RU2697476C1 - Method of producing hydroxyl-containing polymethylsiloxanes - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to methods of producing organosilicon compounds. Disclosed is a method of producing cyclolinear polydimethylsiloxanes containing hydroxyl groups in silicon atoms in a cyclic fragment by reacting α,ω-dichloropolymethylsiloxane with cyclic polyols of general formula [CHSi(O)OH], where n is equal to 4, 6 or 12, in the presence of an acceptor. Molar ratio of reagents ranges from 1:1 to 1:2.EFFECT: method enables controlled modification of polydimethyl siloxane by hydroxyl groups.1 cl, 2 dwg, 1 tbl, 5 ex

Description

The invention relates to the chemical technology of organosilicon compounds, which can be used in the chemical industry to obtain components of new adhesive and protective polymer compositions, in particular, to a method for producing functional polydimethylsiloxanes containing hydroxymethylsiloxane units, the presence of which allows further polymer-analogous transformations to obtain copolymer products .

, Opris, D.M. (2015). Polar-nonpolar interconnected elastic networks with increased permittivity and high breakdown fields for dielectric elastomer transducers. RSC Advances, 5(72), 58428-58438]. Недостатком данного способа является неполная конверсия гидросилильных групп. звестно, что основный гидролиз гидросилильных групп в полиметилгидросилоксане приводит к образованию нерастворимого продукта вследствие совместного протекания процессов гидролиза и конденсации образующихся гидроксильных групп [Cho, Е.С., Chang-Jian, С.W., Chen, Н.С., Chuang, K.S., Zheng, J.Н., Hsiao, Y.S., Lee, K.-C., Huang, J.H. (2017). Robust multifunctional superhydrophobic coatings with enhanced water/oil separation, self-cleaning, anti-corrosion, and anti-biological adhesion. Chemical Engineering Journal, 314, 347-357].Known methods for producing polymethylsiloxanes containing hydroxyl groups at the silicon atom. One of these methods uses hydrolysis of hydrosilyl groups in poly (methylcyanopropyl) methylhydrosiloxane to hydroxyl in the presence of dibutyltin dilaurate [Racks, C., Bele, A., Dascalu, M., Musteata, V.E., Varganici, C.D. , Ionita, D., Vlad S., Cazacu M.,

, Opris, DM (2015). Polar-nonpolar interconnected elastic networks with increased permittivity and high breakdown fields for dielectric elastomer transducers. RSC Advances, 5 (72), 58428-58438]. The disadvantage of this method is the incomplete conversion of hydrosilyl groups. it is known that the main hydrolysis of hydrosilyl groups in polymethylhydrosiloxane leads to the formation of an insoluble product due to the combined processes of hydrolysis and condensation of the resulting hydroxyl groups [Cho, E.S., Chang-Jian, C.W., Chen, N.S., Chuang, KS, Zheng, J.N., Hsiao, YS, Lee, K.-C., Huang, JH (2017). Robust multifunctional superhydrophobic coatings with enhanced water / oil separation, self-cleaning, anti-corrosion, and anti-biological adhesion. Chemical Engineering Journal, 314, 347-357].

A known two-stage method for producing linear polydimethylsiloxanes containing hydroxyl groups on silicon atoms by halogenation of hydrosilyl groups into polydimethyl (hydromethyl) siloxane followed by hydrolysis of the resulting halogen-containing groups. The disadvantage of this approach is the difficulty of monitoring the ongoing reaction processes and the presence of intermolecular and intramolecular condensation of functional groups.

It should be noted that the implementation of selective hydrolysis of functional groups in polymer siloxanes is a difficult task due to the presence of a competing condensation reaction, and in the presence of catalysts, a side process of the cleavage of the siloxane bond. The controlled introduction of hydroxyl groups into the composition of polydimethylsiloxane can be achieved only if it is modified with hydroxyl-containing precursors.

