Polyimino thiazoline compound as well as synthesis method and application thereof

Abstract

The invention relates to the technical field of polymer chemistry, in particular to a poly (imino thiazoline) compound as well as a synthesis method and application thereof. According to the invention, elemental sulfur, an amine compound, an isonitrile compound, an organic solvent and an alpha-bromo-ketone compound are used as raw materials for in-situ construction of the polyimidothiazoline compound. The structures of the amine compound, the isonitrile compound and the alpha-bromo-ketone compound are adjustable, and the polyimidothiazoline compounds with different structures can be obtained along with the change of the monomer structures. The synthesis method does not involve a metal catalyst, has the characteristics of mild reaction conditions and simple process, and solves the problems of harsh reaction conditions, tedious steps, low reaction efficiency, non-specific product structure and the like in the heterocyclic polymer synthesis process through a multi-component tandem polymerization method.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer chemistry, and in particular, to a polyiminothiazoline compound, a synthesis method thereof, and an application thereof. Background Art

[0002] Sulfur-containing polymers are an important class of polymer materials. For example, polysulfides, polyphenylene sulfides, polythioureas, polythioamides, polydithiocarbamates, polythiocarbonates, polythiophenes, etc. have extensive applications in dynamic response, metal enrichment, self-healing materials, lithium-sulfur batteries, manufacturing industries, and the optical field. Among them, compared with sulfur-containing heterochain polymers, sulfur-containing heterocyclic polymers (such as polythiophene, polythiazole, etc.) usually have better chemical / thermal stability due to their unique structures and can be better applied in the field of optoelectronic materials.

[0003] However, the synthesis of sulfur-containing heterocyclic polymers is relatively difficult. For example, the synthesis of polythiophene often requires the coupling reaction of monomers containing thiophene rings under the catalysis of toxic metal catalysts. This synthesis method has problems such as harsh reaction conditions, cumbersome steps, low reaction efficiency, and unclear product structure, which to a certain extent hinder the development and application of polythiophene-based materials.

[0004] Currently, the synthesis of polythiazole still involves problems such as thiazole monomers, metal catalysts, toxic reagents, harsh reaction conditions, and many reaction steps (Polymer 2015, 68, 227e233; Polycycl. Aromat. Comp. 2022, 42, 3318 - 3327). Summary of the Invention

[0005] The purpose of the present invention is to provide a polyiminothiazoline compound, a synthesis method thereof, and an application thereof, and to prepare a polyiminothiazoline compound with simple process, mild conditions, and adjustable product structure.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] A synthesis method of a polyiminothiazoline compound, comprising the following steps:

[0008] Under a protective atmosphere, elemental sulfur, an amine compound, an isocyanide compound, and an organic solvent are mixed to undergo a first reaction to obtain a thiourea compound;

[0009] The thiourea compound is mixed with an α-bromo ketone compound to undergo a second reaction to obtain a polyiminothiazoline compound;

[0010] The amine compound includes a monofunctional aromatic amine, a bifunctional aliphatic amine, or a bifunctional aromatic amine;

[0011] The isocyanide compounds include bifunctional aliphatic isocyanide compounds, monofunctional aromatic isocyanide compounds or bifunctional aromatic isocyanide compounds;

[0012] The α-bromo ketone compounds include monofunctional α-bromo ketone compounds or bifunctional α-bromo ketone compounds.

[0013] Optionally, when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the molar ratio of the thiourea compound to the α-bromo ketone compound is 1-10:1-10;

[0014] Or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is 1-10:1-100;

[0015] Or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is 1-10:1-100;

[0016] Or when the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is 1-10:1-100.

[0017] Optionally, when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the first reaction further includes basic compounds;

[0018] Or when the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the first reaction further includes basic compounds.

[0019] Optionally, the monofunctional aromatic amine includes any one of the following structures:

[0020]

[0021] Wherein, R 1 、R 2 and R 3Independently, it is H, F, Cl, Br, I, hydroxyl group, mercapto group, trifluoromethyl group, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200;

[0022] The difunctional fatty amine includes any one of the following structures:

[0023]

[0024] wherein, m is an integer between 0 and 2000;

[0025] The difunctional aromatic amine includes any one of the following structures:

[0026]

[0027] m is an integer between 0 and 2000; R 4 is a hydrogen atom or an alkyl group with a carbon chain length of 1 to 200; X is CH2, O or S;

[0028] The molar ratio of the elemental sulfur to the amine compound is 2 to 20:1 to 5.

[0029] Optionally, the monofunctional aromatic isocyanide compound includes any one of the following structures:

[0030]

[0031] wherein, R 5 is H, F, Cl, Br, I, trifluoromethyl group, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200;

[0032] The difunctional fatty isocyanide compound includes any one of the following structures:

[0033]

[0034] wherein, m is an integer between 0 and 2000;

[0035] The difunctional aromatic isocyanide compound includes any one of the following structures:

[0036]

[0037] wherein, R 4 is a hydrogen atom or an alkyl group with a carbon chain length of 1 to 200; X is CH2, O or S; the molar ratio of the amine compound to the isocyanide compound is 1 to 10:2 to 5.

[0038] Optionally, the temperature of the first reaction is 25 to 120 °C, the time is 0.5 to 12 h, and the stirring rate is 100 to 900 rpm.

