Polysiloxane containing α-amidoamide structure in side group, and preparation method and application thereof

Abstract

The application provides a polysiloxane containing a side group of an alpha-amidoamide structure and a preparation method and application thereof, the polysiloxane is prepared from a polysiloxane containing a carboxyl side group, a primary amine, a monohydric aldehyde and an isocyanide compound, has a linear structure with a side group of an alpha-amidoamide, the side group includes aliphatic and aromatic groups and the like, and the structure is unique, the polysiloxane containing the side group of the alpha-amidoamide structure can be further crosslinked into a polar organosilicon elastomer as a prepolymer, the glass transition temperature and the dielectric constant of the organosilicon elastomer are obviously improved, meanwhile, the organosilicon elastomer has excellent mechanical properties, has a good application prospect, and further widens the application range of the polysiloxane.

Description

Technical Field

[0001] This invention relates to the field of polysiloxanes, particularly to the field of polysiloxanes containing polar side groups, and specifically to a polysiloxane with an α-acylaminoamide structure in its side group, its preparation and application. Background Technology

[0002] Polysiloxanes are linear polymers with repeating Si-O bonds as the main chain, where the Si atoms have organic groups attached to them. Their general formula is (RmSiO4-m / 2)n, where R can be methyl, vinyl, hydrogen, phenyl, or other groups. The Si-O-Si main chain of polysiloxanes is essentially the same as that of quartz, the difference being the organic groups on the Si atoms. The organic side groups of polysiloxanes are mostly methyl, vinyl, and phenyl. Other side groups are often obtained through reactions of vinyl groups, most commonly hydrosilylation and mercaptoene click reactions. For example, Carmen Racles et al. [Carmen Racles, Mihaela Alexandru, Adrian Bele, et al. Chemical modification of polysiloxanes with polarpendant groups by co-hydrosilylation. RSC Adv., 2014, 4, 37620] synthesized polysiloxanes with cyano side groups via hydrosilylation. Simon JD¨unki et al. [Simon JD¨unki, Martin Tress, Friedrich Kremer, et al. Fine-tuning of the dielectric properties of polysiloxanes by chemical modification. RSC Adv., 2015, 5, 50054] synthesized polysiloxanes with cyano groups on the side group via a mercaptoene click reaction. Yauhen Sheima et al. [Yauhen Sheima, Yulia Yuts, Holger Frauenrath, Dorina M. Opris. Polysiloxanes Modified with Different Types and Contents of Polar Groups: Synthesis, Structure, and Thermal and Dielectric Properties. Macromolecules. 2021, 54(12), 5737-5749] synthesized 13 polysiloxanes with polar side groups via a mercaptoene click reaction. However, polysiloxanes with amide structures on their side groups are rarely reported. Therefore, this invention relates to a polysiloxane with α-acylaminoamide structures on its side groups and its application in dielectric elastomers after preparation and crosslinking. Summary of the Invention

[0003] Based on the above technical background, the inventors made pioneering efforts and discovered that: polysiloxanes prepared using carboxyl-containing polysiloxanes, primary amines, monoaldehydes, and isocyanates as raw materials have a linear structure with α-acylaminoamides as side groups, and also contain the functional groups present in the primary amines, monoaldehydes, and isocyanates, making the molecular design of the polysiloxane more flexible. It can also be used as a prepolymer to prepare organosilicon elastomers through crosslinking. The organosilicon elastomers prepared from it have significantly improved glass transition temperature and dielectric constant, and also have excellent mechanical properties, thus broadening the application range of the polysiloxane, thereby completing the present invention.

[0004] The first aspect of the present invention is to provide a polysiloxane with an α-acylaminoamide structure in the side group, which is prepared by reacting a polysiloxane with a carboxyl group in the side group, a primary amine, a monohydric aldehyde and an isocyanate compound.

[0005] A second aspect of the present invention is to provide a method for preparing a polysiloxane with an α-acylaminoamide structure as described in the first aspect of the present invention, the method comprising the following steps:

[0006] Step 1: Primary amine and monohydric aldehyde are mixed and reacted in a solvent to obtain an intermediate product;

[0007] Step 2: The intermediate product, the polysiloxane with carboxyl groups on the side group, and the isocyanate compound react to obtain the reaction product;

[0008] Step 3: The reaction product is subjected to rotary evaporation, dissolution, precipitation and drying to obtain a polysiloxane with an α-acylaminoamide structure in the side group.

[0009] A third aspect of the present invention is to provide an application of a polysiloxane containing an α-acylaminoamide structure as described in the first aspect of the present invention or a polysiloxane containing an α-acylaminoamide structure prepared by the preparation method described in the second aspect of the present invention, which can be used to prepare organosilicon elastomers.

[0010] A fourth aspect of the present invention is to provide a room-temperature photocurable silicone elastomer, which is prepared from raw materials including polysiloxanes with α-acylaminoamide structures on the side groups as described in the first aspect of the present invention or polysiloxanes with α-acylaminoamide structures on the side groups prepared by the preparation method described in the second aspect of the present invention. Attached Figure Description

[0011] Figure 1 The infrared spectra of the product obtained in Example 1, the dimethylsiloxane-methylvinylsiloxane copolymer, and the polysiloxane with carboxyl groups on the side are shown.

[0012] Figure 2 The 1H NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 1 is shown.

[0013] Figure 3 The carbon NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 1 is shown.

[0014] Figure 4 The infrared spectra of the product obtained in Example 2, the dimethylsiloxane-methylvinylsiloxane copolymer, and the polysiloxane with carboxyl groups on the side are shown.

[0015] Figure 5 The following is a 1H NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 2;

[0016] Figure 6 The following is a carbon NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 2;

[0017] Figure 7 The infrared spectra of the product obtained in Example 3, the dimethylsiloxane-methylvinylsiloxane copolymer, and the polysiloxane with carboxyl groups on the side are shown.

