A kind of method of cyclosiloxane anion non-equilibrium ring-opening polymerization
The present invention relates to the method that a kind of cyclosiloxane carries out the anion non-equilibrium ring-opening polymerization.
The anionic ring-opening polymerization of general cyclosiloxane is an initiator with potassium hydroxide, sodium hydroxide, Tetramethylammonium hydroxide and tetrabutylammonium hydroxide phosphorus etc., and polyreaction is an equilibrium process, contains 14% siloxanes ring body in the polymerisate.The existence of balanced reaction not only makes the polymerisation conversion of raw material low (~86%), and for the field that needs high purity silicon rubber such as space with and high-performance electronic product silicon rubber, need carry out numerous and diverse operation and remove the siloxanes ring body and just can reach requirement.And the cyclic siloxane anion non-equilibrium polymerization can reduce or eliminate the balanced reaction in the cyclosiloxane polymerization process, and what make the monomer high conversion changes polysiloxane (>95%) into.Therefore, to the research of the anion non-equilibrium ring-opening polymerization of cyclosiloxane, report to some extent successively since 1967 mainly is that research is that initiator causes cyclosiloxane and carries out anionic ring-opening polymerization with the lithium salts.Since lithium salts to anionic activity a little less than, do not interrupt the siloxane bond in the silica chain, thereby there is not balanced reaction in polymerization process.But the cyclic siloxane anion non-equilibrium polymeric research that lithium salts causes is mainly concentrated on active higher hexamethyl cyclotrisiloxane (D
3) monomeric polymerization, and at the lower octamethylcyclotetrasiloxane (D of the activity of the industrial extensive application of organosilicon
4) monomeric polymerization studies then seldom.
This laboratory is once caused cyclosiloxane with the lithium salts of six organic basic ring three silazane and is carried out anionic ring-opening polymerization and prepare star polysiloxane [Chinese patent, application number 98103244.3], but do not relate to lithium salts with the industrial hexamethyldisilazane that obtains easily as initiator, cause the method that cyclosiloxane carries out the anion non-equilibrium ring-opening polymerization.
The present invention has overcome in the prior art when preparing polysiloxane with equilibrium process, and monomer conversion is low, the defective of 14% siloxanes ring body is arranged in polymerisate, and a kind of lithium salts (MM with hexamethyldisilazane is provided
NLi) be initiator, cause the method that the cyclosiloxane ring-opening polymerization prepares high monomer transformation efficiency, highly purified polysiloxane with non-equilibrium polymeric approach, particularly cause octamethylcyclotetrasiloxane (D
4) polymerization have good effect.
Cyclosiloxane ring-opening polymerization among the present invention step is in the following order carried out:
1. prepare MM
NLiThe lithium salts initiator
With MM
NHWith n-Butyl Lithium be in molar ratio: got MM at-60~30 ℃ of following stirring reaction 5-6 hours in 1: 1~1: 1.2
NLiLithium salts, removal of solvent under reduced pressure under the secluding air condition, is carried out thorough washing with normal hexane to the lithium salts that makes, and is neutral until elutant, removal of solvent under reduced pressure again, inflated with nitrogen is protected prepared lithium salts.
Above-mentioned MM
NLiThe lithium salts initiator has following structure:
2. cyclosiloxane anion non-equilibrium ring-opening polymerization:
Add above-mentioned MM in the cyclosiloxane monomer
NLiThe promotor of 2~10 times of molar weights of lithium salts initiator and above-mentioned initiator is carried out body or solution polymerization, and the mol ratio of monomer and initiator is: 10: 1~2000: 1,0 ℃~160 ℃ polyreactions 2~24 hours, obtain polymerisate.
Above-mentioned cyclosiloxane monomer comprises: hexamethyl cyclotrisiloxane (D
3), octamethylcyclotetrasiloxane (D
4), hexaphenyl cyclotrisiloxane (D
3 Ph), tetramethyl-tetrem thiazolinyl cyclotetrasiloxane (D
4 Vi), methyl trifluoro propyl cyclotrisiloxane (D
3 F) or above-mentioned monomeric mixture.
Used promotor comprises: tetrahydrofuran (THF), glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dme, dimethyl sulfoxide (DMSO), dimethyl formamide, hexamethylphosphorictriamide, crown ether, cave ether etc.
The solvent of above-mentioned solution polymerization comprises normal hexane, toluene, the tetrahydrochysene furan food in one's mouth, glycol dimethyl ether etc.
3. functional group's end-blocking of polymkeric substance
The polymerisate of above-mentioned mass polymerization is with normal hexane or toluene dissolving, and adding and initiator equimolar amount or excessive end-capping reagent carry out end-blocking simultaneously.Then can directly add end-capping reagent for solution polymerization and carry out end-blocking, filter after the end capping, filtrate is removal of solvent under reduced pressure again, obtains the polysiloxane product.
