a SAXS graph of a sample after ultraviolet irradiation for a polymer (D) of Example 2.

(7) FIG. 16 is a cross-sectional AFM image of a thin membrane sample before ultraviolet irradiation for a polymer (D) in Example 3.

(8) FIG. 17 is a cross-sectional AFM image of a thin membrane sample after ultraviolet irradiation for a polymer (D) in Example 3.

(9) FIG. 18 is an SEM image that before ultraviolet irradiation for a polymer (D) in Example 4, a thin membrane sample has been transferred to metal nanoparticles.

(10) FIG. 19 is an SEM image that after ultraviolet irradiation for a polymer (D) in Example 4, a thin membrane sample has been transferred to metal nanowire.

MODE FOR INVENTION

(11) Hereinafter, the present application will be described in detail by way of examples, but the scope of the present application is not limited by the following examples.

(12) 1. NMR Measurement

(13) NMR analyses were performed at room temperature using an NMR spectrometer including a Varian Unity Inova (500 MHz) spectrometer with a triple resonance 5 mm probe. The analytes were diluted to a concentration of about 10 mg/ml in a solvent for NMR measurement (CDCl.sub.3), and chemical shifts were expressed in ppm.

(14) <Applied Abbreviation>

(15) br=broad signal, s=singlet, d=doublet, dd=double doublet, t=triplet, dt=double triplet, q=quartet, p=quintet, m=multiplet.

(16) 2. GPC (Gel Permeation Chromatograph)

(17) The number average molecular weight (Mn) and the molecular weight distribution were measured using GPC (gel permeation chromatography). Into a 5 mL vial, an analyte such as block copolymers of Examples or Comparative Examples or a giant initiator is put and diluted in THF (tetrahydrofuran) to be a concentration of about 1 mg/mL or so. Then, a standard sample for calibration and a sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm) and then measured. As the analytical program, ChemStation from Agilent Technologies was used, and the elution time of the sample was compared with the calibration curve to obtain the weight average molecular weight (Mw) and the number average molecular weight (Mn), respectively, and the molecular weight distribution (PDI) was calculated by the ratio (Mw/Mn) thereof. The measurement conditions of GPC are as follows.

(18) <GPC Measurement Condition>

(19) Instrument: 1200 series from Agilent Technologies

(20) Column: using two PLgel mixed B from Polymer Laboratories

(21) Solvent: THF

(22) Column temperature: 35° C.

(23) Sample concentration: 1 mg/mL, 200 uL injection

(24) Standard sample: polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

(25) Preparation Example 1

(26) A compound of Formula 1 below (5-(4-bromobutoxy)-2-nitrophenyl)methanol) was prepared in the following manner. 5 g (29.6 mmol) of 5-hydroxy-1-nitrobenzyl alcohol was dissolved in 200 mL of acetonitrile and then an aqueous solution of sodium hydride (2.16 g, 90 mmol) was added thereto while stirring at 0° C. The resulting yellow precipitate was filtered and dissolved in DMF (150 mL). After completely dissolving it, dibromobutane (7.03 g, 32.56 mmol) was slowly added at room temperature. After reaction for 12 hours, distilled water was poured to terminate the reaction and the reactant was extracted with ethyl acetate. The extract was purified by column chromatography to obtain the compound of Formula 1 below. The attached FIG. 1 is an analysis result for the compound.

(27) ##STR00001##

(28) <NMR Analysis Result>

(29) .sup.1H-NMR (400 MHz, CDCl.sub.3): d8.06 (d, 1H); d7.12 (s, 1H); d6.78 (d, 1H); d4.88 (s, 2H); d4.02 (t, 2H); d3.32 (t, 2H); d3.20 (s, 1H); d1.98 (p, 2H); d1.90 (p, 2H).

(30) Preparation Example 2

(31) A compound of Formula 2 below (5-(4-azidobutoxy)-2-nitrophenyl)methanol) was prepared in the following manner. The compound of Formula 1 (8.5 g, 27.9 mmol) in Preparation Example 1 and sodium azide (2.36 g, 36.3 mmol) were dissolved in a mixed solvent of acetone and distilled water (6:1) and refluxed at 65° C. in a nitrogen atmosphere to obtain a target product. The attached FIG. 2 is an analysis result for the compound.

(32) ##STR00002##

(33) <NMR Analysis Result>

(34) .sup.1H-NMR (400 MHz, CDCl.sub.3): d8.06 (d, 1H); d7.12 (s, 1H); d6.78 (d, 1H); d5.52 (s, 2H); d4.02 (t, 2H); d3.32 (t, 2H); d3.20 (s, 1H); d1.98 (p, 2H); d1.90 (p, 2H).