[0018] Figure 8 The following is a 1H NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 3;

[0019] Figure 9 The following is a carbon NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 3;

[0020] Figure 10 The infrared spectra of the product obtained in Example 4 with dimethoxysilane-methylvinylsiloxane copolymer and polysiloxane with carboxyl groups on the side are shown.

[0021] Figure 11 The following is a 1H NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 4;

[0022] Figure 12 The following is a carbon NMR spectrum of the polysiloxane containing an α-acylaminoamide structure in the side group of the product obtained in Example 4;

[0023] Figures 13-16 The DSC spectra of the products obtained in Examples 1 to 4 are shown respectively;

[0024] Figure 17 The dielectric constant test graphs of the elastomer films prepared in Examples 1-4 of the same scale are shown;

[0025] Figure 18 The dielectric constant test graphs of the elastomer films prepared from different proportions of Example 1 are shown;

[0026] Figure 19The stress-strain curves of the elastomeric membranes prepared from different proportions of Example 1 are shown. Detailed Implementation

[0027] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0028] The first aspect of the present invention is to provide a polysiloxane with an α-acylaminoamide structure in the side group, which is prepared by reacting a polysiloxane with a carboxyl group in the side group, a primary amine, a monohydric aldehyde and an isocyanate compound.

[0029] In this invention, the polysiloxane with carboxyl-containing side groups is presumably a random copolymer, whose repeating structural units can be represented by formulas (I-1) and (I-2):

[0030]

[0031] The polysiloxane with carboxyl groups on its side groups is mainly prepared from octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetramethylammonium hydroxide pentahydrate, decamethyltetrasiloxane and 3-mercaptopropionic acid.

[0032] The molar ratio of tetramethylammonium hydroxide pentahydrate, decamethyltetrasiloxane, octamethylcyclotetrasiloxane, 3-mercaptopropionic acid, and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane is (2.5–3) × 10⁻⁶. -3 (14~18)×10 -3 :(2~2.5):(2~3):1, preferably (2.7~2.9)×10 -3 (15~17)×10 -3 :(2.1~2.3):(2.2~2.5):1.

[0033] According to a preferred embodiment of the present invention, the polysiloxane with carboxyl-containing side groups is prepared by the following steps:

[0034] Step a: Octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetramethylammonium hydroxide pentahydrate and decamethyltetrasiloxane are mixed and subjected to vacuum distillation;

[0035] Step b: Add 3-mercaptopropionic acid and 2,2-dimethoxy-2-phenylacetophenone to the product obtained in step a and react them. After post-treatment, a polysiloxane with carboxyl groups on the side group is obtained.

[0036] In this invention, the primary amine compound can be represented by formula (II):

[0037]

[0038] In formula (II), R1 is selected from one or more of alkyl, phenyl, substituted phenyl and allyl groups, wherein the alkyl group is selected from C1 to C2. 16 The alkyl group is preferably selected from C1 to C8 alkyl groups, more preferably from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl. For example, R1 is selected from one or more of n-butyl, p-cyanophenyl and allyl.

[0039] The monohydric aldehyde can be represented by formula (Ⅲ).

[0040]

[0041] In formula (Ⅲ), R2 is selected from one or more of phenyl, substituted phenyl, and allyl groups, wherein the alkyl group is selected from C1 to C2. 16 The alkyl group is preferably selected from C1 to C8 alkyl groups, more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl, for example, R2 is phenyl or n-butyl, and the monohydric aldehyde is selected from one or both of benzaldehyde and n-butyraldehyde.

[0042] Isocyanates can be represented by formula (Ⅳ):

[0043]

[0044] In formula (Ⅳ), R3 is selected from one or more alkyl groups, preferably from one or more of tert-butyl, isopropyl and pentyl, and more preferably, the isocyanate is tert-butyl isocyanate.

[0045] In this invention, the polysiloxane containing an amide structure in the side group is prepared by reacting a polysiloxane containing a carboxyl group in the side group, a primary amine, a monohydric aldehyde, and an isocyanate. First, the primary amine and the monohydric aldehyde undergo a condensation reaction to form an imine. The imine is protonated by the carboxylic acid to form an imine ion. The imine ion undergoes nucleophilic addition with the isocyanate to form a nitrile onion. Then, the carboxylic acid anion attacks the carbon atom of the isocyanate to form another imine intermediate. Finally, rearrangement occurs to generate the final product through acyl transfer.

[0046] The molar ratio of the primary amine, monohydric aldehyde, carboxyl-containing polysiloxane, and isocyanate compound is (0.9–1.5):1:(0.9–1.4):(0.9–1.4), preferably (1–1.3):1:(0.95–1.2):(0.95–1.2), and more preferably (1–1.1):1:1:1.

[0047] The polysiloxane structure contains functional groups from the primary amine, monoaldehyde, and isocyanate compounds, making the molecular design of the polysiloxane more flexible and further expanding its application range.

[0048] The polysiloxane described in this invention is presumably a random copolymer, and its repeating structural units can be represented by formulas (I-1) and (V-2):

[0049]

[0050] In formula (V), R1 and R2 are each independently selected from one or more of alkyl, phenyl, substituted phenyl, and allyl groups, wherein the alkyl group is selected from C1 to C2. 16 The alkyl group is preferably selected from C1 to C8 alkyl groups, and more preferably selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl.

[0051] For example, R1 is selected from one or more of n-butyl, p-cyanophenyl, and allyl, and R2 is phenyl or n-butyl.

[0052] According to a preferred embodiment of the present invention, the polysiloxane containing an α-acylaminoamide structure in its side group has repeating structural units as shown in formulas (I-1), (1), (2), (3), and (4):

[0053]

[0054] The polysiloxane with α-acylaminoamide structure as the side group described in this invention is a linear structure with α-acylaminoamide as the side group. It can be used as a prepolymer for further crosslinking to obtain a polar elastomer, and can significantly improve the glass transition temperature and dielectric constant of the elastomer.