[0039] Optionally, the monofunctional α-bromo ketone compound includes any one of the following structures:

[0040]

[0041] wherein, R 6 or R 7 is independently H, F, Cl, Br, I, trifluoromethyl, phenyl, an alkyl group with a carbon chain length of 1-200, or an alkoxy group with a carbon chain length of 1-200; m is an integer between 0 and 2000;

[0042] The bifunctional α-bromo ketone compound includes any one of the following structures:

[0043]

[0044] wherein, m is an integer between 0 and 2000.

[0045] Optionally, the temperature of the second polymerization reaction is 25-120 °C, the time is 0.5-12 h, and the stirring rate is 100-900 rpm.

[0046] The present invention provides a polyiminothiazoline compound prepared by the above synthesis method.

[0047] The present invention also provides the application of the polyiminothiazoline compound in the field of high refractive index materials.

[0048] The present invention uses low-toxic, odorless, and economical elemental sulfur as a sulfur source, forms a thiourea intermediate with an amine compound and an isocyanide compound in a solvent, and then the thiourea intermediate undergoes a polymerization reaction with an α-bromo ketone compound to obtain a polyiminothiazoline compound.

[0049] Furthermore, when the amine compound is a monofunctional aromatic amine and the isocyanide compound is a bifunctional aliphatic isocyanide compound, a dithiourea compound is obtained from the raw materials under the catalysis of a base, and then reacts with a bifunctional α-bromo ketone compound to obtain a polyiminothiazoline compound with a thiazole ring in the main chain and an imino group in the side chain; when the amine compound is a bifunctional aliphatic amine and the isocyanide compound is a monofunctional aromatic isocyanide compound, a dithiourea compound can be efficiently obtained without adding a base, and then polymerizes with a bifunctional α-bromo ketone compound to obtain a polyiminothiazoline compound with a thiazole ring in the main chain and an imino group in the side chain; when the amine compound is a bifunctional aliphatic amine and the isocyanide compound is a bifunctional aromatic isocyanide compound, a polythiourea compound can be obtained without adding a base, and then polymerizes with a monofunctional α-bromo ketone compound to obtain a polyiminothiazoline compound with both a thiazole ring and an imino group in the main chain; when the amine compound is a bifunctional aromatic amine and the isocyanide compound is a bifunctional aliphatic isocyanide compound, a polythiourea compound is obtained from the raw materials under the catalysis of a base, and then polymerizes with a monofunctional α-bromo ketone compound to obtain a polyiminothiazoline compound with both a thiazole ring and an imino group in the main chain. The polyiminothiazolines synthesized by this method all have good thermal stability, good film-forming properties and relatively high refractive indices. In addition, the increase in the content of conjugated groups in the structure helps to increase the thermal stability of the material, and at the same time, is beneficial to improving the refractive index of the material.

[0050] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0051] The polymerization conditions of the present invention are mild, the process is simple, the atom utilization rate is high, the regioselectivity is good, and the structural controllability is extremely strong. The present invention uses inexpensive and readily available elemental sulfur as a sulfur source to in-situ construct sulfur-containing heteroaromatic polymers, without involving metal catalysts, and has the characteristics of economy and environmental protection.

[0052] The polyiminothiazoline compounds prepared by the present invention all have good thermal stability and processability, as well as good film-forming properties. The introduction of sulfur atoms and conjugated groups endows them with relatively high refractive indices, and they have potential application values in the fields of optics and optoelectronics. Description of the Drawings

[0053] Figure 1 It is a reaction equation diagram for preparing polyiminothiazoline compounds in Examples 1 to 3;

[0054] Figure 21H NMR and 13C NMR comparison charts of the polyiminothiazoline compound, its thiourea compound, and the corresponding model compound M9 prepared in Example 1 in deuterated DMSO; wherein, A is the 1H NMR chart of dithiourea compound I1, B is the 1H NMR chart of model compound M9, C is the 1H NMR chart of polyiminothiazoline compound P1, D is the 13C NMR chart of dithiourea compound I1, E is the 13C NMR chart of model compound M9, and F is the 13C NMR chart of polyiminothiazoline compound P1;

[0055] Figure 3 IR absorption spectra of raw material M4(A), dithiourea compound I1(B), corresponding model compound M9(C), and synthesized polyiminothiazoline compound P1(D) in Example 1;

[0056] Figure 4 1H NMR charts of the polyiminothiazoline compounds prepared in Examples 2-5 in deuterated DMSO;

[0057] Figure 5 13C NMR charts of the polyiminothiazoline compounds prepared in Examples 2 and 4-5 in deuterated DMSO;

[0058] Figure 6 TG analysis spectra of the polyiminothiazoline compounds prepared in Examples 1-2 and 4-5;

[0059] Figure 7 Refractive index spectra of the polyiminothiazoline compounds prepared in Examples 1 and 4-5;

[0060] Figure 8 TG analysis spectrum of the polyiminothiazoline compound prepared in Example 3. Detailed implementation mode

[0061] The present invention provides a method for synthesizing a polyiminothiazoline compound, comprising the following steps:

[0062] Under a protective atmosphere, elemental sulfur, an amine compound, an isocyanide compound, and an organic solvent are mixed to undergo a first reaction to obtain a thiourea compound;

[0063] The thiourea compound is mixed with an α-bromo ketone compound to undergo a second reaction to obtain a polyiminothiazoline compound;

[0064] The amine compound includes a monofunctional aromatic amine, a bifunctional aliphatic amine, or a bifunctional aromatic amine;

[0065] The isocyanide compounds include bifunctional aliphatic isocyanide compounds, monofunctional aromatic isocyanide compounds or bifunctional aromatic isocyanide compounds;

[0066] The α-bromo ketone compounds include monofunctional α-bromo ketone compounds or bifunctional α-bromo ketone compounds.