, M.,

, G., Andrianov, K.A., Makarova, N.N., Chernavski, А.I., & Petrov, I.М. (1979). Thermal decomposition of cyclo-linear methylsiloxane polymers. Journal of Organometallic Chemistry, 165(3), 273-279], заключающийся в том что к раствору 1,5-дихлоргексаметилциклотетрасилоксана добавляют смесь α,ω-дигидроксидиметилсилоксанового олигомера (содержащего 4 или 7 диметилсилоксановых звеньев) и пиридина в бензоле, после чего реакционную смесь отмывают, сушат над сульфатом натрия и удаляют растворитель.A known method for producing non-functional polymethylsiloxanes with a linear structure with a chain length of a linear fragment equal to 4 or 7 dimethylsiloxane units and containing 2 dimethylsiloxane units in a cyclic fragment [

, M.,

, G., Andrianov, KA, Makarova, NN, Chernavski, A.I., & Petrov, I.M. (1979). Thermal decomposition of cyclo-linear methylsiloxane polymers. Journal of Organometallic Chemistry, 165 (3), 273-279], in which a mixture of α, ω-dihydroxydimethylsiloxane oligomer (containing 4 or 7 dimethylsiloxane units) and pyridine in benzene is added to a solution of 1,5-dichlorohexamethylcyclotetrasiloxane, followed by reaction the mixture is washed, dried over sodium sulfate and the solvent is removed.

Methods allowing to obtain polymethylsiloxanes of cycllinear structure containing hydroxyl groups on silicon atoms of a cyclic fragment are not described.

The task of the invention is to develop a method for producing polydimethylsiloxanes containing a controlled amount of hydroxyl-containing siloxane units in the chain.

The problem is solved by a new method for producing polydimethylsiloxanes of a cyclolinear structure containing hydroxyl groups on silicon atoms in a cyclic fragment, including the interaction of cyclic polyols of the general formula [(C ₆ H ₅ ) Si (O) OH] _n , where n is 4, 6 or 12 and α , ω-dichloropolydimethylsiloxane, with their molar ratio from 1: 1 to 2: 1, in the presence of an acceptor - pyridine. The general scheme illustrating the production method is presented below:

for a molar ratio of 1/1

for a molar ratio of 2/1

n is 1, 3, 9; m is from 2 to 2500, k can take the value 1 or 2.

Toluene is used as a solvent. The data obtained are presented in the table. Despite the fact that the reaction system is characterized by high functionality, gelation does not occur during the reaction, and the products obtained by the claimed method with a molar ratio of reactants from 1: 1 to 1: 2 are completely soluble in organic solvents. It should be noted that the starting cyclic polyols are insoluble in toluene, while the products formed are completely soluble in it, which indicates the absence of an unreacted cycle in the products.

To quantify the presence of hydroxysilyl groups in the reaction products, they are blocked with vinyl dimethylchlorosilane under conditions that do not violate the product structure (Kalinina, A., Strizhiver, N., Vasilenko, N., Perov, N., Demchenko, N., & Muzafarov, A . (2015). Polycondensation of diethoxydimethylsilane in active medium. Silicon, 7 (2), 95-106.). Then the product is analyzed by GPC and H ¹ NMR spectroscopy.

The absence of changes in the structure of the product is evidenced by the identity of the GPC curves before and after blocking (Fig. 1). In FIG. 1 shows the GPC curves of the starting α, ω-dichloropolydimethylsiloxane (1) and the product obtained in Example 3 before blocking (2) and after blocking (3).

In addition, all products have a molecular weight distribution comparable to the original α, ω-dichloropolydimethylsiloxane, and in the case of a ratio of the starting reagents equal to 1: 1, the formation of a product with a 2-fold increased molecular weight is possible.

The number of hydroxyl groups, which is equivalent to the number of vinylsilyl groups in the polymers after they are blocked by vinyl dimethylchlorosilane, is determined from ¹ H NMR spectroscopy from the ratio of the integral intensities of the protons of vinyl and dimethylsilyl groups in the regions of 6.19-5.67 and 0.4-0.06 ppm, respectively. It turned out that regardless of the length of the initial α, ω-dichloropolydimethylsiloxane and the claimed ratio of the starting reagents, the total amount of hydroxyl groups calculated according to ¹ H NMR spectroscopy coincides with the theoretical one. By way of illustration in FIG. Figure 2 shows a ¹ H NMR spectrum of blocked products obtained in Example 1 (with a reagent ratio of 1: 1) and Example 2 (with a reagent ratio of 2: 1).

