CN118146539A - Crosslinked cycloolefin copolymer, preparation method and application thereof - Google Patents

Abstract

The invention relates to the field of organic polymers, in particular to a crosslinked cycloolefin copolymer, a preparation method and application thereof. The crosslinked cycloolefin copolymer provided by the invention has high light transmittance and high refractive index, and is good in formability and heat resistance, and hydrogenation reaction is not needed in the preparation process. The invention prepares the crosslinkable cycloolefin copolymer with arbitrarily adjustable high refractive index group insertion rate through simple, efficient and good heteroatom tolerance ring-opening metathesis polymerization (ROMP), and can endow the crosslinkable cycloolefin copolymer with different compositions and structures; and then cross-linking the cross-linked cycloolefin copolymer and the polythiol by combining with a mercapto-alkene click chemistry reaction, thereby realizing the preparation of the cross-linked cycloolefin copolymer with high light transmittance and high refractive index. Compared with the prior art, the crosslinked cycloolefin copolymer provided by the invention not only has excellent transparency and high refractive index, but also has better thermal stability and higher storage modulus at high temperature.

Description

A cross-linked cycloolefin copolymer and its preparation method and application

Technical Field

The invention relates to the field of organic polymers, in particular to a cross-linked cycloolefin copolymer and a preparation method and application thereof.

Background technique

Cyclic olefin copolymer is an important resin material, mainly used in packaging, biomedicine, optical equipment and semiconductors. Its main advantages are high transparency, high thermal stability, low optical dispersion, low birefringence and low dielectric constant. Currently commercialized cycloolefin resins include cycloolefin copolymers (COC) and cycloolefin polymers (COP). They have excellent comprehensive performance, but their refractive index is relatively low, only about 1.52 to 1.54, which can no longer meet the current application of various scenarios. Therefore, it is meaningful to increase the refractive index of cycloolefin resin while maintaining its original excellent performance, but it is also challenging.

According to the Lorentz-Lorenz equation, the method of increasing the refractive index of a polymer mainly includes introducing substituents with high molar refractive index, low molar volume and high polarity. Therefore, a large number of high molar refractive index groups including aromatic rings, heavy halogen atoms (chlorine, bromine, iodine), sulfur atoms and other metal atoms are introduced into polymers to enhance their refractive index. Among these groups, aromatic rings and sulfur atoms have been widely used to increase the refractive index of polymers. Currently, many studies focus on copolymerizing monomers with aromatic ring substituents to obtain high refractive index polymers. Among them, the molar refractive index of the carbazole group is 56.37cm ³ /mol, which is significantly higher than other groups and is a typical high refractive group. Introducing the carbazole group into the polymer to increase the refractive index is a general strategy. In addition, Chinese patent CN114269809A discloses a method for preparing an aromatic polymer with a sulfoxide structure (>S＝O) in the main chain, and the resulting polymer has high transmittance in the visible light range, and has high refractive index and low dispersion.

Finding a suitable catalyst to introduce high-refractive groups to increase the refractive index is a research hotspot in this field, but the effects of currently known catalysts are not ideal. For example, metallocene catalysts are classic catalysts in the method of introducing high-refractive groups by coordination polymerization. Chinese patent CN115028763B discloses a method for preparing a cycloolefin copolymer containing a high-refractive group. The cycloolefin polymer having a carbazole group in the side chain is obtained by catalyzing ethylene, cycloolefin and α-olefin substituted with a carbazole group through coordination insertion copolymerization with a classic metallocene catalyst. However, the metallocene catalyst has poor tolerance to heteroatoms and low polymerization activity. The insertion rate of the carbazole group is as high as 6.51 mol%, so the maximum refractive index of the obtained cycloolefin polymer is only 1.5998.

Increasing the insertion rate of high refractive index groups by using other polymerization methods is rarely considered because different polymerization methods have certain technical difficulties. For example, the ring-opening metathesis polymerization method not only has expensive catalysts and monomers, but also if the polymerization conditions are slightly unsuitable, the polymer will precipitate or gel, becoming an insoluble and infusible thermosetting resin that cannot be processed.

In addition, COP is prepared by ring-opening metathesis polymerization (ROMP) of cycloolefin monomers and hydrogenation of the main chain double bonds. The harsh reaction conditions of the hydrogenation step limit its large-scale application.

