Contain 1,3,4-oxadiazole structure bismaleimides and preparation method thereof
Technical field
The invention belongs to technical field of polymer materials, be specifically related to contain 1,3,4-oxadiazole structure bismaleimides and preparation method thereof.
Background technology
Bismaleimides is a kind of important Thermocurable polyimide, has the good characteristic of polyimide, for example: good thermostability, electrical insulation capability, excellent chemicals-resistant burn into radiation hardness, moisture-proof heat and mechanical property etc.Bismaleimides is small molecules thereby the workability energy that has the loop-like epoxy resins again simultaneously, and moulding process is flexible.Two keys at its molecule two ends owing to the strong electrophilic effect that is subjected to two carbonyls have strong Electron Affinities can with diamines, nucleophilic group generation nucleophilic additions such as diphenol also can have power supply property unsaturated double-bond generation copolyreaction with allylic cpd etc.Bismaleimides carries out modification owing to but its molecular structure design mode can react with multiple monomer again by force, can prepare the thermosetting material that satisfies the various uses needs, is widely used in fields such as aerospace, mechano-electronic, communications and transportation.
By 2,5-two (4-aminophenyl)-1,3,4-oxadiazole synthetic 2,5-two (4-dimaleoyl imino phenyl)-1,3,4-oxadiazole (seeing structural formula A) have excellent thermotolerance, high carbon residue rate, high limiting oxygen index(LOI) (LOI) and good flame-retardance.But this monomer molecule structure all is made of inflexible virtue heterocycle, has the symmetry and the rigidity of height, makes it when having above-mentioned plurality of advantages considerable shortcoming be arranged also, for example: very high fusing point, its fusing point is near 300 ℃; Very poor solvability is insoluble in most of organic solvents.High-melting-point makes fusion solidify at once, the curing reaction temperature height, and exothermic heat of reaction is concentrated, and causes the melt-processed difficulty.Poorly solublely also make it not process with solution method.Therefore this monomer is difficult to use in glue paste and matrix material.
A.2,5-two (4-dimaleoyl imino phenyl)-1,3,4-oxadiazole structural formula
Document (polymer, 2007,48) has reported that two kinds contain two 1,3, and the monomeric synthetic method of chain-prolonged type bismaleimides of 4-oxadiazole ring has been studied solvability and curing reaction characteristic.Its solvability has obtained tangible improvement can be dissolved in chloroform, methylene dichloride, N, but dinethylformamide equal solvent fusing point still very high (266 ℃, 263 ℃), and processing characteristics is also very poor.And both having contained high heatproof oxidation performance 1,3,4-oxadiazole heterocycle contains bismaleimides of rotatable fat ether connecting key and preparation method thereof again and does not see as yet that up to now disclosed patent or bibliographical information are arranged.
Summary of the invention
One of purpose of the present invention is to provide a kind of favorable solubility, and fusing point is low, and curing exotherm is steady, and the cured article fine heat-resisting performance contain 1,3,4-oxadiazole structure bismaleimides.It is above-mentioned novel 1,3 that two of purpose of the present invention is to provide, the preparation method of 4-oxadiazole structure bismaleimides.
The present invention solves the technical scheme that its technical problem takes: a class contains 1,3, and 4-oxadiazole structure bismaleimides has following structural formula:
Substituent R in the formula
1To R
4Be hydrogen atom, halogen atom, or C
1To C
20Identical or different fat alkane and derivative thereof, or C
6To C
12Identical or different aromatic hydrocarbon and derivative thereof.
What the present invention relates to contains 1,3, and 4-oxadiazole structure bismaleimides synthetic route is as follows:
Substituent R in the formula
1To R
4Be hydrogen atom, halogen atom, or C
1To C
20Identical or different fat alkane and derivative thereof, or C
6To C
12Identical or different aromatic hydrocarbon and derivative thereof.
Its preparation method may further comprise the steps:
(1) contain 1,3,4-oxadiazole structure span comes the synthetic of amido acid
To contain 1,3, the diamine of 4-oxadiazole structure and maleic anhydride are dissolved in respectively in the aprotic polar solvent, and containing 1,3, the drips of solution of the diamine of 4-oxadiazole structure is added in the maleic anhydride solution then, stir 2~10 hours.After reaction finishes, if be then direct filtration of reaction solvent, with fresh reaction solvent washing leaching cake, vacuum drying with a kind of in acetone, tetrahydrofuran (THF), the ethyl acetate; If with N, a kind of in dinethylformamide, N,N-dimethylacetamide, the N-Methyl pyrrolidone is reaction solvent, in reaction system, drip precipitation agent water, static, suction filtration are with low boiling point solvent methyl alcohol, acetone or tetrahydrofuran (THF) flush cake, vacuum drying.
(2) contain 1,3,4-oxadiazole structure bismaleimides synthetic
Come amido acid to be dissolved in span or be suspended in the aprotic polar solvent, add acetate, be heated to 20~90 ℃, drip triethylamine and diacetyl oxide.Reaction finishes the back reaction solution is slowly splashed in the water, with the sedimentation and filtration that generates, vacuum-drying.
Step (1) is described to contain 1,3, and the mole proportioning of 4-oxadiazole structure aromatic diamine and maleic anhydride is 1: 2~1: 2.5, and temperature of reaction is 0~60 ℃, and the reaction times is 2~10 hours.