Above-mentioned end-capping reagent can be: water, methyl iodide, trimethylchlorosilane, dimethyl vinyl chlorosilane and dimethyl amine alkyl chlorosilane etc.
Polysiloxane with method preparation of the present invention dissolves in organic solvent, and these solvents comprise: alkane, aromatic hydrocarbon, tetrahydrofuran (THF), chloroform.
Silicone monomers transformation efficiency with this method preparation can reach 95-100%; Polymerisate does not contain or only contains a spot of cyclosiloxane, and the highly purified polysiloxane of gained is suitable for using in the field that needs high purity silicon rubber, as space flight, high-performance electronic product scope.
Embodiment
Embodiment 1: in there-necked flask, and logical N
2The deoxygenation dehumidifying.Add hexamethyl cyclotrisiloxane (D
3) 26g, MM
NLiLithium salts 0.01g, tetrahydrofuran (THF) 6ml, 70~80 ℃ of mechanical stirring polymerizations.Finish reaction after 6 hours.
29Si NMR detects D
3100% transforms.With the dissolving of 30ml toluene, carry out end-blocking with 0.5ml water.Filter removal of solvent under reduced pressure, polymkeric substance [η]=43.8ml/g.
Embodiment 2:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
3/ D
4(6%mol.D
3) 15.3g, MM
NLiLithium salts 0.02g, 0.5ml exsiccant N, dinethylformamide are promotor, 100 ℃ of mechanical stirring polymerizations.Viscosity increases after 1 hour, after 4 hours
29Si NMR detects monomer conversion monomer conversion monomer 100% conversion after 95%, 24 hour after 78%, 11 hour.With the dissolving of 20ml toluene, carry out end-blocking with the 1.5ml methyl iodide.Filter removal of solvent under reduced pressure, polymkeric substance [η]=32.06ml/g.
Embodiment 3:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
419.6g, MM
NLiLithium salts 0.02g, 0.5ml exsiccant dimethyl sulfoxide (DMSO) is a promotor, 100 ℃ of mechanical stirring polymerizations.Viscosity obviously increases after 2 hours, after 11 hours
29SiNMR detects monomer conversion and reaches 95%.With the dissolving of 20ml toluene, carry out end-blocking with the 1.5ml trimethylchlorosilane.Filter removal of solvent under reduced pressure, polymkeric substance [η]=82ml/g.
Embodiment 4:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
419.95g, MM
NLiLithium salts 0.08g, 0.5ml exsiccant diethylene glycol dimethyl ether is a promotor, 160 ℃ of mechanical stirring polymerizations.Viscosity obviously increases after 1 hour.After 15 hours
29Si NMR detects monomer conversion 100%.Polymkeric substance [η]=41.87ml/g.
Embodiment 5:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
417.4g, MM
NLiLithium salts 0.87g, 2ml exsiccant triethylene glycol dme is a promotor, 100 ℃ of mechanical stirring polymerizations.Viscosity increases after 2 hours, after 4 hours
29Monomer conversion reached 95% after Si NMR detection monomer conversion reached 91%, 10 hour.Add 20ml toluene dissolve polymer, 1.2ml dimethyl vinyl chlorosilane end-blocking, 25 ℃ were reacted 4 hours, filtered removal of solvent under reduced pressure.Polymkeric substance [η]=9.17ml/g.Embodiment 6:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
4 Vi6.89g, D
45.91g, MM
NLiLithium salts 0.1g, the 12-crown-4 crown ether of 0.5g is a promotor, 60 ℃ of induction stirring polymerizations 20 hours, is warming up to 100 ℃ of polymerizations 10 hours,
29Si NMR detects monomer conversion and reaches 100%.
Embodiment 7:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
3 Ph10.2g, D
33.8gMM
NLiLithium salts 0.05g, 0.1ml exsiccant hexamethylphosphorictriamide is a promotor, and the 30ml normal hexane 40-50 ℃ of induction stirring polymerization 20 hours, filters, and removal of solvent under reduced pressure obtains polymkeric substance.
Embodiment 8:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
3 F12g, MM
NLiLithium salts 0.02g, 20ml exsiccant glycol dimethyl ether is promotor and solvent, 0 ℃ of mechanical stirring polymerization 2 hours, carries out end-blocking with the 1.0ml trimethylchlorosilane.Filter, removal of solvent under reduced pressure obtains polymkeric substance.
Embodiment 9:
In there-necked flask, logical N
2The deoxygenation dehumidifying.Add D
3/ D
4(1%mol.D
3) 15.3g, MM
NLiLithium salts 0.02g, 0.5ml exsiccant dimethyl sulfoxide (DMSO) is a promotor, 100 ℃ of mechanical stirring polymerizations.Monomer conversion monomer 100% conversion after 95%, 24 hour after 11 hours.With the dissolving of 20ml toluene, carry out end-blocking with the 1.5ml methyl iodide.Filter, removal of solvent under reduced pressure obtains polymkeric substance.