Summary of the invention

In view of this, the technical problem to be solved by the present invention is to provide a cross-linked cycloolefin copolymer and a preparation method and application thereof. The cross-linked cycloolefin copolymer provided by the present invention has high light transmittance and high refractive index, and good formability and heat resistance, and no hydrogenation reaction is required in the preparation process.

The present invention provides a cross-linked cycloolefin copolymer, which is obtained by cross-linking a cross-linkable cycloolefin copolymer and a polythiol;

The cross-linkable cycloolefin copolymer of the present invention has a structure of formula IV;

In formula IV, m and n are independently the degree of polymerization, (m:n)≥0.001; preferably, 0.01≤(m:n)≤20; more preferably, 0.1≤(m:n)≤10.

In the present invention, p and q are independently 0 or 1.

In the present invention, _R1 and _R2 are independently selected from hydrogen, halogen, _C6 - _C14 aryl, C1-C20 saturated alkoxy, _C1 - _C20 unsaturated alkoxy, _{cyano, C1-C20 ester, aldehyde, hydroxyl, carboxyl, C1 - C20 saturated alkyl or} C1- _C20 unsaturated alkyl. Preferably, _R1 and _R2 are independently selected from hydrogen, halogen, phenyl, naphthyl, anthracenyl, biphenyl, _C1 - _C20 saturated alkoxy, _C1 - _C20 unsaturated alkoxy, cyano, _C1 - _{C20 ester} , aldehyde, hydroxyl, carboxyl, _C1 - _C20 saturated alkyl or _C1 - _C20 unsaturated alkyl; _R1 and _R2 are the same or different. In the present invention, _R1 and _R2 and the carbon atoms to which they are connected can also form a five-membered ring, a six-membered ring or an eight-membered ring. Preferably, _R1 and _R2 and the carbon atoms to which they are connected form a _C5 - _C8 alkene, a _C5 - _C8 cycloalkane or a _C6 - _C12 aromatic ring.

_R3 and _R4 in the present invention are independently selected from hydrogen, _C1 - _C5 alkyl substituted by carbazolyl, _C1 -C3 alkyl substituted by C6- _{C12 arylamino , C1} - _C3 alkyl substituted by C4- _{C13 aryl} , _C1 - _C3 alkyl substituted by _C6 - _C12 arylether, _C1 - _C3 alkyl substituted by C6- _C12 arylthioether, or _C1 - _C3 alkyl substituted by C12- _C32 thiaaryl. Preferably, _R3 and _R4 are independently selected _from hydrogen, _C1 - _C5 alkyl substituted by carbazolyl _, diphenylamino, indolyl, pyrrolyl, biphenylether, biphenylthioether, or _C12 - _C32 thiaaryl. _R3 and _R4 in the present invention are the same or different. In the present invention, R ₃ and R ₄ and the carbon atoms to which they are connected can also form a cyclopentene ring, a thioaryl heterocyclic ring, a spirofluorene ring or a phenanthrocyclobutane ring.

In some technical solutions of the present invention, the cross-linkable cycloolefin copolymer is one of the compounds having the structures of formulas P1 to P9:

The polythiol of the present invention has a structure of formula V;

In Formula V, k is the number of thiol groups, which is an integer greater than 2; preferably, k is an integer of 2-4.

The ^A1 described in the present invention is selected from a _C2 - _C20 alkyl group having only carbon-hydrogen bonds in its skeleton, a _C2 - _C20 alkyl group having an ether bond in its skeleton, a _C2 - _C20 alkyl group having a thioether bond in its skeleton, a _C2 - _C20 alkyl group having an ester group in its skeleton, a _C6 - _C18 aryl group having only carbon-hydrogen bonds in its skeleton, a _C6 - _C18 aryl group having a thioether bond in its skeleton, or a _C6 - _C18 heteroaryl group having a thioether bond in its skeleton.

The "alkyl k group" mentioned in the present invention means a group formed when k carbon atoms in an alkyl group each lose one hydrogen atom; for example, "C ₂ -C ₂₀ alkyl k group" means a group formed when k carbon atoms in a C ₂ -C ₂₀ alkyl group each lose one hydrogen atom; for another example, "C ₂ alkane 2 group" means a group formed when 2 carbon atoms in an alkyl group each lose one hydrogen atom, that is, -CH ₂ -CH ₂ -. The skeleton of the alkyl group in the present invention means the carbon skeleton of the straight-chain alkyl group or the branched alkyl group as a whole; specifically, taking " _C2 - _C20 alkyl group having an ether bond in the skeleton" as an example, it means that in a straight-chain or branched alkyl skeleton composed of 2 to 20 carbon atoms, two directly connected carbon atoms form a group, and at least one group of two carbon atoms is connected by an ether bond; taking " _C6 - _C18 aryl group having a thioether bond in the skeleton" as an example, it means that in an aryl skeleton composed of 6 to 18 carbon atoms, two directly connected carbon atoms form a group, and at least one group of two carbon atoms in the same aromatic ring or different aromatic rings has a thioether bond inserted between them.