[0067] The amine compounds include monofunctional aromatic amines, bifunctional aliphatic amines or bifunctional aromatic amines;

[0068] The isocyanide compounds include bifunctional aliphatic isocyanide compounds, monofunctional aromatic isocyanide compounds or bifunctional aromatic isocyanide compounds;

[0069] The α-bromo ketone compounds include monofunctional α-bromo ketone compounds or bifunctional α-bromo ketone compounds.

[0070] In the present invention, the protective atmosphere is preferably at least one of nitrogen or noble gas, and more preferably nitrogen.

[0071] In the present invention, when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the molar ratio of the thiourea compound to the α-bromo ketone compound is preferably 1-10:1-100, more preferably 1-10:1-10;

[0072] Or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is preferably 1-10:1-100, more preferably 1-10:1-10, and even more preferably 5-7:7-8;

[0073] Or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is preferably 1-10:1-100, more preferably 1-10:1-10, and even more preferably 5-7:7-8;

[0074] Or when the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is preferably 1-10:1-100, more preferably 1-10:1-10, and even more preferably 5-7:7-8.

[0075] In the present invention, the amine compound is a monofunctional aromatic amine, the isocyanide compound is a difunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a difunctional α-bromo ketone compound. Preferably, the first reaction further comprises a base compound;

[0076] Or the amine compound is a difunctional aromatic amine, the isocyanide compound is a difunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound. Preferably, the first reaction further comprises a base compound.

[0077] In the present invention, the monofunctional aromatic amine preferably comprises any one of the following structures:

[0078]

[0079] Wherein, R 1 , R 2 and R 3 are independently preferably H, F, Cl, Br, I, hydroxyl group, mercapto group, trifluoromethyl group, alkyl group or alkoxy group; the monofunctional aromatic amine is further preferably aniline;

[0080] The difunctional aliphatic amine preferably comprises any one of the following structures:

[0081]

[0082] Wherein, m is preferably an integer between 0 and 2000, and further preferably between 5 and 200; the difunctional aliphatic amine is further preferably 1,6-hexanediamine;

[0083] The difunctional aromatic amine preferably comprises any one of the following structures:

[0084]

[0085] Wherein, m is preferably an integer between 0 and 2000, and further preferably between 1 and 500; R 4 is preferably a hydrogen atom or an alkyl group with a carbon chain length of 1 to 200, and further preferably an alkyl group with a carbon chain length of 5 to 10; X is preferably CH2, O or S;

[0086] The amine compound is further preferably aniline or 1,6-hexanediamine;

[0087] The molar ratio of the elemental sulfur to the amine compound is preferably 2 to 20:1 to 5, further preferably 3 to 10:1 to 4, and even more preferably 4 to 5:2 to 4.

[0088] In the present invention, the monofunctional aromatic isocyanide compound preferably comprises any one of the following structures:

[0089]

[0090] Among them, R 5 is preferably H, F, Cl, Br, I, trifluoromethyl, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200, and more preferably an alkyl group with a carbon chain length of 1 to 20 or an alkoxy group with a carbon chain length of 1 to 20;

[0091] The bifunctional aliphatic isocyanide compound preferably includes any one of the following structures:

[0092]

[0093] Among them, m is preferably an integer between 0 and 2000, and more preferably 10 to 500;

[0094] The bifunctional aromatic isocyanide compound preferably includes any one of the following structures:

[0095]

[0096] Among them, R 4 is preferably a hydrogen atom or an alkyl group with a carbon chain length of 1 to 200, and more preferably an alkyl group with a carbon chain length of 1 to 10; X is preferably CH2, O or S;

[0097] The isocyanide compound is more preferably 1,6 - hexane diisocyanide, 2,6 - dimethylphenyl isocyanide or 1,6 - benzene diisocyanide;

[0098] The molar ratio of the amine compound to the isocyanide compound is preferably 1 to 10:2 to 5, more preferably 2 to 9:2 to 4, and even more preferably 4 to 7.5:3 to 4.

[0099] In the present invention, the organic solvent preferably includes at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4 - dioxane, 1,2 - dichloromethane, 1,2 - dichloroethane, N,N - dimethylformamide, N,N - dimethylacetamide and dimethyl sulfoxide, and more preferably N,N - dimethylformamide; when there are two or more of the above - mentioned organic solvents, there is no special limitation on the ratio of different organic solvents.

[0100] In the present invention, the amount of the organic solvent used in the reaction is not particularly limited and can be adjusted according to the actual situation.

[0101] In the present invention, when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, an alkali compound is preferably added during the mixing process of elemental sulfur, the amine compound, the isocyanide compound, and the organic solvent;

[0102] When the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, an alkali compound is preferably added during the mixing process of elemental sulfur, the amine compound, the isocyanide compound, and the organic solvent;

[0103] In the present invention, the alkali compound preferably includes at least one of triethylamine, DBU, TBD, pyridine, cesium carbonate, potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, potassium fluoride, potassium tert-butoxide, and sodium ethoxide, and is further preferably triethylamine; when there are two or more of the above alkali compounds, there is no special limitation on the ratio of different alkali compounds; the usage amount of the alkali compound can be confirmed according to the actual situation.