(35) Preparation Example 3

(36) A compound of Formula 3 below (5-(4-azidobutoxy)-2-nitrophenyl 2-bromo-2-methylpropanoate) was prepared in the following manner. The compound of Formula 2 (7.19 g, 27.0 mmol) in Preparation Example 2 was dissolved in THF (Tetrahydrofuran) and 2-bromo-2-methylpropanoyl bromide (7.45 g, 32.4 mmol) was added while stirring with triethylamine (3.24 g, 32.0 mmol) in a nitrogen atmosphere at 40° C. The salt generated during the reaction was filtered off and the residue was purified by column chromatography to obtain the compound of Formula 3 below. FIG. 3 is an analysis result for the compound.

(37) ##STR00003##

(38) <NMR Analysis Result>

(39) .sup.1H-NMR (400 MHz, CDCl.sub.3): d8.06 (d, 1H); d7.12 (s, 1H); d6.78 (d 1H); d5.52 (s, 2H); d4.02 (t, 2H); d3.32 (t, 2H); d1.99 (s, 6H); d1.98 (p, 2H); d1.90 (p, 2H).

(40) Preparation Example 4

(41) A compound of Formula 4 below (1-bromo-4-(1-phenylvinyl)benzene) was prepared in the following manner. Methyltriphenylphosphonium bromide (7.2 g, 20 mmol) and potassium tert-butoxide (2.3 g, 20 mmol) were put into THF (tetrahydrofuran) (50 mL), and THF (tetrahydrofuran) (35 mL) in which p-bromobenzophenone (3.4 g, 17 mmol) was dissolved was slowly added while stirring at room temperature, and the mixture was reacted for 3 hours. After reaction, a saturated aqueous solution of ammonium chloride was added to terminate the reaction and the reaction mixture was extracted with diethyl ether to obtain the compound of Formula 4 as a product. FIG. 4 is an analysis result for the compound.

(42) ##STR00004##

(43) <NMR Analysis Result>

(44) .sup.1H-NMRt (400 MHz, CDCl.sub.3): d7.33 (d, 2H); d7.19 (d, 5H); d7.05 (d, 2H); d5.32 (d, 2H).

(45) Preparation Example 5

(46) A compound of Formula 5 below (tert-butyldimethyl((4-(1-phenylvinyl)phenyl)ethynyl)silane) was prepared in the following manner. The compound of Formula 4 (3.89 g, 15 mmol) in Preparation Example 4 was completely dissolved in piperidine (50 mL) and then tert-butyldimethylsilylacetylene (2.53 g, 18 mmol) was added thereto. Then, the reaction was carried out at 50° C. for 24 hours, followed by filtering and extraction with hexane, and then the extract was purified by column chromatography to obtain the compound of Formula 5. FIG. 5 is an analysis result for the compound.

(47) ##STR00005##

(48) <NMR Analysis Result>

(49) .sup.1-NMR (400 MHz, CDCl.sub.3): d7.33 (d, 2H); d7.19 (d, 5H); d7.05 (d, 2H); d5.32 (d, 2H); d1.03(s, 9H); d0.22(d, 6H).

(50) Preparation Example 6

(51) A polymer (A) of Formula 6 below was synthesized. The compound of Formula 3 (50 mg) in Preparation Example 3 was used as an initiator, and a reaction solution in which styrene (6 mL), copper (I) bromide (18 mg) and PMDETA (N,N,N′,N″,N″-pentamethyldiethylenetriamine, 24 μL) were mixed was freeze-thawed three times and polymerized while stirring at 90° C. under a nitrogen atmosphere. The polymer solution was passed through an alumina column to remove the catalyst and precipitated in methanol to obtain a powder of the polymer (A). The polymer (A) had a number average molecular weight (Mn) of about 12,000 and a molecular weight distribution (Mw/Mn) of about 1.18. FIG. 6 shows the measurement result of the polymer (A).

(52) ##STR00006##

(53) Preparation Example 7

(54) A polymer (B) of Formula 7 below was synthesized. Lithium chloride (0.3 g) and THF (80 mL) were put into a reactor in an argon atmosphere and stirred at −78° C. so that they were sufficiently dissolved. Subsequently, 86 μL of a sec-butyl lithium solution at a concentration of 1.2 M was added and the purified styrene (3.0 g) was added thereto. After sufficiently stirring for about 1 hour, the compound of Formula 5 in Preparation Example 5 was added. Then, 2-vinylpyridine (2VP) (1.25 g) was added and stirred for about 1 hour or so, and then the reaction was terminated using 2-propanol to obtain the polymer (B). The polymer (B) had a number average molecular weight (Mn) of about 45000 and a molecular weight distribution (Mw/Mn) of about 1.20. Furthermore, the mass fraction of the polystyrene segment in the polymer (B) was about 72%. FIG. 7 is the GPC measurement result for the polymer (B).

(55) ##STR00007##

(56) Preparation Example 8

(57) A polymer (C) of Formula 8 below in which TBDMS as a protecting group was removed from the polymer (B) of Formula 7 above was synthesized. The polymer (B) of Preparation Example 7 was completely dissolved in THF and sufficiently degassed with nitrogen, and 10 mL of a solution of tetrabutylammonium fluoride (1.0 M in THF) was added thereto and stirred at room temperature for 12 hours. After reaction, THF was removed and the solvent was changed to chloroform, and the reactant was purified through column chromatography. As shown in FIG. 8, it was confirmed that the peak of d=0.2 corresponding to Si(CH.sub.3) contained in the protecting group in the polymer (B) disappeared through the above reaction.