More preferably, the ^A1 is selected from a cyclic group or a chain group consisting of 1 to 5 identical or different structural units represented by formula Va:

j _a -A ² ---- Formula Va;

In formula Va, j is S or O; a is 0 or 1; ^A2 is a _C2 - _C3 alkyl group, a _C4 - _C6 aryl group or a _C4 - _C6 heteroaryl group;

or,

The ^A1 is selected from the group represented by the structure of formula Vb;

In formula Vb, A ³ is a C ₁ -C ₆ alkyl group having d substitution positions, preferably a C ₅ -C ₆ alkyl group having d substitution positions; d is an integer of 1 to 4, preferably 3 or 4;

or,

The ^A1 is a _C6 - _C18 aryl group or a _C6 - _C18 heteroaryl group, preferably a _C6 - _C12 aryl group or a _C6 - _C12 heteroaryl group.

In some technical solutions of the present invention, the polythiol is one or more compounds having structures of formula S1 to S17:

In some technical solutions of the present invention, the cross-linked cyclic olefin copolymer is or by cross-linking; or or by cross-linking; or or by cross-linking; or or by cross-linking; or or by cross-linking; or Cross-linked to each other.

The present invention also provides a method for preparing a cross-linked cycloolefin copolymer according to any of the above technical solutions, comprising the following steps:

The photoinitiator, the cross-linkable cycloolefin copolymer and the polythiol are subjected to a cross-linking reaction under ultraviolet light for 0.5 to 1 hour to obtain a cross-linked cycloolefin copolymer.

Specifically, the present invention exposes the mixed solution of the photoinitiator, the crosslinkable cycloolefin copolymer and the polythiol to ultraviolet light for a crosslinking reaction of 0.5 to 1 h to obtain a crosslinked cycloolefin copolymer. The crosslinking reaction of the present invention belongs to a thiol-ene click chemistry reaction, and the ultraviolet light is a light with a wavelength of 200 to 400 nm, preferably a light of 300 to 400 nm, and more preferably a light of 365 nm. The photoinitiator of the present invention is selected from one or more of benzoin dimethyl ether (DMPA), diphenyl acetone, 2,4-dihydroxybenzophenone, and isopropylthioxanthone, preferably selected from benzoin dimethyl ether. The solvent of the mixed solution of the present invention is a common solvent, preferably a linear hydrocarbon compound, a cyclic hydrocarbon compound or an aromatic hydrocarbon compound, more preferably a halogenated hydrocarbon compound, and most preferably chloroform. The mass ratio of the crosslinkable cycloolefin copolymer of the present invention and the photoinitiator is (10 to 100): 1; the molar ratio of the double bonds in the crosslinkable cycloolefin copolymer to the thiol in the polythiol is 1: (1 to 10).

The cross-linkable cycloolefin copolymer of the present invention is obtained by polymerization reaction of a compound having a structure of formula II and a compound having a structure of formula III under the action of a catalyst;

Specifically, in an inert solvent, a compound having a structure of formula II and a compound having a structure of formula III are polymerized under the action of a catalyst to obtain the cross-linkable cycloolefin copolymer.

The polymerization reaction of the present invention is a ring-opening metathesis polymerization reaction, and the catalyst is a ruthenium catalyst, preferably a Grubbs catalyst, and most preferably a G2 catalyst. The temperature of the polymerization reaction is 0 to 60°C, preferably 25°C; the time of the polymerization reaction is 1 to 4 hours, preferably 2 hours. The polymerization reaction of the present invention is carried out in an inert solvent, and the inert solvent is preferably selected from linear hydrocarbon compounds, cyclic hydrocarbon compounds or aromatic hydrocarbon compounds, more preferably halogenated hydrocarbon compounds, and most preferably dichloromethane.