[0104] In the present invention, the temperature of the first reaction is preferably 25 to 120 °C, further preferably 30 to 100 °C, and still further preferably 50 to 75 °C; the time is preferably 0.5 to 12 h, further preferably 1 to 8 h, and still further preferably 3 to 6 h; the stirring rate is preferably 100 to 900 rpm, further preferably 200 to 800 rpm, and still further preferably 400 to 600 rpm.

[0105] In the present invention, when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a bifunctional α-bromo ketone compound,

[0106] or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound,

[0107] or when the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound; after the first reaction is completed, it is preferable to purify the obtained product;

[0108] In the present invention, the purification is preferably to dilute with the reaction solvent, then add it to a precipitant, and sequentially carry out standing, filtration, and drying to obtain the thiourea compound; when the thiourea compound is mixed with the α-bromo ketone compound, a part of the organic solvent is preferably added; the type of the organic solvent used is preferably the same as that in the first reaction;

[0109] In the present invention, the reaction solvent is preferably at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and water; more preferably a mixed solvent of methanol and water; when there are two or more of the above reaction solvents, there is no special limitation on the ratio of different reaction solvents; the amount of the reaction solvent used in the purification is not specially limited and can be adjusted according to the actual situation;

[0110] In the present invention, the way of adding the precipitant is preferably dropwise addition; the precipitant is preferably at least one of water, methanol, n-hexane and ethanol, more preferably methanol or water; when there are two or more of the above precipitants, there is no special limitation on the ratio of different precipitants;

[0111] The drying temperature is preferably 20-80 °C, more preferably 30-60 °C, and even more preferably 40-50 °C.

[0112] In the present invention, the monofunctional α-bromo ketone compounds preferably include any one of the following structures:

[0113]

[0114] Wherein, R 6 or R 7 is independently preferably H, F, Cl, Br, I, trifluoromethyl, phenyl, an alkyl group with a carbon chain length of 1-200 or an alkoxy group with a carbon chain length of 1-200, more preferably 1-20;

[0115] m is preferably an integer between 0 and 2000, more preferably 1-200;

[0116] The bifunctional α-bromo ketone compounds preferably include any one of the following structures:

[0117]

[0118] Wherein, m is preferably an integer between 0 and 2000, more preferably 1-500;

[0119] The α-bromo ketone compounds are further preferably 1,6-hexanedi(4-phenyl) bromo ketone, 2-bromoacetophenone, 4,4'-bis(2-bromoacetyl) biphenyl or m-dibromoacetophenone.

[0120] In the present invention, the temperature of the second reaction is preferably 25 to 120 °C, more preferably 50 to 110 °C, and even more preferably 80 to 100 °C; the time is preferably 0.5 to 12 h, more preferably 1 to 8 h, and even more preferably 3 to 6 h; the stirring rate is preferably 100 to 900 rpm, more preferably 200 to 800 rpm, and even more preferably 400 to 600 rpm.

[0121] In the present invention, after the second reaction is completed, it preferably includes mixing the second reaction product with a solvent, and then adding it to a precipitant, and sequentially standing, filtering and drying to obtain the polyiminothiazoline compound;

[0122] The solvent mixed with the second reaction product is preferably at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide; more preferably N,N-dimethylformamide; when there are two or more of the above solvents, there is no special limitation on the ratio of different solvents; the amount of the solvent used in the reaction is not specially limited and can be adjusted according to the actual situation;

[0123] The manner of adding the precipitant is preferably dropwise addition; the precipitant is preferably at least one of water, methanol, n-hexane and ethanol, and more preferably a mixed solvent of methanol and water; when there are two or more of the above precipitants, there is no special limitation on the ratio of different precipitants;

[0124] The drying temperature is preferably 20 to 80 °C, more preferably 40 to 60 °C.

[0125] The present invention provides the polyiminothiazoline compound prepared by the above synthesis method, preferably

[0126]

[0127] The present invention also provides the application of the polyiminothiazoline compound in the field of high refractive index materials, preferably as an antireflection coating for optical devices and as a potential material for microlenses of complementary metal oxide semiconductor image sensors.

[0128] The technical solutions provided by the present invention are described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

[0129] Example 1

[0130] Using elemental sulfur (M1), monofunctional aromatic amine (M3), and bifunctional aliphatic isocyanide compound (M2) as raw materials, a dithiourea compound is obtained under alkali catalysis. Subsequently, it reacts with a bifunctional α-bromo ketone compound (M4) to obtain a polyiminothiazoline compound (P1) with a thiazole ring in the main chain and an imino group in the side chain;

[0131] Among them, monomer M1 is elemental sulfur, purchased from Alfa Aesar;

[0132] M2 is 1,6-hexanediisocyanide, and its synthesis method is as described in the literature (Preparation of Multi-Functional Polyamide Vitrimers via the Ugi Four-Component Polymerization and Oxime-Promoted Transcarbamoylation Reaction. Polym. Chem. 2021, 12, 2009-2015);

[0133] M3 is aniline, purchased from Energy Chemical;

[0134] M4 is 1,6-hexanedi(4-phenyl)bromo ketone, and its synthesis method is as described in the literature (Ultrasound and Water-Mediated Synthesis of Bis-Thiazoles Catalyzed by Fe(SD)3 as Lewis Acid Surfactant-Combined Catalyst. J. Sulfur Chem. 2018, 39, 140-150.);

[0135] The alkali compound is Et3N;

[0136] Using elemental sulfur (M1), monofunctional aromatic amine (M3), and bifunctional aliphatic isocyanide compound (M2) as raw materials, the specific process for obtaining the dithiourea compound (I1) under alkali catalysis is as follows: In a 10 mL polymerization tube, 40.0 mg (1.25 mmol) of elemental sulfur, 68.1 mg (0.5 mmol) of 1,6-hexanediisocyanide, and 1116.3 mg (1.25 mmol) of aniline are added in sequence. 1 mL of N,N-dimethylformamide (DMF) is injected with a syringe, and then 28 μL of Et3N is added. Under a nitrogen atmosphere, the reaction is carried out at 100 °C and stirred at a rate of 400 rpm for 3 h. After the reaction is completed, the reaction mother liquor is obtained. The reaction mother liquor is dissolved in 2 mL of DMF, then dropped into water, allowed to stand, filtered, and dried at 20 °C to obtain the dithiourea compound I1.