The technical result consists in creating a new effective method for producing polydimethylsiloxanes, which allows for the controlled modification of polydimethylsiloxane with hydroxyl groups, while the side gelation processes are excluded.

The synthesis of cyclic polyols is carried out according to a known method [Shchegolikhina, O.I., et al. (2002). Synthesis and properties of stereoregular cyclic polysilanols: cis- [PhSi (O) OH] 4, cis- [PhSi (O) OH] 6, and tris-cis-tris-trans- [PhSi (O) OH] 12. Inorganic chemistry 41 (25), 6892-6904].

The invention is illustrated by the following examples.

Example 1

In a three-necked flask equipped with a magnetic stirrer and a dropping funnel, 107 mg (0.194 mmol) of cis-tetraphenylcyclosiloxane tetraol is dissolved in a mixture of 30 ml of toluene and 15.63 μl (0.194 mmol) of pyridine, after which they are added dropwise before cooling to 0 ° C in an inert atmosphere prepared solution of 5.00 g (0.194 mmol) of α, ω-dichloropolydimethylsiloxane in toluene (20 ml). Then bring the reaction mass to room temperature and boil for 2 hours, then boil another 2 hours. The resulting product is washed in a separatory funnel from pyridine hydrochloride with water to a neutral pH, the resulting polymer solution in toluene is dried over sodium sulfate, and the solvent is removed. Obtain 4.0 g of a viscous product of a milky color. The structure of the obtained reaction product was confirmed using ¹ H and ²⁹ Si NMR spectroscopy. ¹ H NMR, δ _H (CDCl ₃ ): 7.66-7.24 ppm. (5 N, - C ₆ H ₅ ), 0.4-0.14 ppm. (6 H, -Si ((CH ₃ ) ₂ ) -). Si ²⁹ NMR, δ _Si (CDCl ₃ ): 21.95 ppm. (- (CH ₃ ) ₂ Si O _2/2 -), 68.78 ppm (C ₆ H ₅ - Si ( O) -OH), 77.90 ppm (C ₆ H ₅ - Si O _1.5 - (CH ₃ ) ₂ Si O _2/2 -). GPC: Mp = 46500, Mw / Mn = 1.85.

The products in examples 1-5 are synthesized and analyzed as described in example 1. The correlation of proton and silicon signals on H ¹ and Si ²⁹ NMR spectra is carried out as described in example 1.

The data of examples 1-5 are shown in the table.

Blocking of a cyclolineic hydroxyl-containing polymethylsiloxane with vinyl dimethylchlorosilane (general procedure)

To a 10% solution of 1.00 g (7.3 mmol) of ViMe ₂ SiCl in toluene with the addition of an equimolar amount of 0.6 ml (7.3 mmol) of pyridine in an inert atmosphere, a 20% solution of any of the polymers obtained in Examples 1-5 is added dropwise. in toluene weighing 0.5 g, after which the reaction mixture is boiled for 2 hours. The resulting product is washed with water to a neutral pH, dried over anhydrous sodium sulfate, and the solvent is removed. The result is 0.45 g of a blocked polymer. NMR ¹ H, δ _H : 7.66-7.24 ppm. (5 N, - C ₆ H ₅ ), 6.19-5.67 ppm. (m, 3H, -CH = CH ₂ ), 0.4 - 0.06 ppm. (6H, -Si ((CH ₃ ) ₂ ) -). GPC: Mp = 47000, Mw / Mn = 1.86.

Claims (2)

1. A method for producing cyclolinear polydimethylsiloxanes containing hydroxyl groups on silicon atoms in a cyclic fragment, comprising reacting α, ω-dichloropolydimethylsiloxane with cyclic polyols of the general formula [C ₆ H ₅ Si (O) OH] _n , where n is 4, 6 or 12 , with a molar ratio of 1: 1 to 1: 2, in the presence of an acceptor. 2. The method according to p. 1, characterized in that pyridine is used as an acceptor.

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