After the polymerization reaction of the present invention is completed, the reaction solution obtained by the polymerization reaction is further post-treated, specifically: adding an appropriate amount of molecular weight regulator to the reaction solution obtained after the polymerization reaction and reacting for 0.5 to 1 hour, mixing the reaction solution with a large amount of ethanol after the reaction, and filtering to obtain a cross-linkable cycloolefin copolymer. The molecular weight regulator of the polymerization reaction of the present invention is a straight-chain olefin, preferably an alkenyl ether, and more preferably vinyl ethyl ether. The molar ratio of the vinyl ethyl ether of the present invention to the catalyst used in the above-mentioned polymerization reaction process is (500 to 2000):1, preferably 1000:1.

The molar ratio of the compound having the structure of formula II to the compound having the structure of formula III of the present invention is (0.01-100):1, preferably (0.1-10):1; the ratio of the total molar number of the compound having the structure of formula II and the compound having the structure of formula III to the molar number of the ruthenium-based catalyst is (800-1200):1, preferably 1000:1.

R ₁ , R ₂ , R ₃ and R ₄ in the compound having the structure of formula II and the compound having the structure of formula III of the present invention are the same as R ₁ , R ₂ , R ₃ and R ₄ in the cross-linkable cycloolefin copolymer having the structure of formula IV, and will not be described in detail. In some technical schemes of the present invention, the compound having the structure of formula II is selected from one of the compounds having the structures of formula M1 to formula M28:

The compound having the structure of formula III is selected from one of the compounds having the structures of formula HM1 to formula HM14:

The present invention has no particular restrictions on the sources of the compound having the structure of formula II and the compound having the structure of formula III, which can be commercially available products or homemade products. The present invention has no particular restrictions on the preparation methods of the compound having the structure of formula II and the compound having the structure of formula III. The compound having the structure of formula II or the compound having the structure of formula III of the present invention is preferably prepared according to the reaction route shown in Figure 1, which is a reaction route diagram of the compound having the structure of formula II or the compound having the structure of formula III of the present invention.

Specifically, the method for preparing the compound having a structure of Formula II or a compound having a structure of Formula III of the present invention comprises the following steps: reacting dicyclopentadiene, substituted ethylene and 2,6-di-tert-butyl-p-cresol to obtain a compound having a structure of Formula II or a compound having a structure of Formula III;

The substituted ethylene has a structure of formula VI-a or formula VI-b;

The R ₁ , R ₂ , R ₃ and R ₄ are the same as those described above and will not be described in detail.

The molar ratio of the dicyclopentadiene to the substituted ethylene of the present invention is 1:(2-8), more preferably 1:(2-4).

After obtaining the cross-linkable cycloolefin copolymer, the invention conducts structural identification and performance testing on the cross-linkable cycloolefin copolymer, and the specific process is as follows: the invention conducts nuclear magnetic resonance (NMR) detection on the cross-linkable cycloolefin copolymer, including ¹ H-NMR spectrum, ¹³ C-NMR spectrum and DEPT spectrum, and the results show that the cycloolefin copolymer provided by the invention has a structure of formula IV, and the molar ratio of the compound monomers having the structures of formula II and formula III is between (0.1 and 10):1. The invention adopts differential scanning calorimetry (DSC) to measure the glass transition temperature (T _g ) of the cross-linkable cycloolefin copolymer, and the results show that its T _g is between 91.6° C. and 187.1° C. The invention adopts room temperature gel permeation chromatography (GPC) to measure the molecular weight of the cross-linkable cycloolefin copolymer, and the results show that its number average molecular weight is 85 kg/mol to 299 kg/mol, and the molecular weight distribution index is 1.7 to 2.3, and it has good molecular weight adjustability.