The described non-protonic solvent of step (1) is acetone, tetrahydrofuran (THF), ethyl acetate, N, a kind of in dinethylformamide, N,N-dimethylacetamide, the N-Methyl pyrrolidone.The solvent of recommending is a kind of in acetone, tetrahydrofuran (THF), the ethyl acetate.
The described dewatering agent of step (2) is a diacetyl oxide, and temperature of reaction is 20~90 ℃, and the reaction times is 2~10 hours.
The described aprotic polar solvent of step (2) is an acetone, N, dinethylformamide, N,N-dimethylacetamide, the mixed solvent of one or more in the N-Methyl pyrrolidone.
The described acetate of step (2) is one or more mixtures of sodium-acetate, magnesium acetate, nickel acetate and Cobaltous diacetate.
The consumption of the described dewatering agent diacetyl oxide of step (2) is 2~4 times that span comes amido acid, and the consumption of described catalyst of triethylamine is 0.1~2.5 times that span comes amido acid, and the consumption of acetate is that every mole of span of 0.1~3g comes amido acid.
The invention has the beneficial effects as follows that designing and synthesizing a class contains 1,3,4-oxadiazole structure bismaleimides, its primary structure are that fragrant heterocycle structure can keep good thermotolerance; Introducing 1,3, the synthetic characteristics according to it in the time of 4-oxadiazole structure are introduced flexible fat ehter bond at an end of ring, and the spinability of ehter bond has improved the flexibility of molecular structure, also destroyed simultaneously the regularity of molecular structure, its solvability increase, fusing point are reduced; And the reactive group at two ends is in different chemical environments, and its reactive behavior difference can make two key consecutive reactions guarantee that curing reaction heat emits gently.
Description of drawings
The present invention is described further below in conjunction with drawings and Examples.
Fig. 1 be 2-of the present invention to dimaleoyl imino phenyl-5-to dimaleoyl imino Phenoxymethyl-1,3,4-oxadiazole (curve A) and presoma span thereof come the infrared spectra of amido acid (curve B).
Fig. 2 be 2-of the present invention to dimaleoyl imino phenyl-5-to dimaleoyl imino Phenoxymethyl-1,3, the nucleus magnetic hydrogen spectrum of 4-oxadiazole.
Embodiment
Below in conjunction with specific embodiment, further explain the present invention.Its purpose is to understand better the present invention, and unrestricted protection scope of the present invention.
Embodiment 1
2-to dimaleoyl imino phenyl-5-to dimaleoyl imino Phenoxymethyl-1,3,4-oxadiazole synthetic:
(1) 0.11mol maleic anhydride and 50ml acetone are added in the reactor stirring and dissolving.0.05mol is contained 1,3, and 4-oxadiazole structure aromatic diamine is dissolved in the 200ml acetone, slowly is added drop-wise in the reactor then.At room temperature stir 6h.After reaction finishes, the crystal that generates is filtered, use 150ml washing with acetone filter cake again, vacuum-drying obtains yellow span and comes amido acid, productive rate 93%.FT-IR (KBr, cm
-1): [seeing Fig. 1 (B)] 3289,1543 (NH), 1708,1633 (C=O).
(2) the 0.04mol span is come amido acid be suspended in the 150ml acetone, add the 0.15g Cobaltous diacetate, be heated to 60 ℃, drip 6ml triethylamine and 12ml diacetyl oxide, question response liquid becomes constant temperature timing 5h behind the homogeneous phase.Reaction finishes the back reaction solution is slowly splashed in the water of stirring, and the crystal that generates is filtered vacuum-drying.Obtain yellow bismaleimides crystal, productive rate 84%.FT-IR (KBr, cm
-1): [seeing Fig. 1 (A)] 3099,691 (=C-H), 1720 (C=O), 1392,1150 (C-N-C).
1H NMR (400MHz, DMSO-d
6): (see figure 2) δ 8.15 (2H, ArH), 7.63 (2H, ArH), 7.30 (2H, ArH), 7.25 (2H ,-C=CH), 7.23 (2H, J=9.1Hz, ArH), 7.17 (2H ,-C=CH) 5.56 (2H ,-CH
2-).
Embodiment 2
2-to dimaleoyl imino phenyl-5-(3-methyl-4-dimaleoyl imino Phenoxymethyl-1,3,4-oxadiazole synthetic:
(1) 0.11mol maleic anhydride and 30ml acetone are added in the reactor stirring and dissolving.0.05mol is contained methyl and 1,3, and 4-oxadiazole structure aromatic diamine is dissolved in the 120ml acetone, slowly is added drop-wise in the reactor then.At room temperature stir 10h.After reaction finishes, the crystal that generates is filtered, use 100ml washing with acetone filter cake again, vacuum-drying obtains yellow span and comes amido acid, productive rate 95%.FT-IR(KBr,cm
-1):3289,1543(-NH),2963,2926(-CH
3)1708,1633(C=O)。
(2) the 0.04mol span is come amido acid be suspended in the 150ml acetone, add the 0.15g Cobaltous diacetate, be heated to 50 ℃, drip the 7ml triethylamine, question response liquid drips the 10ml diacetyl oxide, constant temperature 7h after becoming homogeneous phase.Reaction finishes the back reaction solution is slowly splashed in the water of stirring, and the crystal that generates is filtered vacuum-drying.Obtain yellow bismaleimides crystal, productive rate 87%.FT-IR(KBr,cm
-1):3097,692(=C-H),2961,2929(-CH
3),1718(C=O),1396,1149(C-N-C)。