(58) ##STR00008##

(59) Preparation Example 9

(60) The polymer (A) and the polymer (C) were coupled to synthesize a miktoarm block copolymer (polymer (D)) having three polymer segment arms. 0.1 g (1.2 eq.) of the polymer (A) and 0.25 g (1.0 eq) of the polymer (C) were sufficiently dissolved in 5 mL of THF and then degassed with nitrogen. After putting PMDETA (N,N,N′,N″,N″-pentamethyldiethylenetriamine, 24 mL) and copper (I) bromide (18 mg) into a reactor in sequence, the reactor was sealed and stirred at room temperature for 2 days, and then the remaining polymer (A) was removed through purification to obtain the polymer (D). The polymer (D) had a number average molecular weight (Mn) of about 60000 and a molecular weight distribution (Mw/Mn) of about 1.20. Furthermore, the mass fraction of the polystyrene segment in the polymer (D) was about 80%. FIG. 9 is the GPC measurement result for the polymer (D), and FIG. 10 is the results of comparing NMR before and after the reaction.

(61) ##STR00009##

(62) Example 1

(63) 10 mg of the polymer (D) was dissolved in THF (5 mL), coated on a glass substrate, and irradiated with ultraviolet rays having a wavelength of about 365 nm. It was confirmed that after irradiation of ultraviolet rays for 1 hour, the light split linker of the polymer (D) was decomposed and thus the polymer was completely decomposed into a derivative of the polymer (A) and a derivative of the polymer (C). Furthermore, as a result of analyzing the decomposed polymers by GPC, the peaks corresponding to the derivative of the polymer (A) and the derivative of the polymer (C) were confirmed (FIG. 11).

(64) Example 2

(65) 10 mg of the polymer (D) was dissolved in THF (5 mL) and subjected to solvent drop casting to prepare two samples, where one sample was not irradiated with ultraviolet rays and the other sample was irradiated with ultraviolet rays having a wavelength of about 365 nm. Subsequently, the two samples were each annealed at about 230° C. for 3 days or so and subjected to microtomy to prepare TEM (transmission electron microscopy) specimens, in which the TEM was confirmed using the specimens, and for the two samples, SAXS (small angle X-ray scattering) analysis was also performed. As a result of confirmation, the microphase separation structure of cylinder morphology was observed in the sample not irradiated with ultraviolet rays of the two samples. The results of the measurement results were shown in FIGS. 12 to 15.

(66) Example 3

(67) The polymer (D) was spin-coated on a silicon substrate to prepare a polymer thin membrane sample having a thickness of about 60 nm. Then, a part of the sample was not irradiated with ultraviolet rays and the other part was irradiated with ultraviolet rays having a wavelength of about 365 nm. Subsequently, the sample was annealed and observed by AFM (atomic force microscopy), and as a result, a sphere microphase separation structure was confirmed in the part not irradiated with ultraviolet rays, and a cylinder microphase separation structure horizontally oriented on the substrate was confirmed in the part irradiated with ultraviolet rays. The measurement results were shown in FIGS. 16 and 17.

(68) Example 4

(69) Trench structures were formed on a silicon wafer substrate in the following manner. A layer of SiO.sub.2 was formed on the substrate to a thickness of about 200 nm by a known deposition method. Subsequently, a BARC (bottom anti-reflective coating) was coated on the SiO.sub.2 layer to a thickness of about 60 nm and a PR (photoresist) layer (for KrF, positive-tone resist layer) was again coated thereon to a thickness of about 400 nm or so. Subsequently, the PR layer was patterned by a KrF stepper exposure method. Subsequently, the BARC layer and the SiO.sub.2 layer were etched using the patterned PR layer as a mask by an RIE (reactive ion etching) method, and the residues of the BARC layer and the PR layer were removed to form mesa structures. The spacing (D) between the mesa structures formed in this manner was about 150 nm, the height (H) was about 50 nm, and the width (W) of each mesa structure was about 150 nm.

(70) The polymer (D) was spin-coated on the mesa structures (trench structures) of the substrate formed in the above manner to prepare a polymer membrane sample having a thickness of about 60 nm or so. Subsequently, a part of the sample was not irradiated with ultraviolet rays and the other part was irradiated with ultraviolet rays having a wavelength of about 365 nm or so, and then annealed. The thin membrane with two microphases was immersed in an acid solution (HCl solution, 1%), in which the metal salt (Na2PtCL4) was dissolved, for 3 hours. Subsequently, by removing the polymer by O2 RIE and simultaneously reducing the metal salt, two nanostructures of platinum nanoparticles and platinum nanowires could be obtained. SEM (scanning electron microscopy) results for this were shown in FIGS. 18 and 19.