The cross-linked cycloolefin copolymer provided by the present invention is mainly used in the field of optical equipment. Specifically, the cross-linked cycloolefin copolymer provided by the present invention can be processed to obtain an optical resin film. In certain technical schemes of the present invention, the cross-linked cycloolefin copolymer film is prepared on a glass plate and a silicon wafer, and the identification and performance test of the relevant structure are performed. The specific process is as follows: The present invention determines the sulfur content of the cross-linked cycloolefin copolymer, and the result shows that the sulfur content of the cross-linked cycloolefin copolymer provided by the present invention is greater than 20wt%. The present invention determines the light transmittance of the cross-linked cycloolefin copolymer film, and the result shows that the cross-linked cycloolefin copolymer film provided by the present invention has high transparency, and the light transmittance in the visible light region is greater than 95%. The present invention uses an ellipsometer to measure the refractive index of the cross-linked cycloolefin copolymer film spin-coated on a silicon wafer, and the result shows that the cross-linked cycloolefin copolymer film provided by the present invention has a high refractive index, and the refractive index at 589nm is adjustable between 1.61 and 1.68. The present invention uses a thermogravimetric analyzer (TGA) to evaluate the thermal stability of the cross-linked cycloolefin copolymer, and the result shows that the 5% weight loss temperature (T _d(5%) ) of the cross-linked cycloolefin copolymer provided by the present invention is greater than 160°C, showing good thermal stability. The present invention also uses dynamic thermal mechanical analysis (DMA) to evaluate the thermomechanical properties of the cross-linked cycloolefin copolymer film. The results show that the cross-linked cycloolefin copolymer provided by the present invention still has a relatively high storage modulus (>10 ⁵ Pa) at high temperatures.

The present invention provides a cross-linked cycloolefin copolymer and a preparation method and application thereof. The cross-linked cycloolefin copolymer provided by the present invention has high light transmittance and high refractive index, and has good formability and heat resistance, and the preparation process does not require hydrogenation reaction. The present invention prepares a cross-linked cycloolefin copolymer with an arbitrarily adjustable high refractive index group insertion rate through a simple, efficient and heteroatom-tolerant ring-opening metathesis polymerization (ROMP), and can give the cross-linked cycloolefin copolymer different compositions and structures; then the cross-linked cycloolefin copolymer and polythiol are cross-linked with each other by combining a mercapto-ene click chemistry reaction, and a cross-linked cycloolefin polymer with a side chain containing a high refractive index group and a polythiol as a cross-linking point is obtained, thereby achieving high light transmittance and high refractive index. Compared with the prior art, the cross-linked cycloolefin copolymer provided by the present invention not only has excellent transparency and high refractive index, but also shows good thermal stability and still has a high storage modulus at high temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a reaction scheme of the compound having the structure of Formula II or the compound having the structure of Formula III of the present invention;

FIG2 is a ¹ H-NMR spectrum of the cycloolefin monomer HM3 of Example 1 of the present invention;

FIG3 is a ¹ H-NMR spectrum of the cross-linkable cycloolefin copolymer P1 of Example 2 of the present invention;

FIG. 4 is a refractive index-wavelength curve diagram of the cross-linked cyclic olefin copolymer CP2 of Example 14 of the present invention.

Detailed ways

The present invention discloses a cross-linked cycloolefin copolymer and a preparation method and application thereof. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the above. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

In a specific embodiment of the present invention, the first cycloolefin monomer is selected from one or more of the above compounds having the structures of formulae HM1 to HM14;

In a specific embodiment of the present invention, the second cycloolefin monomer is selected from one or more of the compounds having the structures of formulas M1 to M28 described above;

In a specific embodiment of the present invention, the cross-linkable cycloolefin copolymer having the structure of formula P1 to P9 can be prepared according to the different cycloolefin monomers used;

In a specific embodiment of the present invention, the polythiol is selected from one or more of the compounds having the structures of formulas S1 to S17 above;

In the specific embodiment of the present invention, cross-linked cycloolefin copolymers having schematic structures of formulas CP1 to CP6 can be prepared according to the selected cross-linkable cycloolefin copolymers and polythiol:

The present invention will be further described below in conjunction with embodiments:

Example 1

The preparation of cycloolefin monomer HM3 is carried out according to the above reaction route, as follows:

3-N-carbazole propene (25.3 g, 122 mmol), dicyclopentadiene (8.0 g, 61 mmol) and a small amount of 2,6-di-tert-butyl-p-cresol (1.1 g, 5.0 mmol) were added to the autoclave. The reaction was stirred at 175°C for about 42 hours. The heating was turned off and the mixture was cooled to room temperature. The crude product was purified by recrystallization to obtain white needle-shaped crystals HM3 (21.9 g, 66%), as shown in FIG2 , which is the ¹ H-NMR spectrum of the cycloolefin monomer HM3 of Example 1 of the present invention.