[0055] The polysiloxane with α-acylaminoamide structure in its side group, as described in this invention, has the advantages of high glass transition temperature and high polarity. Its glass transition temperature is -32℃ to -4℃.

[0056] A second aspect of the present invention is to provide a method for preparing a polysiloxane with an α-acylaminoamide structure as described in the first aspect of the present invention, the method comprising the following steps:

[0057] Step 1: Primary amine and monohydric aldehyde are mixed and reacted in a solvent to obtain an intermediate product;

[0058] Step 2: The intermediate product, the polysiloxane with carboxyl groups on the side group, and the isocyanate compound react to obtain the reaction product;

[0059] Step 3: The reaction product is subjected to rotary evaporation, dissolution, precipitation and drying to obtain a polysiloxane with an α-acylaminoamide structure in the side group.

[0060] The following is a detailed description and explanation of this step.

[0061] Step 1: The primary amine and the monohydric aldehyde are mixed and reacted in a solvent to obtain the intermediate product.

[0062] The primary amine is the primary amine described in the first aspect of this invention, and the monoaldehyde is the monoaldehyde described in the first aspect of this invention.

[0063] In this invention, a primary amine undergoes a nucleophilic addition reaction with a monohydric aldehyde. The nitrogen atom with a lone pair of electrons in the primary amine compound attacks the positively charged carbon atom on the carbonyl group of the monohydric aldehyde, completing the nucleophilic addition reaction and forming an intermediate α-hydroxyamine compound, which is then further dehydrated to form a Schiff base.

[0064] The molar ratio of the primary amine to the monohydric aldehyde is (0.9–1.5):1, preferably (1–1.3):1, and more preferably (1–1.1):1.

[0065] The inventors have discovered that the preparation of polysiloxanes with α-acylaminoamide side groups requires strict control of the molar ratio of amino and aldehyde groups. This simplifies the post-processing of polysiloxanes with α-acylaminoamide side groups and results in higher yields and purity.

[0066] The solvent is selected from one or more of liquid aromatics, alcohols, tetrahydrofuran and dioxane, preferably from one or more of toluene, methanol, ethanol, tetrahydrofuran and dioxane, more preferably from one or more of methanol, tetrahydrofuran and toluene, such as methanol.

[0067] In this reaction system, the molar concentration of primary amine and monohydric aldehyde is 0.5–4 mol / L, preferably 1–3 mol / L, and more preferably 2.5–3 mol / L.

[0068] The reaction temperature is 0–50°C, preferably 10–30°C, and more preferably 25°C.

[0069] Step 2: The intermediate product, the polysiloxane with carboxyl groups on the side group, and the isocyanate compound react to obtain the reaction product.

[0070] In step 2, the polysiloxane with carboxyl groups on the side group is the polysiloxane with carboxyl groups on the side group as described in the first aspect of the present invention, and the isocyanate compound is the isocyanate compound as described in the first aspect of the present invention.

[0071] The reaction is carried out in a solvent selected from one or more of liquid aromatics, alcohols, tetrahydrofurans and dioxanes, preferably selected from one or more of toluene, methanol, ethanol, tetrahydrofurans and dioxanes, more preferably selected from one or more of methanol, tetrahydrofurans and toluenes, such as methanol.

[0072] In the reaction system, the molar concentration of the polysiloxane with carboxyl side groups and the isocyanate compound is 1-4 mol / L, preferably 1-2 mol / L, and more preferably 1.5-2 mol / L.

[0073] In this invention, the Schiff base generated in step 1 is protonated by the carboxyl group to form an imine ion. Then, the lone pair nucleophilic carbon of the isocyanate compound attacks the electrophilic center of the imine and reacts with the carboxyl group as an electrophilic reagent. Subsequently, the intramolecular Mumm rearrangement forms an α-acylaminoamide structure.

[0074] The molar ratio of the monohydric aldehyde, the polysiloxane with carboxyl side groups, and the isocyanate compound is 1:(0.9-1.4):(0.9-1.4), preferably 1:(0.95-1.2):(0.95-1.2), and more preferably 1:1:1.

[0075] Using the above molar ratio of raw materials can result in high yield and purity of the final product, and simplify the post-processing.

[0076] The reaction temperature is 0–60°C, preferably 10–40°C, and more preferably 25°C.

[0077] The reaction time is 12 to 36 hours, preferably 12 to 24 hours.

[0078] After the addition of the isocyanate, the reaction system changes rapidly and tends to stabilize within a short time. The reaction time can be adjusted according to the actual situation of the reaction, preferably within the range mentioned above.

[0079] According to a preferred embodiment of the present invention, the polysiloxane with carboxyl-containing side groups is prepared by the following steps:

[0080] Step a: Octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetramethylammonium hydroxide pentahydrate and decamethyltetrasiloxane are mixed and subjected to vacuum distillation;

[0081] Step b: Add 3-mercaptopropionic acid and 2,2-dimethoxy-2-phenylacetophenone to the product obtained in step a and react them. After post-treatment, a polysiloxane with carboxyl groups on the side group is obtained.

[0082] In step a, the molar ratio of tetramethylammonium hydroxide pentahydrate, decamethyltetrasiloxane, octamethylcyclotetrasiloxane, and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane is (2.5–3) × 10⁻⁶. -3 (14~18)×10 -3 :(2~2.5):1, preferably (2.7~2.9)×10 -3 (15~17)×10 -3 :(2.1~2.3):1.

[0083] The vacuum distillation temperature is 40–50℃, preferably 42–47℃, and the vacuum distillation time is 20–45 min, preferably 25–40 min. The purpose of vacuum distillation is to remove trace amounts of water from the reaction system. Mechanical stirring is performed after vacuum distillation.

[0084] The reaction is preferably carried out under a nitrogen atmosphere, at 90–120°C for 2–5 h, and then at 110–160°C for 0.5–3 h. More preferably, the reaction is carried out at 105–115°C for 3–5 h, and then at 150–160°C for 0.5–2 h.