[0137] Its reaction equation is as shown in Equation (1):

[0138]

[0139] The dithiourea compound (I1) reacts with the bifunctional α-bromo ketone compound (M4) to obtain a polyiminothiazoline compound (P1) with a thiazole ring in the main chain and an imino group in the side chain, specifically:

[0140] 77.2 mg (0.2 mmol) of the dithiourea compound I1 and 102.4 mg (0.2 mmol) of 1,6-hexanedi(4-phenyl) bromo ketone were successively added to a 10 mL polymerization tube, and 1 mL of N,N-dimethylformamide (DMF) was injected with a syringe. The reaction was carried out at 110 °C and stirred at a rate of 400 rpm for 3 h for the polymerization reaction. After the reaction, the polymerization mother liquor was obtained. The polymerization mother liquor was dissolved in 2 mL of DMF, and then it was dropped into a mixed solvent of methanol and water, allowed to stand, filtered, and dried at 60 °C to obtain the polyiminothiazoline compound P1.

[0141] Its reaction equation is as shown in Equation (2):

[0142]

[0143] The structural formula of the polyiminothiazoline compound P1 is:

[0144]

[0145] After determination and analysis, the yield of the polyiminothiazoline compound P1 is 94%, the weight-average molecular weight is 30900 g / mol, the molecular weight distribution is 2.47, and n is 43.

[0146] Example 2

[0147] Using elemental sulfur (M1), bifunctional aliphatic amine (M6) and monofunctional aromatic isocyanide (M5) as raw materials, the first reaction is carried out at room temperature, and then the bifunctional α-bromo ketone compound (M4) is added for polymerization to obtain a polyiminothiazoline compound (P2) with a thiazole ring in the main chain and an imino group in the side chain;

[0148] Among them, the monomer M1 is elemental sulfur, purchased from Alfa Aesar;

[0149] M4 is 1,6-hexanedi(4-phenyl) bromo ketone, and its synthesis method is the same as that in Example 1;

[0150] M5 is 2,6-dimethylphenyl isocyanide, purchased from Energy Chemical;

[0151] M6 is 1,6-hexanediamine, purchased from Energy Chemical.

[0152] The specific synthesis steps of the polyiminothiazoline compound (P2) are as follows:

[0153] In a 10 mL polymerization tube, 16.0 mg (0.5 mmol) of elemental sulfur, 52.5 mg (0.4 mmol) of 2,6-dimethylphenyl isocyanide, and 23.2 mg (0.2 mmol) of 1,6-hexanediamine were successively added. 1 mL of N,N-dimethylformamide (DMF) was injected with a syringe, and the reaction was carried out at room temperature and stirred at a rate of 400 rpm for 3 h. After the reaction ended, a reaction solution was obtained. 102.4 mg (0.2 mmol) of 1,6-hexanedi(4-phenyl) bromoketone was added to the above reaction solution, and a polymerization reaction was carried out at 110 °C and stirred at a rate of 400 rpm for 3 h. After the polymerization ended, a polymerization mother liquor was obtained. The polymerization mother liquor was dissolved in 2 mL of DMF, and then it was dropped into a mixed solvent of methanol and water, allowed to stand, filtered, and dried at 60 °C to obtain the polyiminothiazoline compound P2.

[0154] Its reaction equation is as shown in Equation (III):

[0155]

[0156] The structural formula of the polyiminothiazoline compound P2 is:

[0157]

[0158] After determination and analysis, the yield of the polyiminothiazoline compound P2 was 99%, the weight-average molecular weight was 37900 g / mol, and the molecular weight distribution was 3.28.

[0159] Example 3

[0160] Using elemental sulfur (M1), bifunctional aliphatic amine (M6), and bifunctional aromatic isocyanide compound (M7), the raw materials were subjected to a first reaction at room temperature to obtain a polythiourea compound (PTU). Subsequently, the polythiourea compound (PTU) was polymerized with a monofunctional α-bromoketone compound (M8) to obtain a polyiminothiazoline compound (P3) with thiazole rings and imino groups on the main chain;

[0161] Among them, monomer M1 is elemental sulfur, purchased from Alfa Aesar;

[0162] M7 is 1,6-benzenediisocyanide, and its synthesis method is as described in the literature (Room-Temperature Metal-Free Multicomponent Polymerizations of Elemental Selenium toward Stable Alicyclic Poly(oxaselenolane)s with High Refractive Index. J. Am. Chem. Soc. 2021, 143, 15723-15731.);

[0163] M6 is 1,6-hexanediamine, purchased from Energy Chemical;

[0164] M8 is 2-bromoacetophenone, purchased from Energy Chemical;