Example 2

The crosslinkable cycloolefin copolymer P1 was prepared according to the above route, specifically as follows:

In the glove box, 0.44g (1.6mmol) HM3 and 0.26g (1.6mmol) M1 were added to 100mL polymerization bottle respectively, and 40ml dichloromethane was added to fully dissolve under stirring. 2.7mg (3.2μmol) G2 catalyst was dissolved in 2mL dichloromethane, and then the solution was added to the polymerization bottle by a syringe. After 2h of room temperature reaction, 0.5mL molecular weight regulator vinyl ethyl ether was added to the reaction system, and the reaction was stirred for 0.5h. Finally, the polymerization solution was added to 200mL ethanol for sedimentation, the polymer was filtered, and it was dried to constant weight in a vacuum drying oven to obtain crosslinkable cycloolefin copolymer 0.69g. As shown in Figure 3, Figure 3 is the ^1H -NMR spectrogram of the crosslinkable cycloolefin copolymer P1 of Example 2 of the present invention.

Embodiments 3 to 12

Preparation of cross-linkable cycloolefin copolymers of different compositions and structures:

In the glove box, a certain molar amount of the first cycloolefin monomer and the second cycloolefin monomer are added to the polymerization bottle respectively, and 40mL of dichloromethane is added and stirred to fully dissolve. A certain amount ( ^10-3 of the total molar amount of the cycloolefin monomer) of G2 catalyst is dissolved in 2mL of dichloromethane, and then the solution is added to the polymerization bottle by a syringe. After 2h of room temperature reaction, 0.5mL of molecular weight regulator vinyl ethyl ether is added to the reaction system, and the reaction is stirred for 0.5h. Finally, the polymerization solution is added to 200mL of ethanol for sedimentation, the polymer is filtered, and it is dried to constant weight in a vacuum oven to obtain a crosslinkable cycloolefin copolymer, and the specific reaction conditions and product structural formula are shown in Table 1.

Comparative Example 1

Preparation of Cyclic Olefin Copolymer P9:

Different from the embodiment, the polymerization system used in Comparative Example 1 is as follows: 0.26g (1.6mmol) M1 and 0.21g (1.6mmol) M2 are added to the polymerization reaction bottle in the glove box, and 40mL cyclohexane is added and fully dissolved under stirring. 0.2mL of 1-hexene, 0.1mL of anhydrous ethanol and 0.04mL of triisobutylaluminum solution are added to the solution and fully stirred. 0.028g of tungsten hexachloride is added to a 100mL branched bottle, and 25mL of cyclohexane is added to the branched bottle and stirred for 15 minutes to fully dissolve the tungsten hexachloride in cyclohexane to obtain a solution of tungsten hexachloride. Under stirring, 0.4mL of the tungsten hexachloride solution is added to the above-mentioned polymerization reaction bottle for 2h of polymerization reaction. Finally, the polymerization reaction solution is added to 200mL ethanol for sedimentation, the polymer is filtered, and it is dried to constant weight in a vacuum oven to obtain 0.45g of a cross-linkable cycloolefin copolymer.

The specific reaction conditions, product structural formulas and yields of Examples 2 to 12 and Comparative Example 1 are listed in Table 1. The test results of M _n , M _w /M _n and T _g of the products are also shown in Table 1:

Table 1

Note: All data in Table 1 are based on the results of at least two parallel tests (unless otherwise specified). _Mn is the number average molecular weight, _Mw / _Mn is the polymer dispersibility index, _Mn and _Mw / _Mn are measured by GPC at 40°C in tetrahydrofuran, relative to polystyrene standards; _Tg is measured by DSC.

As shown in Table 1, by adjusting the type and ratio of cycloolefin monomers, crosslinkable cycloolefin copolymers of different compositions and structures can be obtained, the insertion rate of high refractive index groups can be adjusted arbitrarily, the yield can reach 100% and there is no gel. The number average molecular weight of the obtained cycloolefin copolymer is 22kg/mol to 299kg/mol, the molecular weight distribution index is 1.7 to 3.1, it has good molecular weight adjustability, and _Tg is between 91.6℃ and 187.1℃.

Examples 13 to 18

Preparation of cross-linked cycloolefin copolymers by cross-linking of cross-linkable cycloolefin copolymers by mercapto-ene reaction:

At room temperature, a certain amount of cross-linkable cycloolefin copolymer, polythiol and photoinitiator benzoin dimethyl ether (DMPA) are added to 5 mL of chloroform, and the mixed solution after full dissolution is poured on a glass plate or spin-coated on a silicon wafer, and then exposed to a 365 nm ultraviolet lamp for reaction for 0.5 h. After the reaction is completed, the excess solvent is removed in a vacuum oven to obtain a cross-linked cycloolefin copolymer film. The specific reaction conditions and product structural formulas of Examples 13 to 18 are shown in Table 2. The cross-linked cycloolefin copolymer film products of Examples 13 to 18 and the cross-linkable polymers of Example 2 and Comparative Example 1 are tested for transmittance, refractive index and 5 wt% thermal weight loss temperature (T _d (5%)), and the results are listed in Table 2.

