KR0148038B1 - Side chain type non-linear optical polymer with glycidyl methacrylate copolymer - Google Patents

Abstract

The present invention relates to a copolymer material of a vinyl-based nonlinear optical property monomer with glycidyl methacrylate having an addition polymerizability represented by the following formula, and has excellent heat resistance, transparency, and thinning with high secondary nonlinear optical properties. Combines processability.

Wherein the sum of m and n is 5-10000 and the ratio of n to the sum of m and n is 0.05 to 0.95; R is hydrogen, a saturated hydrocarbon having 1 to 6 carbon atoms, a halogen atom or a fluorinated carbon having 1 to 6 carbon atoms X is absent or methylene or an aromatic hydrocarbon having 6 to 12 carbon atoms; Y is a bonding group selected from the group consisting of ethers, esters, amides and sulfones; NLO is a general secondary nonlinear optical property in which electron donors and electron acceptors are substituted It's a chemical group.

Description

Side chain type nonlinear optical property polymer compound having glycidyl methacrylate as copolymer component and optical material prepared therefrom

1 is a schematic diagram of a full-length polarization method of a branched nonlinear optical characteristic polymer compound having the glycidyl methacrylate of the present invention as a copolymer component.

FIG. 2 compares the temperature stability of the nonlinear optical constant r ₃₃ of the side chain nonlinear optical characteristic polymer compound of the present invention with the metal methacrylate side chain nonlinear optical characteristic polymer which is a conventional side chain polymer.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high performance secondary nonlinear optical characteristic polymer compound that can be used for ultrafast electro-optic modulators for large capacity optical communications, wavelength converting devices of semiconductor lasers, and the like, and optical materials prepared therefrom.

Nonlinear optical material is a core material of optoelectronic technology (widely optical technology) that enables ultra-high speed, high density, high capacity information communication, storage, and operation beyond the limitations of the existing semiconductor fine technology, and is used for semiconductor, ferroelectric inorganic crystal, organic compound, etc. Material development has been intensively targeted. As a result of these studies, the molecular organic compounds mainly composed of conjugated π-electrons are superior to nonlinear optical materials, as described in the 1994 issue of the American Chemical Review, vol. 1, pp. 1-278. The fact that it has characteristics has been proved theoretically and experimentally, and research on it is very active.

In particular, the branched secondary nonlinear optical properties organic polymer materials described in US Pat. Nos. 4,694,066, 4,775,574, and 4,762,912 are integrated due to their excellent processability, transparency, and high nonlinear optical constants over LiNbO ₃ , a commercial nonlinear optical crystal. It is evaluated as the most ideal material for the manufacture of optical waveguide type ultrafast electro-optic modulator. As a specific example, these materials are used in the trial fabrication of ultrafast modulation devices in the tens of GHz bands, as described in Journal of Ploymer Science, Vol. 53, pages 649-663 (1994).

Such a secondary nonlinear optical material may be prepared by thinning an organic compound prepared by directly bonding a chemical group having a high molecular superpolarization to a side chain of a polymer by spin coating or the like.

The prepared secondary nonlinear optical material forms an asymmetrical structure in which the dipole moments of the chemical groups are oriented in one direction through electric field polarization at an appropriate temperature. This asymmetric orientation structure has an important relationship to the properties of the secondary nonlinear optical element. In other words, the device characteristics increase primarily in proportion to the dipole orientation of the asymmetric structure. Therefore, it is very important to suppress the polarization of the electric field that can give the maximum degree of orientation and the relaxation of the orientation in the device fabrication or device use conditions. Do. In general, the asymmetric structure can be easily performed by corona discharge or electric field polarization using an electrode, but a special method is needed to suppress spontaneous thermal orientation relaxation to a symmetric structure that is energy stable under device fabrication or use conditions. Do.

There are two methods of suppressing spontaneous thermal alignment relaxation, which are broadly divided into (1) a method of forming a crosslinked structure of a compound by heat or light during polarization treatment, and (2) a method using a side chain type secondary nonlinear optical polymer having a high glass transition temperature. .

A method of utilizing the formation of crosslinked structures of compounds is to use an epoxy-based thermosetting material having a nonlinear optical properties chemical group as disclosed in Applied Physics Letter Vol. 56, pp. 2610-2613. This method highly forms the cross-linked asymmetric alignment structure by appropriately controlling the full-length polarization and thermosetting reactions. In fact, the nonlinear optical constant d ₃₃ is very high at 42 pm / V, and it is also excellent in suppressing passion alignment relaxation by the cross-linking structure. It turned out. However, such a curable crosslinked polymer has a problem that the density distribution is uneven due to the formation of a highly crosslinked structure, and it is difficult to homogeneously manufacture a thin film by using a low molecular weight material. Since it is induced, it is not used for the manufacture of an actual optical element.