[0165] Elemental sulfur (M1), bifunctional aliphatic amine (M6), and bifunctional aromatic isocyanide compound (M7). The raw materials undergo a first reaction at room temperature to obtain a polythiourea compound (PTU). Specifically: In a 10-milliliter polymerization tube, 40.0 mg (1.25 mmol) of elemental sulfur, 64.0 mg (0.50 mmol) of 1,6-benzenediisocyanide, and 58.1 mg (0.50 mmol) of 1,6-hexanediamine are added in sequence. 1 mL of N,N-dimethylformamide (DMF) is injected with a syringe, and the reaction is carried out at room temperature with stirring at a rate of 400 rpm for 3 h. After the reaction is completed, the reaction mother liquor is obtained. The reaction mother liquor is dissolved in 2 mL of DMF, and then it is dropped into methanol, allowed to stand, filtered, and dried at 50 °C to obtain the polythiourea compound PTU;

[0166] Its reaction equation is as shown in Equation (IV):

[0167]

[0168] The polythiourea compound (PTU) is polymerized with a monofunctional α-bromo ketone compound (M8) to obtain a polyiminothiazoline compound (P3) with thiazole rings and imino groups on the main chain. Specifically:

[0169] In a 10-milliliter polymerization tube, 129.3 mg (0.4 mmol) of the polythiourea compound PTU and 159.2 mg (0.8 mmol) of 2-bromoacetophenone are added in sequence. 1 mL of N,N-dimethylformamide (DMF) is injected with a syringe, and the polymerization reaction is carried out at 110 °C with stirring at a rate of 400 rpm for 3 h. After the polymerization reaction is completed, the polymerization mother liquor is obtained. The polymerization mother liquor is dissolved in 2 mL of DMF, and then it is dropped into a mixed solvent of methanol and water, allowed to stand, filtered, and dried at 60 °C to obtain the polyiminothiazoline compound P3;

[0170] Its reaction equation is as shown in Equation (V):

[0171]

[0172] The structural formula of the polyiminothiazoline compound P3 is as follows:

[0173]

[0174] The reaction equation diagrams for preparing the polyiminothiazoline compounds P1, P2, and P3 in Examples 1 to 3 are as Figure 1 shown.

[0175] Example 4

[0176] The dithiourea compound I1 prepared by the method described in Example 1 was reacted with the monofunctional α-bromo ketone compound (M10) to obtain the polyiminothiazoline compound (P4) with a thiazole ring in the main chain and an imino group in the side chain;

[0177] M10 is 4,4'-bis(2-bromoacetyl)biphenyl, purchased from Energy Chemical (Anhui Zesheng Technology Co., Ltd.);

[0178] 77.2 mg (0.2 mmol) of the dithiourea compound I1 and 79.2 mg (0.2 mmol) of 4,4'-bis(2-bromoacetyl)biphenyl were successively added to a 10 mL polymerization tube, and 1 mL of N,N-dimethylformamide (DMF) was injected with a syringe. The reaction was carried out at 110 °C and stirred at a rate of 400 rpm for 3 h for the polymerization reaction. After the reaction was completed, the polymerization mother liquor was obtained. The polymerization mother liquor was dissolved in 2 mL of DMF, and then it was dropped into a mixed solvent of methanol and water, allowed to stand, filtered, and dried at 60 °C to obtain the polyiminothiazoline compound P4.

[0179] Its reaction equation is as shown in Equation (VI):

[0180]

[0181] The structural formula of the polyiminothiazoline compound P4 is as follows:

[0182]

[0183] After determination and analysis, the yield of the polyiminothiazoline compound P4 was 93%, the weight-average molecular weight was 20600 g / mol, the molecular weight distribution was 2.12, and n was 34.

[0184] Example 5

[0185] The dithiourea compound I1 prepared by the method described in Example 1 was reacted with a monofunctional α-bromo ketone compound (M11) to obtain a polyiminothiazoline compound (P5) with a thiazole ring in the main chain and an imino group in the side chain;

[0186] M11 is m-dibromoacetophenone, which was synthesized according to the literature method (Anion Receptors Containing Thiazine-1,1-Dioxide Heterocycles as Hydrogen Bond Donors Beilstein.J.Org.Chem.2010,6,50.);

[0187] 77.2 mg (0.2 mmol) of the dithiourea compound I1 and 63.6 mg (0.2 mmol) of m-dibromoacetophenone were successively added to a 10 mL polymerization tube. 1 mL of N,N-dimethylformamide (DMF) was injected with a syringe, and the reaction was carried out at 110 °C with stirring at a rate of 400 rpm for 3 h for the polymerization reaction. After the reaction was completed, a polymerization mother liquor was obtained. The polymerization mother liquor was dissolved in 2 mL of DMF, and then it was dropped into a mixed solvent of methanol and water, allowed to stand, filtered, and dried at 60 °C to obtain the polyiminothiazoline compound P5.