Table 2

Note: All data in Table 2 are based on the results of at least two parallel tests (unless otherwise stated).

As shown in Table 2, the light transmittance of the cross-linked cycloolefin copolymer film prepared by cross-linking the cross-linkable cycloolefin copolymer and the polythiol through the thiol-ene reaction is greater than 95%. Compared with the polymer obtained in Example 2 without cross-linking, the refractive index of the polymer film of Example 13 after cross-linking is increased by 0.053, indicating that the introduction of sulfur atoms through the thiol-ene reaction cross-linking not only gives the polymer film better high-temperature dimensional stability and better thermal stability, but also greatly improves the refractive index. Compared with the classic cycloolefin copolymer prepared in Comparative Example 1, the refractive index of the cross-linked cycloolefin copolymer is higher, and the refractive index at 589nm is adjustable between 1.61 and 1.68 by regulating the polymer structure. The 5wt% weight loss temperature (Td _(5%) ) of the cross-linked cycloolefin copolymer is>160℃, showing good thermal stability. Among them, the refractive index of the product of Example 14 is the highest, as shown in Figure 4, which is a refractive index-wavelength curve of the cross-linked cycloolefin copolymer CP2 of Example 14 of the present invention. It can be seen from Figure 4 that the refractive index of the cross-linked cycloolefin copolymer CP2 of Example 14 of the present invention can reach 1.684 at a wavelength of 589nm.

Comparative Example 2

Preparation of Cyclic Olefin Copolymer A

First, a 75 mL glass pressure reactor connected to a gas pipeline was vacuum dried at 90 ° C for at least 1 h. Then, 23 mL of toluene and 0.1 mol/L of comonomers M1 and HM3 were added to the reactor under an inert atmosphere, and then 10.0 μmol of a late transition metal catalyst was dissolved in 2 mL of dichloromethane and injected into the polymerization system through a syringe. Under rapid stirring (750 rpm), ethylene was introduced and maintained at 8 bar. After 2 h, the pressure reactor was evacuated, 200 mL of hydrochloric acid ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried in a vacuum oven to constant weight to obtain 0.4 g of a polymer with a transmittance of 95%, a refractive index (589 nm) of 1.614, and a T _d (5%) of 420 ° C. The ¹ H-NMR spectrum shows that the insertion rate of the cycloolefin monomer HM3 containing carbazole groups is 14.0%. Compared with metallocene catalysts, the tolerance has been greatly improved, but the ring-opening metathesis polymerization can achieve the insertion rate of the cycloolefin monomer HM3 containing carbazole groups. The ratio can be adjusted arbitrarily, and the product obtained after the ring-opening metathesis polymerization can be cross-linked with polythiol to further increase the refractive index.

The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (10)