On the other hand, the second method, which uses a side chain type secondary nonlinear optical polymer, uses a high molecular weight material so that an optically uniform thin film can be easily produced by spin coating or the like. By polarizing in the vicinity and cooling and immobilizing it, a thin film having high nonlinear optical constant and no light scattering loss can be produced, which is considered to be an ideal material for fabricating integrated optical devices.

However, it is pointed out that such side chain type polymers suffer from thermal relaxation in device fabrication or use environment. As a solution of this, it is proposed to use a nonlinear optical branched polymer having a high glass transition temperature, but even in this case, as the glass transition temperature increases, it becomes difficult to polarize the electric field, and fracture of the nonlinear optical chemical group occurs at a high temperature. Another problem is caused.

Accordingly, the present invention aims to solve the problems of these two methods as a whole, and to develop a new nonlinear optical property polymer material having high nonlinear optical constants, excellent optical properties and thermal stability.

The object of the present invention can be achieved by a branched nonlinear optical polymer compound having glycidyl methacrylate represented by the following formula as a copolymer component.

Wherein the sum of m and n is 5 to 10000 and the ratio of n to the sum of m and n is 0.05 to 0.95; R is hydrogen, an unsaturated hydrocarbon having 1 to 6 carbon atoms, a halogen atom or a fluorinated having 1 to 6 carbon atoms Carbon; X is absent or methylene or aromatic hydrocarbon having 6 to 12 carbon atoms; Y is a bonding group selected from the group consisting of ethers, esters, amides and sulfones; NLO is from a group consisting of secondary or tertiary amines The electron acceptor selected from the group consisting of the selected electron donor and cyano, nitrile or alkylsulfone represents benzene, azobenzene, stilbene or diphenyl substituted at the 1, 4- or 4, 4'-position of the carbon atom.

The polymer compound of the present invention may be prepared by copolymerizing a glycidyl methacrylate (GMA) and a polymerizable monomer (MNLO) in which a nonlinear optical characteristic chemical group is combined by a general polymerization process. Such polymerization can be easily prepared by a conventional polymerization method by dissolving the two monomers in a co-solvent at a predetermined ratio and then adding an initiator.

Glycidyl methacrylate used in the present invention is not different from conventional acrylic esters such as methyl methacrylate described in US Pat. No. 4,808,332 and the like in terms of polymerizability, and shows similar properties in terms of solubility and film-forming ability of the resulting copolymer. However, the glycidyl methacrylate copolymers of the present invention, unlike the conventional acrylic ester copolymers which do not form crosslinks between compounds, are epoxy groups of glycidyl methacrylate upon full-length polarization at 120 ° C. or higher. It causes a crosslinking reaction slowly by its own chemical reaction of the liver.

The present inventors have found that such a crosslinking reaction between the epoxy groups of the glycidyl methacrylate group can effectively prevent the relaxation of the orientation of the sample to prevent thermal deterioration of the nonlinear optical properties. The glycidyl methacrylate copolymer of the present invention is insoluble in a solvent due to the formation of a crosslinked structure after the full-length polarization treatment, and does not reduce the secondary nonlinear optical constant at all even at a temperature of 100 ° C. or higher.

Therefore, it can be seen that the glycidyl methacrylate copolymer of the present invention can simultaneously solve the problems of the curable crosslinked polymer and the side chain type polymer, that is, a material having excellent properties with processability and thermal stability.

Another important feature of the glycidyl methacrylate copolymer material of the present invention is that the reaction to form a crosslink, i.e., the bond formation reactivity between the glycidyl groups involved in the crosslinking is not high, so that the temperature is below the polarization temperature. Does not form cross-linking itself and forms cross-linking only at the temperature of over 120 ℃, which is the full-length polarization temperature, and (2) glycidyl group is directly bonded to the polymer chain. Is not.