[0188] The reaction equation is as shown in Equation (VII):

[0189]

[0190] The structural formula of the polyiminothiazoline compound P5 is:

[0191]

[0192] After determination and analysis, the yield of the polyiminothiazoline compound P5 was 93%, the weight-average molecular weight was 11200 g / mol, and the molecular weight distribution was 1.55. (The n value of P5 is 21)

[0193] Synthesize the model compound corresponding to the product described in Synthesis Example 1

[0194] 77.2 mg (0.2 mmol) of the dithiourea compound I1 and 39.6 mg (0.2 mmol) of 2-bromoacetophenone were successively added to a 10 mL polymerization tube. 1 mL of N,N-dimethylformamide (DMF) was injected with a syringe, and the reaction was carried out at 110 °C with stirring at a rate of 400 rpm for 3 h for the reaction. After the reaction was completed, a mother liquor was obtained. The mother liquor was dissolved in 2 mL of DMF, and then it was dropped into a mixed solvent of methanol and water, allowed to stand, filtered, and dried at 60 °C to obtain the iminothiazole model compound M9 corresponding to the product prepared in Example 1;

[0195] Its reaction equation is as shown in Equation (VIII):

[0196]

[0197] The proton nuclear magnetic resonance (¹H NMR) and carbon nuclear magnetic resonance (¹³C NMR) spectra of the polyiminothiazoline compound P1, dithiourea compound I1, and model compound M9 prepared in Example 1 were measured, and the results are as Figure 2 shown (* represents the solvent peak);

[0198] Among them, Figure 2 A is the ¹H NMR spectrum of the dithiourea compound I1, Figure 2 B is the ¹H NMR spectrum of the model compound M9, Figure 2 C is the ¹H NMR spectrum of the polyiminothiazoline compound P1, Figure 2 D is the ¹³C NMR spectrum of the dithiourea compound I1, Figure 2 E is the ¹³C NMR spectrum of the model compound M9, Figure 2 F is the ¹³C NMR spectrum of the polyiminothiazoline compound P1;

[0199] Figure 2 The characteristic peak corresponding to the hydrogen atom on the double bond of the thiazole ring of the polyiminothiazoline compound P1 is at a chemical shift of 6.30 ppm, and the characteristic peak of C=N outside the thiazole ring of the polyiminothiazoline compound P1 is at a chemical shift of 159.42 ppm. Therefore, the structure of the expected polyiminothiazoline compound can be determined.

[0200] The infrared absorption spectra of the raw material M4(A), dithiourea compound I1(B), model compound M9(C), and the prepared polyiminothiazoline compound P1 in Example 1 were measured, and the results are as Figure 3 shown;

[0201] It can be seen from Figure 3 that after the reaction of the raw materials M4 / M8 and the dithiourea compound I1, new stretching vibration peaks of C=N (1561 cm -1 and 1567 cm -1 ) appear in the infrared spectra of the model compound M9 and the synthesized polyiminothiazoline compound P1. At the same time, there are no stretching vibration peaks of C=O (1679 cm -1 ) belonging to α-bromoketone compounds and stretching vibration peaks of N-H (3232 cm -1 ) and C=S (1542 cm -1 ) belonging to the dithiourea compound I1. This indicates that after the second-step reaction, the α-bromoketone compound and the dithiourea compound are successfully converted into the polyiminothiazoline compound.

[0202] The nuclear magnetic resonance hydrogen spectra of the polyiminothiazoline compounds prepared in Example 2 (A), Example 3 (B), Example 4 (C) and Example 5 (D) were detected, and the results are as Figure 4 shown;

[0203] The nuclear magnetic resonance carbon spectra of the polyiminothiazoline compounds prepared in Example 2 (A), Example 4 (B) and Example 5 (C) were detected, and the results are as Figure 5 shown;

[0204] By Figure 4 , the Hc with a chemical shift at 6.09 - 6.57 ppm corresponds to the characteristic peak of the hydrogen atom on the double bond of the thiazole ring of the polyiminothiazoline compounds P2 - P5. By Figure 5 , the C2 with a chemical shift at 158.63 - 159.55 ppm corresponds to the characteristic peak of the carbon atom on the C=N double bond outside the thiazole ring of the polyiminothiazoline compounds P2, P4 and P5. Therefore, the structures of the expected polyiminothiazoline compounds P2 - P5 can be determined.

[0205] The thermogravimetric analysis was carried out on the polyiminothiazoline compounds with thiazole rings in the main chain and imino groups in the side chain prepared in Example 1 (P1), Example 2 (P2), Example 4 (P4) and Example 5 (P5). The obtained thermogravimetric curves are as Figure 6 shown;

[0206] It can be seen from Figure 6 that the temperature corresponding to 5% weight loss of this type of sulfur - containing heterocyclic polymer is 340 - 369 °C, indicating that this type of sulfur - containing heterocyclic polymer has good thermal stability.

[0207] The polyiminothiazoline compounds (30 mg) prepared in Example 1, Example 4 and Example 5 were respectively dissolved in a mixed solvent of 0.9 mL of N,N - dimethylacetamide (DMAc) and 0.1 mL of chlorobenzene, then filtered through a 200 - μm nylon filter membrane, and 30 μL of the filtrate was dropped on a 2 cm * 2 cm silicon wafer for spin - coating to obtain a thin film.

[0208] The selected spin - coater model is KW - 41, and the rotation speed is 1000 rpm. After drying the prepared thin film, the refractive index was measured by a variable - angle spectroscopic ellipsometer (Vertical VASE (V - VASE)) at a wavelength of 400 - 1700 nm; among them, when detecting P1 prepared in Example 1, the thickness is 85 nm; when detecting P4 prepared in Example 4, the thickness is 45 nm; when detecting P5 prepared in Example 5, the thickness is 202 nm; the results are as Figure 7 shown;

[0209] It can be seen from Figure 7It can be seen that the refractive index of this type of polymer at 633 nm can reach 1.8056, which is much higher than that of common polymers, and has potential applications in the fields of optics and optoelectronics.