[0085] After the reaction, vacuum distillation is carried out at a temperature of 160–180°C, preferably 170°C, for a time of 2–4 hours, preferably 3 hours.

[0086] In step b, the molar ratio of the product obtained in step a, 3-mercaptopropionic acid, and 2,2-dimethoxy-2-phenylacetophenone is (90-100):(150-160):1, preferably (95-100):(150-155):1.

[0087] After the product obtained in step a and 3-mercaptopropionic acid are dissolved in a solvent, 2,2-dimethoxy-2-phenylacetophenone is added to it. The solvent is preferably tetrahydrofuran.

[0088] The reaction was carried out under ultraviolet light irradiation, with magnetic stirring during the process, and the reaction time was 15-30 minutes.

[0089] The post-treatment includes rotary evaporation, dissolving the precipitate, and drying. Rotary evaporation is used to remove most of the solvent. After rotary evaporation, the product is placed in deionized water to precipitate, and the precipitate is collected and dissolved in a solvent, preferably tetrahydrofuran.

[0090] The process of dissolving and precipitating is repeated multiple times until a product of high purity is obtained.

[0091] The drying temperature is preferably 50–65°C. This yields a polysiloxane with carboxyl groups on its side groups.

[0092] Step 3: The reaction product is subjected to rotary evaporation, dissolution, precipitation and drying to obtain a polysiloxane with an α-acylaminoamide structure in the side group.

[0093] The reaction products obtained in step 2 include polysiloxanes with α-acylaminoamide side groups, as well as other byproducts and impurities. To obtain the target product with high purity, post-treatment of the reaction is required, including rotary evaporation, dissolution and precipitation, and drying. Rotary evaporation is used to remove most of the solvent.

[0094] During the experiment, it was found that polysiloxanes with α-acylaminoamide structures on the side groups can dissolve in solvents, such as methanol. Therefore, the solvent needs to be removed by rotary evaporation in the post-processing.

[0095] After removing the solvent, dissolution and precipitation are required to improve the purity of the product. Dissolution is preferably carried out in tetrahydrofuran, and precipitation is preferably carried out in cyclohexane. Dissolution and precipitation can remove small molecules in the product and improve the purity of the target product.

[0096] The drying process is preferably vacuum drying, with a drying temperature of 30–70°C, more preferably 40–65°C, and even more preferably 60°C.

[0097] The yield of the final product, polysiloxane with α-acylaminoamide structure in the side group, reached over 80%, even up to 85%.

[0098] A third aspect of the present invention is to provide an application of a polysiloxane containing an α-acylaminoamide structure as described in the first aspect of the present invention or a polysiloxane containing an α-acylaminoamide structure prepared by the preparation method described in the second aspect of the present invention, which can be used to prepare organosilicon elastomers.

[0099] The organosilicon elastomer prepared using this polysiloxane exhibits significantly improved polarity, glass transition temperature, and dielectric constant, while also possessing excellent mechanical properties, showing promising application prospects.

[0100] A fourth aspect of the present invention is to provide a room-temperature photocurable silicone elastomer, which is prepared from raw materials including polysiloxanes with α-acylaminoamide structures on the side groups as described in the first aspect of the present invention or polysiloxanes with α-acylaminoamide structures on the side groups prepared by the preparation method described in the second aspect of the present invention.

[0101] Experiments have shown that the addition of polysiloxanes with α-acylaminoamide structures in their side groups increases the dielectric constant of silicone elastomers while decreasing their modulus.

[0102] The polysiloxane containing α-acylaminoamide structure in its side group accounts for 10% to 90% of the mass of the raw material, preferably 10% to 80% by mass.

[0103] Since the polysiloxane with α-acylaminoamide structure on the side group contains a large number of hydrogen bonds, its addition to silicone rubber helps to improve the mechanical properties of silicone rubber. Therefore, the organosilicon elastomer of the present invention not only has a high dielectric constant, but also has excellent mechanical properties.

[0104] In this invention, the light transmittance of silicone rubber obtained by adding polysiloxanes with α-acylaminoamide side groups to the raw materials generally decreases. This may be because phase separation occurs after polar and non-polar polysiloxanes are mixed, resulting in a relatively disordered arrangement of polymer molecules and thus a decrease in the light transmittance of the material.

[0105] The raw materials for preparing this room temperature photocurable silicone elastomer also include a crosslinking agent, a UV photoinitiator, and a methyl vinyl-dimethylsiloxane copolymer.

[0106] The crosslinking agent is preferably pentaerythritol tetrakis(3-mercaptopropionic acid) ester, and the ultraviolet photoinitiator is preferably 2,2-dimethoxy-2-phenylacetophenone.

[0107] The glass transition temperature of this silicone elastomer is -112.7 to -13.7℃, and its dielectric constant at 0.1 Hz is 3.3 to 18, 10. 3 The dielectric constant of Hz is 3.2–4.7, 10 6 The dielectric constant of Hz is 3.1 to 3.7.

[0108] The beneficial effects of this invention are as follows:

[0109] (1) The polysiloxane with α-acylaminoamide structure in the side group of the present invention has a linear structure, including a diamide structure and a variety of functional groups, and has a unique and novel structure.

[0110] (2) The polysiloxane with α-acylaminoamide structure in the side group described in this invention can effectively improve the glass transition temperature and dielectric constant of materials such as organosilicon elastomers, and has potential application value, further broadening the application range of polysiloxane;

[0111] (3) The polysiloxane with α-acylaminoamide structure in the side group of the present invention has a lower modulus and a higher elongation at break after being added to the organosilicon elastomer.

[0112] (4) The preparation method of the polysiloxane with α-acylaminoamide structure in the side group of the present invention is simple, has high reaction efficiency, mild conditions and is easy to implement.