In particular, the characteristics in (1) are directly related to the high nonlinear optical constant and the excellent thermal stability. In other words, when a highly chemically reactive epoxy group and an amine or an epoxy group and a carboxylic acid are used for crosslink formation of the nonlinear optical polymer, the crosslinking proceeds at a polarization treatment temperature or lower to inhibit dipole rotation. Therefore, there is a side effect that the efficiency of the polarization treatment is reduced. However, in the copolymer of the present invention, the reactivity for the formation of self-crosslinking between glycidyl methacrylates is low, and at 120 ° C., the full-length polarization temperature near the glass transition temperature, asymmetry due to full-length polarization, as in the conventional branched nonlinear optical polymer The structure is efficiently formed, and then crosslinking occurs while maintaining the asymmetrical structure formed after a certain time at a temperature of 120 ° C. or more, which is a crosslinking temperature, while maintaining the electric field. That is, the glycidyl methacrylate copolymer of the present invention can achieve high nonlinear optical constants and excellent thermal stability at the same time by controlling the orientation polarization treatment and crosslinking formation of the dipoles sequentially.

The high molecular compound of this invention has the outstanding heat resistance which hardly falls nonlinear optical characteristic by formation of the crosslinked structure between glycidyl groups at high temperature. This heat resistance is the most essential factor in the practical fabrication of nonlinear optical devices, and it is well shown that this purpose can be achieved by using glycidyl group as a copolymer.

Hereinafter, the synthesis and properties of the branched nonlinear optical property polymer compound according to the present invention having glycidyl methacrylate as a copolymer component will be described in more detail through several examples and comparative examples, but the present invention is limited thereto. It doesn't happen.

Example 1

This example is a synthesis example of the branched nonlinear optical characteristic high molecular compound of the following structure having glycidyl methacrylate and 4-amino-4'-nitroacetylbene-containing nonlinear optical monomer as a copolymer component.

Glycidyl methacrylate and 4 '-[(methacryloylethyl) methylamino] -4-nitrosotylbine in the amounts shown in Table 1 were dissolved in 25 ml of dimethylformamide, and placed in a polymerization tube. Bisisobutyronitrile (AIBN) was dissolved in 1 mol% concentration. After the polymerization tube was completely degassed by repeating the cooling-vacuum-thawing process, the polymerization was allowed to proceed for 72 hours while the tube was sealed and stirred at a temperature of 80 ° C. The polymerization solution was poured into ethyl ether to precipitate the polymer, and then the polymer was recovered by filtration. The recovered copolymer was purified by repeating the process of dissolving in tetrahydrofuran and reprecipitating in ethyl ether and hexane, which was dried for 72 hours in a vacuum oven to obtain a polymer of the above formula. The composition of the obtained copolymer polymer was quantified by Kjeldahl nitrogen analysis and the results are shown in Table 1.

Example 2

This example shows glycidyl methacrylate and {1- [4- (N-ethylenepiperazyl) -4'-nitrostilbene] -N-[(1,1-dimethyl-m-isopropenyl) benzyl ]} It is the synthesis example of the side chain type nonlinear optical characteristic high molecular compound which has the following structure which has carbamate as a copolymer component.

Glycidyl methacrylate and 1- [4- (N-ethylenepiperazyl) -4'-nitroacetylbene] -N-[(1,1-dimethyl-m-isopropenyl) in the amounts shown in Table 2 Benzyl] carbamate was dissolved in 10 ml of dimethylformamide, placed in a polymerization tube, and azobisisobutyronitrile (AIBN), a polymerization initiator, was dissolved at a concentration of 1 mol%. After the polymerization tube was completely degassed by repeating the cooling-forging-thawing process, the polymerization was proceeded for 72 hours while the tube was sealed and stirred at a temperature of 80 ° C. The polymerization solution was poured into ethyl ether to precipitate the polymer, and then the polymer was recovered by filtration. The recovered copolymer was dissolved and dissolved in tetrahydrofuran and reprecipitated in ethyl ether and hexane, and purified. The polymer was dried for 72 hours in a vacuum oven. The composition of the resulting copolymer polymer was quantified by Kjeldahl nitrogen analysis and the results are shown in Table 2.

Comparative Example 1

In order to compare the properties of the nonlinear optical polymer having the glycidyl methacrylate of the present invention as a copolymer component with those of the existing side chain nonlinear optical polymer, methyl methacrylate described in US Pat. No. 4,694,066 is used as a copolymerization component. The branched nonlinear optical characteristic polymer having the following structure was synthesized.

2.763 g (27.3 mmol) of methyl methacrylate and 10.0 g (27.3 mmol) of 4 '-[(methacryloylethyl) methylamino] -4-nitrostilbene were dissolved in 27 ml of chlorobenzene and placed in a 100 ml two-necked flask. 0.449 g (2.73 mmol) of azobisisobutyronitrile was added and then replaced with nitrogen by flowing nitrogen for 30 minutes. The polymerization was carried out with stirring at a temperature of 75 ° C. for 18 hours. The polymerization solution was poured into cold metalol to precipitate the polymer, which was washed several times with methanol and dried in a vacuum oven for 72 hours to obtain polymer (VI) of the above formula.