[0210] The polyiminothiazoline compound P3 prepared in Example 3 and its corresponding polythiourea compound PTU were subjected to thermogravimetric detection, and the results are as Figure 8 shown;

[0211] From Figure 8 it can be seen that the temperatures corresponding to a 5% weight loss of the polyiminothiazoline compound P3 and its corresponding polythiourea compound PTU are 299 °C and 234 °C respectively, indicating that this type of sulfur-containing heterocyclic polymer has higher thermal stability.

[0212] As can be seen from the above examples, the present invention provides a method for in-situ constructing a polyiminothiazoline compound with a thiazole ring in the main chain and an imino group in the side chain, and fully utilizes the great advantage of the adjustable multi-component polymerization monomers. By simply swapping the monomers, the goal of in-situ constructing a polyiminothiazoline compound with a thiazole ring in the main chain and an imino group in the side chain from elemental sulfur in one pot is achieved. The present invention also obtains a polyiminothiazoline with both thiazole rings and imino groups in the main chain through post-functionalization of polythiourea. The polymerization process does not involve any toxic metal catalysts, is simple, efficient, economical, and environmentally friendly, and its products have the characteristics of high regioselectivity and adjustable structure. It can be seen through experimental verification that the polyiminothiazolines synthesized by the present invention all have good thermal stability, good film-forming properties, and relatively high refractive indices, and have potential application values in the field of high refractive index materials, and can be used as antireflection coatings for optical devices and microlenses for complementary metal oxide semiconductor image sensors, etc.

[0213] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for synthesizing a polyiminothiazoline compound, characterized in that, It comprises the following steps: Under a protective atmosphere, elemental sulfur, an amine compound, an isocyanide compound, and an organic solvent are mixed to undergo a first reaction to obtain a thiourea compound; The thiourea compound is mixed with an α-bromo ketone compound to undergo a second reaction to obtain a polyiminothiazoline compound; The amine compound includes a monofunctional aromatic amine, a bifunctional aliphatic amine, or a bifunctional aromatic amine; The isocyanide compound includes a bifunctional aliphatic isocyanide compound, a monofunctional aromatic isocyanide compound, or a bifunctional aromatic isocyanide compound; The α-bromo ketone compound includes a monofunctional α-bromo ketone compound or a bifunctional α-bromo ketone compound.

2. The method for synthesizing a polyiminothiazoline compound according to claim 1, wherein when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the molar ratio of the thiourea compound to the α-bromo ketone compound is 1 to 10: 1 to 100; or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound, and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is 1 to 10: 1 to 100; or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aromatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is 1 to 10: 1 to 100; or when the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the molar ratio of the amine compound to the α-bromo ketone compound is 1 to 10: 1 to 100.

3. The synthesis method of the polyiminothiazoline compound according to claim 2, characterized in that, When the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a bifunctional α-bromo ketone compound, the first reaction further includes an alkali compound; or when the amine compound is a bifunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide compound, and the α-bromo ketone compound is a monofunctional α-bromo ketone compound, the first step reaction further includes an alkali compound.

4. The synthesis method of the polyiminothiazoline compound according to any one of claims 1 to 3, characterized in that, The monofunctional aromatic amine includes any one of the following structures: Among them, R 1 , R 2 and R 3 are independently H, F, Cl, Br, I, hydroxyl group, mercapto group, trifluoromethyl group, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200; The bifunctional aliphatic amine includes any one of the following structures: wherein, m is an integer between 0 and 2000; The bifunctional aromatic amine includes any one of the following structures: m is an integer between 0 and 2000; R 4 is a hydrogen atom or an alkyl group with a carbon chain length of 1 to 200; X is CH2, O or S; The molar ratio of the elemental sulfur to the amine compound is 2 to 20: 1 to 5.

5. The method for synthesizing a polyiminothiazoline compound according to any one of claims 1 to 3, It is characterized in that The monofunctional aromatic isocyanide compound includes any one of the following structures: Among them, R 5 is H, F, Cl, Br, I, trifluoromethyl, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200; The bifunctional aliphatic isocyanide compound includes any one of the following structures: wherein, m is an integer between 0 and 2000; The bifunctional aromatic isocyanide compound includes any one of the following structures: wherein, R 4 is a hydrogen atom or an alkyl group having a carbon chain length of 1 to 200; X is CH2, O or S; The molar ratio of the amine compound to the isocyanide compound is 1 to 10: 2 to 5.

6. The synthesis method of the polyiminothiazoline compound according to claim 1, characterized in that, The temperature of the first reaction is 25 to 120 °C, the time is 0.5 to 12 h, and the stirring rate is 100 to 900 rpm.

7. The synthesis method of the polyiminothiazoline compound according to any one of claims 1 to 3, characterized in that, The monofunctional α-bromo ketone compound includes any one of the following structures: wherein, R 6 or R 7 is independently H, F, Cl, Br, I, trifluoromethyl, phenyl, an alkyl group having a carbon chain length of 1 to 2000, or an alkoxy group having a carbon chain length of 1 to 2000; m is an integer between 0 and 2000; The bifunctional α-bromo ketone compound includes any one of the following structures: Wherein, m is an integer between 0 and 2000.

8. The synthesis method of the polyiminothiazoline compound according to claim 1, characterized in that, The temperature of the second polymerization reaction is 25 to 120 °C, the time is 0.5 to 12 h, and the stirring rate is 100 to 900 rpm.

9. The polyiminothiazoline compound prepared by the synthesis method according to any one of claims 1 to 8.

10. The application of the polyiminothiazoline compound according to claim 9 in the field of high refractive index materials.

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