[0113] Example

[0114] The present invention is further illustrated by specific examples below. These embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0115] Example 1

[0116] 33.40 g (0.11 mol) of octamethylcyclotetrasiloxane (D4) and 16.60 g (0.05 mol) of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4) were added to a 250 mL reaction flask. Then, 0.025 g (0.14 mmol) of tetramethylammonium hydroxide pentahydrate and 0.25 g (0.80 mmol) of decamethyltetrasiloxane were added. The mixture was then distilled under reduced pressure at 45 °C for 30 min. After that, the reaction was carried out at 110 °C for 4 h under mechanical stirring and a nitrogen atmosphere. The temperature was then raised to 150 °C and held for 1 h. Finally, the mixture was distilled under reduced pressure at 170 °C for 3 h to obtain PDMS-co-PMVS.

[0117] 20 g (approximately 0.077 mol of vinyl groups) of PDMS-co-PMVS and 12.31 g (approximately 0.12 mol of mercapto groups, 1.5 eq of vinyl groups) of 3-mercaptopropionic acid were dissolved in 100 mL of tetrahydrofuran. Then, 0.2 g of photoinitiator 2,2-dimethoxy-2-phenylacetophenone was added. The mixture was magnetically stirred under a 365 nm UV lamp for 20 min. After the reaction was complete, most of the solvent was removed by rotary evaporation. The product was then precipitated in deionized water. The precipitate was collected, dissolved in tetrahydrofuran, and then precipitated again in deionized water. This process was repeated several times until a satisfactory purity was achieved. Finally, the product was dried in an oven at 60 °C to obtain PDMS-g-COOH.

[0118] 5 g (approximately 0.014 mol carboxyl groups) of PDMS-g-COOH was dissolved in methanol for later use. Then, 1.454 g (0.014 mol) of benzaldehyde and 0.782 g (0.014 mol) of allylamine were dissolved in 5 mL of methanol and reacted at room temperature for 30 min. After that, 1.139 g (0.014 mol) of tert-butyl isocyanate and a methanol solution of PDMS-g-COOH were added, and the mixture was reacted at room temperature for 24 h.

[0119] After the reaction was complete, most of the solvent was removed by rotary evaporation, and the product was then precipitated in cyclohexane. The precipitate was collected, dissolved in tetrahydrofuran, and then precipitated in cyclohexane. This process was repeated several times until a satisfactory purity was achieved. Finally, the product was dried in an oven at 60°C. A polysiloxane with an α-acylaminoamide structure in the side group was obtained and named PDMS-g-(All,Ph,tBu).

[0120] The proton NMR spectrum of PDMS-g-(All,Ph,tBu) was measured, and the results are as follows: Figure 2 As shown.

[0121] from Figure 2As can be seen, the product structure includes an allyl group, a benzene ring, a tert-butyl group, and a proton H on the diamide. Here, m represents the proton H on the tert-butyl group, f, g, h, and i represent the proton H on the allyl group, k represents the proton H on the benzene ring, and l represents the proton H on the diamide. The chemical shifts are Hf (δ = 3.94 ppm), Hh, i (δ = 4.80-4.91 ppm), Hg (δ = 5.36 ppm), Hk (δ = 7.30 ppm), Hl (δ = 7.80 ppm), and Hm (δ = 1.23 ppm), respectively.

[0122] The final product PDMS-g-(All,Ph,tBu) was subjected to carbon NMR spectroscopy, and the results are as follows: Figure 3 As shown.

[0123] from Figure 3 As can be seen, the product structure includes allyl, benzene ring, tert-butyl, and C on the amide. h, k, and o are C on the allyl group, l, m, n, and p are C on the benzene ring, f and i are C on the tert-butyl group, and q and r are C on the diamide and triamide, respectively. The chemical shifts are Ch (δ = 47.89 ppm), Ck (δ = 115.59 ppm), Co (δ = 136.06 ppm), Cl (δ = 128.01 ppm), Cm (δ = 128.70 ppm), Cn (δ = 129.31 ppm), Cp (δ = 137.54 ppm), Cf (δ = 28.80 ppm), Ci (δ = 50.77 ppm), Cq (δ = 169.22 ppm), and Cr (δ = 172.17 ppm).

[0124] Further analysis using 1H and 1C NMR spectra revealed that the side groups of the repeating polysiloxane structural unit contain amide structures.

[0125] Example 2

[0126] The preparation was carried out in a similar manner to Example 1, except that: 5 g (approximately 0.014 mol of carboxyl groups) of PDMS-g-COOH was dissolved in methanol for later use, and then 1.454 g (0.014 mol) of benzaldehyde and 1.002 g (0.014 mol) of n-butylamine were dissolved in 5 mL of methanol and reacted at room temperature for 30 min. A polysiloxane with an α-acylaminoamide structure as a side group was obtained, named PDMS-g-(nBu,Ph,tBu).

[0127] The proton NMR spectrum of PDMS-g-(nBu,Ph,tBu) was measured, and the results are as follows: Figure 5 As shown.

[0128] from Figure 5As can be seen, the product structure includes protons H on the n-butyl, benzene ring, and tert-butyl groups. The proton H on the diamide is not observable in deuterated chloroform. Here, m represents the proton H on the tert-butyl group, f, g, h, and i represent the proton H on the n-butyl group, k represents the proton H on the benzene ring, and l represents the proton H on the diamide. The chemical shifts are Hf (δ = 3.30 ppm), Hh (δ = 1.08 ppm), Hi (δ = 0.73 ppm), Hg (δ = 1.39 ppm), Hk (δ = 7.35–7.39 ppm), and Hm (δ = 1.35 ppm), respectively.

[0129] The PDMS-g-(nBu,Ph,tBu) was subjected to carbon NMR spectroscopy, and the results are as follows: Figure 6 As shown.