1. A cross-linked cycloolefin copolymer, characterized in that it is obtained by cross-linking a cross-linkable cycloolefin copolymer and a polythiol; The cross-linkable cycloolefin copolymer has a structure of formula IV; In formula IV, m and n are independently the degree of polymerization, m:n≥0.001; Said p and q are independently 0 or 1; The _R1 and _R2 are independently selected from hydrogen, halogen, _C6 - _C14 aryl, C1- _C20 saturated alkoxy, _C1 - _C20 unsaturated alkoxy, cyano, _C1 -C20 ester, aldehyde, hydroxyl, carboxyl, _C1 - _C20 saturated alkyl or _C1 - _C20 unsaturated alkyl; or, _{the R1} and _R2 and the carbon atoms to _which they are connected form a five-membered ring, a six-membered ring or an eight-membered ring; Said _R3 and _R4 are independently selected from hydrogen, _C1 -C5 alkyl substituted by carbazolyl, _C1 - _C3 alkyl substituted by C6- _C12 arylamino, _C1 - _C3 alkyl substituted by C6-C14 aryl, _C1 - _C3 alkyl substituted by _C6 - _C12 arylether, _C1 - _C3 alkyl substituted by _C6 - _C12 arylthioether or _C1 - _C3 alkyl substituted by _{C12 - C32} thioaryl; or, said _R3 and _R4 and their respective carbon atoms connected _form a cyclopentene ring, a thioaryl heterocyclic ring, a spirofluorene _{ring or} a phenanthrocyclobutane; The polythiol has a structure of formula V; In Formula V, k is an integer greater than 2; The ^A1 is selected from a _C2 - _C20 alkyl group having only carbon-hydrogen bonds in its skeleton, a _C2 - _C20 alkyl group having an ether bond in its skeleton, a _C2 - _C20 alkyl group having a thioether bond in its skeleton, a _C2 - _C20 alkyl group having an ester group in its skeleton, a _C6 - _C18 aryl group having only carbon-hydrogen bonds in its skeleton, a _C6 - _C18 aryl group having a thioether bond in its skeleton, or a _C6 - _C18 heteroaryl group having a thioether bond in its skeleton. 2. The cross-linked cyclic olefin copolymer according to claim 1, characterized in that, in formula IV, _R1 and _R2 are independently selected from hydrogen, halogen, phenyl, naphthyl, anthracenyl, biphenyl, _C1 - _C20 saturated alkoxy, C1- _C20 unsaturated alkoxy, _{cyano, C1-C20 ester, aldehyde, hydroxyl, carboxyl, C1 - C20 saturated alkyl} or _C1 - _C20 unsaturated alkyl; _R3 and _R4 are independently selected from hydrogen, _C1 - _C5 alkyl substituted by carbazolyl, diphenylamino, indolyl, pyrrolyl, biphenyl ether, biphenyl sulfide or _C12 - _C32 thioaryl substituted _C1 - _C3 alkyl; In formula V, k is an integer of 2 to 4; In Formula V, ^A1 is selected from a cyclic group or a chain group consisting of 1 to 5 identical or different structural units represented by Formula Va: j _a —A ^2____ formula Va; In formula Va, j is S or O; a is 0 or 1; ^A2 is a _C2 - _C3 alkyl group, a _C4 - _C6 aryl group or a _C4 - _C6 heteroaryl group; or, The ^A1 is selected from the group represented by the structure of formula Vb; In formula Vb, A ³ is a C ₁ -C ₆ alkyl group having d substitution positions, and d is an integer of 1 to 4; or, The A ¹ is selected from a C ₆ ～C ₁₈ aryl group or a C ₆ ～C ₁₈ heteroaryl group. 3. The cross-linked cycloolefin copolymer according to claim 1, characterized in that the cross-linkable cycloolefin copolymer is one of the compounds having the structures of formulas P1 to P9: The polythiol is one or more compounds having structures of formula S1 to S17: 4. The cross-linked cycloolefin copolymer according to claim 1, characterized in that it is composed of Cross-linked to obtain; or, Depend on Cross-linked to obtain; or, Depend on Cross-linked to obtain; or, Depend on Cross-linked to obtain; or, Depend on Cross-linked to obtain; or, Depend on Cross-linked to each other. 5. The method for preparing the cross-linked cycloolefin copolymer according to any one of claims 1 to 4, characterized in that it comprises the following steps: The photoinitiator, the cross-linkable cycloolefin copolymer and the polythiol are subjected to a cross-linking reaction under ultraviolet light for 0.5 to 1 hour to obtain a cross-linked cycloolefin copolymer. 6. The preparation method according to claim 5, characterized in that the mass ratio of the cross-linkable cycloolefin copolymer to the photoinitiator is (10-100):1; The molar ratio of the double bonds in the cross-linkable cycloolefin copolymer to the mercapto groups in the polythiol is 1:(1-10). 7. The preparation method according to claim 5, characterized in that the cross-linkable cycloolefin copolymer is obtained by polymerization reaction of a compound having a structure of formula II and a compound having a structure of formula III under the action of a catalyst; The catalyst is a ruthenium-based catalyst. 8 . The preparation method according to claim 7 , characterized in that the polymerization reaction temperature is 25° C. and the polymerization reaction time is 2 h. 9. The preparation method according to claim 7, characterized in that the molar ratio of the compound having the structure of formula II to the compound having the structure of formula III is (0.01-100):1; The ratio of the total number of moles of the compound having the structure of formula II and the compound having the structure of formula III to the number of moles of the ruthenium-based catalyst is (800-1200):1. 10. An optical resin film obtained by processing the cross-linked cycloolefin copolymer according to any one of claims 1 to 4.