Example 3

The nonlinear optical properties of the polymer II prepared in Example 1 having glycidyl methacrylate as a copolymer component were compared with the methyl methacrylate polymer VI of Comparative Example 1, which is a conventional side chain polymer.

On the glass coated with transparent conductive indium tin oxide (ITO), the polymer II solution of Example 1 and the polymer VI solution of Comparative Example 1 were spin-coated and dried, and gold was deposited as an upper electrode to measure a sample for measurement. Prepared. The conductive wires were connected to upper and lower electrodes of the prepared sample, and then polarized. In the case of the polymer Ⅱ sample, as shown in FIG. 1, first, the material was effectively polarized under the conditions of 120 ° C and 40V where the crosslinking reaction rate between glycidyl groups was very low, and the electric field was raised to 60V and the temperature was increased to 140 ° C. It was further raised to ° C to selectively form a crosslinking reaction between glycidyl groups, and cooled to room temperature under an electric field, followed by annealing at 120 ° C. The polymer VI sample of Comparative Example 1 was polarized at 110 ° C. and 60 V to be polarized under the same conditions. Since the polymer VI sample does not undergo a crosslinking reaction, heat treatment is not necessary.

For the measurement of the secondary nonlinear optical constants of each sample, a simple reflective electro-optic measurement method described in Applied Physics Letters, Vol. 56, No. 18, pages 1734-1736 (1990) at helium-neon laser wavelengths was used.

FIG. 2 shows the change of electro-optic properties with time at 100 ° C. of Polymer II and Polymer VI of Comparative Example 1. FIG. The polymer II of the present invention and the polymer VI of the comparative example had initial nonlinear optical constants r _{33 of} 65 pm / V and 55 pm / V, respectively, and 4 ′-[(methacryloylethyl) methylamino] -4, which is the same nonlinear optical group. Although nitrostilbene is used, the polymer of the present invention shows a slightly larger nonlinear optical constant than the conventional polymer.

In addition, the conventional side chain type polymer VI exhibits a very rapid decrease in properties at a temperature of 100 ° C., but the polymer of the present invention shows that the nonlinear optical properties have excellent heat resistance maintained at a temperature of 100 ° C.

Claims (5)

Branched nonlinear optical characteristic polymer compounds having glycidyl methacrylate as a copolymer component represented by the following general formula (1); Wherein the sum of m and n is 5-10000 and the ratio of n to the sum of m and n is 0.05 to 0.95; R is hydrogen, a saturated hydrocarbon having 1 to 6 carbon atoms, a halogen atom or a fluorinated carbon having 1 to 6 carbon atoms X is absent or methylene or aromatic hydrocarbon having 6 to 12 carbon atoms; Y is a bonding group selected from the group consisting of ether, amide and sulfone; NLO is an electron donor selected from the group consisting of secondary or tertiary amines; Electron acceptors selected from the group consisting of cyano, nitrile or alkylsulfone represent benzene, azobenzene, cytylbene or diphenyl substituted at the 1, 4- or 4, 4'-position of the carbon atom. A method for producing a side chain nonlinear optical characteristic polymer compound of general formula (I) by copolymerizing glycidyl methacrylate of general formula (II) and a compound of general formula (III). In the above formula, the definitions for m, n, R, X, Y and NLO are as defined in claim 1. The polymer compound according to claim 1, wherein the sum of m and n is 15-1000. The polymer compound according to claim 1, wherein the compound forms a heat resistant crosslinked structure by self-chemical reaction between glycidyl group groups by heat treatment after full length polarization. A nonlinear optical material made of a polymer compound represented by the following general formula; Wherein the sum of m and n is 5-10000, and the ratio of n to the sum of m and n is 0.05 to 0.95; R is hydrogen, saturated hydrocarbon having 1 to 6 carbon atoms, halogen atom or fluorinated having 1 to 6 carbon atoms X is absent or methylene or aromatic hydrocarbon having 6 to 12 carbon atoms; Y is a bonding group selected from the group consisting of ethers, esters, amides and sulfones; NLO is selected from the group consisting of secondary or tertiary amines An electron acceptor selected from the group consisting of an electron donor and a cyano, nitrile or alkylsulfone represents benzene, azobenzene, stilbene or diphenyl substituted at the 1, 4- or 4, 4'-position of the carbon atom.