[0130] from Figure 6 As can be seen, the product structure includes C on the n-butyl group, benzene ring, tert-butyl group, and amide. Specifically, c, e, s, and j are C on the n-butyl group, m, n, o, and p are C on the benzene ring, k and h are C on the tert-butyl group, and q and r are C on the secondary and tert-amide groups, respectively. The chemical shifts are Cc (δ = 13.48 ppm), Ce (δ = 20.01 ppm), Cs (δ = 31.83 ppm), Cj (δ = 46.65 ppm), Cm (δ = 128.29 ppm), Cn (δ = 128.65 ppm), Co (δ = 129.44 ppm), Cp (δ = 135.75 ppm), Ck (δ = 51.52 ppm), Ch (δ = 28.63 ppm), Cq (δ = 169.14 ppm), and Cr (δ = 172.18 ppm).

[0131] Further analysis using 1H and 1C NMR spectra revealed that the side groups of the repeating polysiloxane structural unit contain amide structures.

[0132] Example 3

[0133] The preparation was carried out in a similar manner to Example 1, except that: 5 g (approximately 0.014 mol of carboxyl groups) of PDMS-g-COOH was dissolved in methanol for later use, and then 0.988 g (0.014 mol) of n-butyraldehyde and 1.002 g (0.014 mol) of n-butylamine were dissolved in 5 mL of methanol and reacted at room temperature for 30 min. A polysiloxane with an α-acylaminoamide structure as a side group was obtained, named PDMS-g-(All,nPr,tBu).

[0134] The proton NMR spectrum of PDMS-g-(All,nPr,tBu) was measured, and the results are as follows: Figure 8 As shown.

[0135] from Figure 8As can be seen, the product structure includes protons H on the allyl, n-propyl, and tert-butyl groups. The proton H on the diamide is not observable in deuterated chloroform. Here, o represents the proton H on the tert-butyl group, f, g, h, and i represent the proton H on the allyl group, and k, l, and m represent the proton H on the n-propyl group. The chemical shifts are Hf (δ = 3.98 ppm), Hh, i (δ = 5.17-5.21 ppm), Hg (δ = 5.75 ppm), Hk (δ = 1.54 ppm), Hl (δ = 1.27 ppm), Hm (δ = 0.88 ppm), and Ho (δ = 1.32 ppm), respectively.

[0136] The PDMS-g-(All,nPr,tBu) was subjected to carbon NMR spectroscopy, and the results are as follows: Figure 9 As shown.

[0137] Figure 9 The product structure includes C atoms on allyl, n-propyl, tert-butyl, and amide groups. n, o, and k represent C atoms on the allyl group; c, d, and j represent C atoms on the n-propyl group; h and l represent C atoms on the tert-butyl group; and p and q represent C atoms on the secondary and tert-amide groups, respectively. The chemical shifts are Cn (δ = 116.89 ppm), Co (δ = 134.26 ppm), Ck (δ = 46.80 ppm), Cc (δ = 13.90 ppm), Cd (δ = 18.34 ppm), Cj (δ = 33.75 ppm), Ch (δ = 28.64 ppm), Cl (δ = 51.10 ppm), Cp (δ = 169.88 ppm), and Cq (δ = 173.28 ppm).

[0138] Further analysis using 1H and 1C NMR spectra revealed that the side groups of the repeating polysiloxane structural unit contain amide structures.

[0139] Example 4

[0140] The preparation was carried out in a similar manner to Example 1, except that: 5 g (approximately 0.014 mol of carboxyl groups) of PDMS-g-COOH was dissolved in methanol for later use, and then 1.454 g (0.014 mol) of benzaldehyde and 1.618 g (0.014 mol) of aminobenzonitrile were dissolved in 5 mL of methanol and reacted at room temperature for 30 min. A polysiloxane with an α-acylaminoamide structure as a side group was obtained, named PDMS-g-(pCyanoPh,nPr,tBu).

[0141] The proton NMR spectrum of PDMS-g-(pCyanoPh,nPr,tBu) was measured, and the results are as follows: Figure 11 As shown.

[0142] Figure 11As can be seen, the product structure includes protons H on the p-cyanophenyl, n-propyl, and tert-butyl groups. The proton H on the diamide is not observable in deuterated chloroform. Here, l represents the proton H on the tert-butyl group, f and g represent the proton H on the allyl group, and i, j, and k represent the proton H on the n-propyl group. The chemical shifts are Hl (δ = 1.39 ppm), Hf (δ = 7.45 ppm), Hg (δ = 7.72 ppm), Hi (δ = 1.45 ppm), Hj (δ = 1.30 ppm), and Hk (δ = 0.86 ppm), respectively.

[0143] The PDMS-g-(pCyanoPh,nPr,tBu) was subjected to carbon NMR spectroscopy, and the results are as follows: Figure 12 As shown.

[0144] Figure 12 The product structure includes C atoms on the p-cyanophenyl, n-propyl, tert-butyl, and amide groups. Here, m, n, o, p, and q represent the C atom on the p-cyanophenyl group, c, d, and j represent the C atom on the n-propyl group, h and k represent the C atom on the tert-butyl group, and r and s represent the C atoms on the secondary and tert-amide groups, respectively. The chemical shifts are Cm (δ = 112.72 ppm), Cn (δ = 117.82 ppm), Co (δ = 130.75 ppm), Cp (δ = 133.23 ppm), Cq (δ = 143.03 ppm), Cc (δ = 13.86 ppm), Cd (δ = 18.23 ppm), Cj (δ = 35.02 ppm), Ch (δ = 28.64 ppm), Ck (δ = 51.35 ppm), Cr (δ = 169.52 ppm), and Cs (δ = 171.64 ppm).

[0145] Further analysis using 1H and 1C NMR spectra revealed that the side groups of the repeating polysiloxane structural unit contain amide structures.

[0146] Experimental Example

[0147] Experiment Example 1: Infrared Spectroscopy Test

[0148] Infrared spectroscopy was performed on the PDMS-co-PMVS, PDMS-g-COOH, and the obtained polysiloxane prepared in Example 1. The resulting infrared spectra are shown below. Figure 1 As shown. Infrared spectroscopy was performed on the PDMS-co-PMVS, PDMS-g-COOH, and the obtained polysiloxane prepared in Example 2. The resulting infrared spectra are shown below. Figure 4 As shown. Infrared spectroscopy was performed on the PDMS-co-PMVS, PDMS-g-COOH, and the obtained polysiloxane prepared in Example 3. The resulting infrared spectra are shown below. Figure 7 As shown. Infrared spectroscopy was performed on PDMS-co-PMVS, PDMS-g-COOH, and the obtained polysiloxane prepared in Example 4. The resulting infrared spectra are shown below. Figure 10 As shown.

[0149] from Figure 1 As can be seen from the infrared curves, compared with those of PDMS-co-PMVS and PDMS-g-COOH, the infrared curve of the polysiloxane prepared in Example 1 is located at 3328 cm⁻¹. -1 The NH stretching vibration peak at 1684 cm⁻¹ -1 The peak of the NHC=O stretching vibration is at 1629 cm⁻¹. -1 The NC=O stretching vibration peak and 1547cm -1 The presence of the NH deformation vibration peak indicates that the prepared polysiloxane contains an amide structure.

[0150] Figure 4 It can be clearly seen that it is located at 3329cm. -1 The NH stretching vibration peak at 1685 cm⁻¹ -1 The peak of the stretching vibration of NHC=O is 1626 cm⁻¹. -1 The NC=O stretching vibration peak and 1548 cm⁻¹ -1 The presence of the NH deformation vibration peak indicates that the prepared polysiloxane contains an amide structure.

[0151] Figure 7 The height is 3326cm. -1 The NH stretching vibration peak at 1681 cm⁻¹ -1 The stretching vibration peak of NHC=O at 1629 cm⁻¹ -1 The NC=O stretching vibration peak and 1539 cm⁻¹ -1 The presence of the NH deformation vibration peak indicates that the polysiloxane prepared in Example 3 contains an amide structure.

[0152] Figure 10 The middle is located at 3353cm -1 It has an NH stretching vibration peak at 1673 cm⁻¹. -1 It has an NHC=O stretching vibration peak at 1604 cm⁻¹. -1 The NC=O stretching vibration peak and 1518 cm⁻¹ -1 NH deformation vibration peak, 2214 cm -1 The presence of the CN stretching vibration peak indicates that the polysiloxane prepared in Example 4 contains an amide structure.

[0153] Experimental Example 2: DSC Test

[0154] Differential scanning calorimetry (DSC) was performed on PDMS-co-PMVS and the polysiloxanes prepared in Examples 1-4, with a heating rate of 20 °C / min (DSC: NETZSCH DSC 200F3, GE, Germany, N2 atmosphere). The DSC test results are as follows: Figures 13-16 The results (with the upward peak representing the endothermic phase) and DSC test data are shown in Table 1. Figure 13 The image in the small box at the top left is the DSC spectrum of PDMS-co-PMVS.

[0155] from Figures 13-16 As can be seen from Table 1, the glass transition temperature of polysiloxanes is significantly increased after the side groups are equipped with α-acylaminoamide structures. Compared with ungrafted polysiloxanes, the glass transition temperature of polysiloxane in Example 1 is increased by 117.2℃, that in Example 2 by 114.4℃, that in Example 3 by 90.4℃, and that in Example 4 by 110.2℃.

[0156] Table 1

[0157]

[0158]

[0159] Experiment Example 3: Dielectric Constant Test

[0160] Organosilicon elastomer films were prepared from the polysiloxanes with α-acylaminoamide structures obtained in Examples 1, 2, 3, and 4, respectively. The specific preparation process is as follows: 1 mol% vinyl content polysiloxane was dissolved in a small amount of tetrahydrofuran, and then polysiloxane with α-acylaminoamide structures was added to it. Based on the weight of the methyl vinyl-dimethylsiloxane copolymer and the polysiloxane with α-acylaminoamide structures being 100%, the amount of polysiloxane with α-acylaminoamide structures added was 40% (40% by weight can also be recorded as 40 wt%). Among them, the mass of polysiloxane with α-acylaminoamide structures was 2 g, and the mass of 1 mol% vinyl content polysiloxane was 3 g, for a total of 5 g.

[0161] Then add 50 mg of crosslinking agent pentaerythritol tetrakis(3-mercaptopropionic acid) and 25 mg of ultraviolet photoinitiator 2,2-dimethoxy-2-phenylacetophenone, and mix for 30 min under high speed stirring to obtain casting solution;

[0162] Then pour the solution into a mold with a transparent FEP film at the bottom, remove air bubbles three times in a vacuum drying oven, then cover the top with a layer of transparent FEP film and press it to a thickness of 0.5 mm with a flat metal plate.

[0163] The pressed silicone rubber was placed under a 365nm ultraviolet lamp and irradiated for 5 minutes on each side. Finally, the FEP film was peeled off, and the elastomer film was dried in an oven at 60°C for 24 hours. The silicone elastomer films prepared according to Examples 1 to 4 were respectively designated as 40wt% PDMS-g-(All,Ph,tBu), 40wt% PDMS-g-(nBu,Ph,tBu), 40wt% PDMS-g-(All,nPr,tBu), and 40wt% PDMS-g-(pCyanoPh,nPr,tBu).

[0164] Its dielectric properties were tested (using a broadband dielectric impedance spectrometer: model Concept 50, Novocontrol GmbH, Germany, at room temperature), and the dielectric constant test results are as follows: Figure 17 As shown in Table 2.

[0165] Table 2

[0166] sample 0.1Hz <![CDATA[10 3 Hz]]> <![CDATA[10 6 Hz]]> 100wt% PDMS-co-PMVS 2.9 2.9 3.0 40wt% PDMS-g-(All, Ph, tBu) 3.9 3.5 3.1 40wt% PDMS-g-(nBu,Ph,tBu) 8.06 3.81 3.03 40wt% PDMS-g-(All,nPr,tBu) 8.50 3.69 3.25 40wt%PDMS-g-(pCyanoPh,nPr,tBu) 17.84 4.48 3.06

[0167] From Table 2 and Figure 17 As can be seen, the dielectric constant of the elastomer film was improved after adding 40 wt% of the elastomers of Examples 1-4 respectively. Among them, the dielectric constant of the elastomer film was improved the most after adding the elastomer of Example 4, which was 14.94 higher than that of the unmodified silicone rubber at 0.1 Hz. The dielectric constant of the other three elastomers was also improved to varying degrees after adding them.

[0168] Elastomer films containing 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, and 80 wt% of PDMS-g-(All,Ph,tBu) prepared in Example 1 were prepared according to the above method. The dielectric constants of these films were then tested at room temperature using a broadband dielectric impedance spectrometer: Concept 50, Novocontrol GmbH, Germany. The dielectric constant test results are as follows: Figure 18 As shown in Table 3.

[0169] Table 3

[0170] sample 0.1Hz <![CDATA[10 3 Hz]]> <![CDATA[10 6 Hz]]> 100wt% PDMS-co-PMVS 2.9 2.9 3.0 10wt% PDMS-g-(All, Ph, tBu) 3.3 3.2 3.0 20wt% PDMS-g-(All, Ph, tBu) 3.5 3.3 3.1 30wt% PDMS-g-(All, Ph, tBu) 4.0 3.4 3.1 40wt% PDMS-g-(All, Ph, tBu) 3.9 3.5 3.1 50wt% PDMS-g-(All, Ph, tBu) 4.9 4.2 3.5 60wt% PDMS-g-(All, Ph, tBu) 5.5 3.9 3.3 80wt% PDMS-g-(All, Ph, tBu) 6.2 4.7 3.7

[0171] From Table 3 and Figure 18As can be seen, the elastomer prepared by the present invention using polysiloxanes with α-acylaminoamide structures in the side groups has a higher dielectric constant than the elastomer prepared by polysiloxanes without side groups. Furthermore, the dielectric constant of the elastomer gradually increases with the increase of the content of polysiloxanes with α-acylaminoamide structures in the side groups.

[0172] Experiment Example 4 Mechanical Property Testing

[0173] Tensile tests were conducted on elastomers with different contents of PDMS-g-(All,Ph,tBu) using a Sansi universal testing machine at a tensile speed of 500 mm / min. The stress-strain curves are shown below. Figure 19 As shown.

[0174] from Figure 19 As can be seen, with the increase of PDMS-g-(All,Ph,tBu) content, the modulus of the elastomer gradually decreases and the elongation at break increases.

[0175] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A polysiloxane with an α-acylaminoamide structure as a side group, characterized in that, This polysiloxane is prepared by reacting a polysiloxane with carboxyl-containing side groups, a primary amine, a monohydric aldehyde, and tert-butyl isocyanate. The polysiloxane with carboxyl groups on its side groups is mainly prepared from octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetramethylammonium hydroxide pentahydrate, decamethyltetrasiloxane and 3-mercaptopropionic acid. The primary amine can be represented by formula (II): Formula (II); R1 is selected from one or more of alkyl, phenyl, substituted phenyl, and allyl groups. A monohydric aldehyde can be represented by formula (Ⅲ). Formula (Ⅲ); R2 is selected from one or more of phenyl, substituted phenyl, and allyl groups.

2. The polysiloxane according to claim 1, characterized in that, In formula (II), the alkyl group is selected from C1 to C2. 16 Alkyl groups.

3. The polysiloxane according to claim 1, characterized in that, In formula (II), the alkyl group is selected from C1 to C8 alkyl groups.

4. The polysiloxane according to claim 1, characterized in that, The monoaldehyde is selected from one or both of benzaldehyde and n-butyraldehyde.

5. The polysiloxane according to claim 1, characterized in that, The glass transition temperature of the polysiloxane containing an α-acylaminoamide structure in its side group is -32℃ to -4℃.

6. A method for preparing a polysiloxane with an α-acylaminoamide structure as a side group according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: Step 1: Primary amine and monohydric aldehyde are mixed and reacted in a solvent to obtain an intermediate product; Step 2: The intermediate product, the polysiloxane with carboxyl groups on the side group, and tert-butyl isocyanate react to obtain the reaction product; Step 3: The reaction product is subjected to rotary evaporation, dissolution, precipitation and drying to obtain a polysiloxane with an α-acylaminoamide structure in the side group.

7. The preparation method according to claim 6, characterized in that, In step 1, The reaction temperature is 0–50°C.

8. The preparation method according to claim 6, characterized in that, In step 1, the reaction temperature is 10–30°C.

9. The preparation method according to claim 6, characterized in that, In step 2, the polysiloxane with carboxyl-containing side groups is prepared through the following steps: Step a: Octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetramethylammonium hydroxide pentahydrate and decamethyltetrasiloxane are mixed and subjected to vacuum distillation; Step b: Add 3-mercaptopropionic acid and 2,2-dimethoxy-2-phenylacetophenone to the product obtained in step a and react them. After post-treatment, a polysiloxane with carboxyl groups on the side group is obtained.

10. The use of a polysiloxane containing an α-acylaminoamide structure as described in any one of claims 1 to 5, or a polysiloxane containing an α-acylaminoamide structure prepared by any one of claims 6 to 9, for the preparation of organosilicon elastomers.

11. A room temperature photocurable silicone elastomer, characterized in that, The organosilicon elastomer is prepared from raw materials including polysiloxanes with α-acylaminoamide structures as described in any one of claims 1 to 5, or polysiloxanes with α-acylaminoamide structures as described in any one of claims 6 to 9.

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