Room temperature self-repairable silicone elastomer, method of making and metal-coordinated silicone elastomer

Abstract

The application discloses a room-temperature self-repairable organic silicon elastomer, a preparation method and a metal-coordinated organic silicon elastomer. The preparation method comprises the following steps: S1, dissolving a silicon rubber and a diaryl ethylene derivative in a first solvent, and reacting to obtain a first product; and S2, adding a difunctional isocyanate into the first product, and reacting to obtain the room-temperature self-repairable organic silicon elastomer. The prepared organic silicon elastomer has excellent light response performance and light healing performance, can realize self-healing at room temperature, and can be repeatedly processed. On one hand, only one light source is used in the self-healing process, which is convenient for practical application. On the other hand, the self-healing can be realized in a short time, and the self-healing efficiency is significantly improved. In addition, the prepared metal-coordinated organic silicon elastomer also has excellent mechanical performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone polymers, and further relates to a room-temperature self-repairable silicone elastomer, a preparation method and a metal-coordinated silicone elastomer. BACKGROUND

[0002] Polymers with self-repairing properties have attracted much attention due to their ability to enhance the durability, functionality and reliability of materials in practical applications. In recent years, many polymers with self-healing properties have been developed and reported. In particular, photo-responsive self-healing. Using light as a stimulus, it can be applied locally to damaged areas and provides the possibility of healing under harsh conditions (e.g. water and conditions below zero). A Self-repairing transparent film with reprocessable, ultra-high strength and outstanding elasticity based on interlocking hydrogen bonds and reversible topological networks [Chemical Engineering Journal 456 (2023)] discloses a poly(thiourethane-urea) (PTUU) film with interlocking hydrogen bonds (IHB) and reversible topological networks. IHB endows the film with high tensile strength (61.6 MPa) and scratch resistance, but the self-repairing performance of the PTUU film decreases, and high temperature is required to drive self-repairing, which is more demanding than materials that can self-repair at room temperature.

[0003] A photoresponsive azopyridine-based supramolecular elastomer for self-healing strain sensors [Chemical Engineering Journal 395 (2020))] discloses a metal supramolecular elastomer containing azopyridine, which realizes the possibility of photorepairing under mild conditions. Azopyridine not only has the common characteristics of azo that can exhibit photoisomerization ability, but also the pyridine group can coordinate with transition metal ions and lanthanide ions in self-healing polymers, such as iron, zinc and europium, to realize dynamic optical recovery based on metal-ligand systems. During the photorepairing process, the cleavage and renewal of coordination bonds occur simultaneously when the cut surface is irradiated with 365 nm and 450 nm light sources, respectively. In the repair test, the samples show healing behavior after 90 min (365 nm) and 20 min (450 nm) of irradiation treatment, respectively. The healing rate is 100% after 24 h of room temperature repair, while only 46.1% efficiency can be achieved within 12 h.

[0004] Although the metal supramolecular elastomer containing azopyridine can realize photorepairing at room temperature, the stability of azo-based polymers is weak, which has a certain influence on the metal supramolecular elastomer containing azopyridine. And the healing process needs to use two light sources of 365 nm and 450 nm to irradiate respectively, and the irradiation time is also longer, which exists some inconvenience in practical application. In addition, the self-healing efficiency in a short time is less than half, and it needs a day to heal, and the healing time is longer. SUMMARY

[0005] In order to solve the problems existing in the prior art, the present application provides a room temperature self-repairable silicone elastomer. The present application uses silicon rubber which is not easy to absorb water and diarylethene with stronger light stability as raw materials, introduces diarylethene photo-switching molecules containing aldehyde groups at both ends and difunctional isocyanate into the silicon rubber main chain to produce imine bonds and urea groups, and forms a silicone elastomer network.

[0006] One of the purposes of the present application is to provide a room temperature self-repairable silicone elastomer. The structure of the silicone elastomer is shown in the following formula (I)

[0007]

[0008] In formula (I), R1 is methyl or vinyl; R2 is C1-C3 alkyl; R3 is -(CH2)6、 any one of the following:

[0009] n = 12-18; m = 10-20; j = 10-20.

[0010] The second object of the present application is to provide a method for preparing the organic silicone elastomer of the first object of the present application.

[0011] The method comprises:

[0012] S1: dissolving the silicone rubber and the diaryl ethylene derivative in a first solvent, and reacting to obtain a first product;

[0013] S2: adding a difunctional isocyanate to the first product, and reacting to obtain the room-temperature self-repairable organic silicone elastomer.

[0014] Specifically, the following scheme can be used:

[0015] The silicone rubber and the diaryl ethylene derivative are dissolved in a first solvent and reacted at room temperature. After a certain period of time, thin layer chromatography is used to confirm whether the diaryl ethylene derivative has completely reacted. If the diaryl ethylene derivative has completely reacted, it is considered that the reaction is complete, and a first product is obtained. Then, a difunctional isocyanate is added to the first product and reacted at room temperature. After the reaction is complete, the solvent is volatilized and dried to obtain a yellow organic silicone elastomer.

[0016] In a preferred embodiment of the present application, the silicone rubber is an aminopropyl-terminated polydimethylsiloxane or an aminopropyl-terminated methyl vinyl silicone rubber. The diaryl ethylene derivative is any one of 4,4'-(perfluorocyclopent-1-en-1,2-diyl)bis(5-methylthiophene-2-carboxaldehyde), 4,4'-(perfluorocyclopent-1-en-1,2-diyl)bis(5-ethylthiophene-2-carboxaldehyde), and 4,4'-(perfluorocyclopent-1-en-1,2-diyl)bis(5-propylthiophene-2-carboxaldehyde). The difunctional isocyanate is any one of isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, m-xylylene diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate. The first solvent is any one of dichloromethane, tetrahydrofuran, and trichloromethane. The skilled person can select appropriate silicone rubber, diaryl ethylene derivative, difunctional isocyanate, and first solvent according to actual conditions.

[0017] In a more preferred embodiment of the present application, the aminopropyl-terminated polydimethylsiloxane has the following structure shown in formula (II)

[0018]

[0019] In formula (II), n = 16-18; or

[0020] The structure of the aminopropyl-terminated methyl vinyl silicone rubber is shown in formula (Ⅲ).

[0021]

[0022] In equation (Ⅲ), n = 12 to 15.

[0023] The reaction equation for preparing organosilicon elastomers is as follows:

[0024]

[0025] The organosilicon elastomer is an open-ring elastomer, which forms a closed-ring elastomer under ultraviolet light irradiation; the closed-ring elastomer reverts to its initial open-ring elastomer under visible light irradiation. Its photoisomerization reaction is as follows:

[0026]

[0027] In a preferred embodiment of the present invention, the molar ratio of the silicone rubber, the diarylethylene derivative, and the difunctional isocyanate is 1:0.3-0.5:0.5-0.7. Those skilled in the art can select a suitable molar ratio of the silicone rubber, the diarylethylene derivative, and the difunctional isocyanate according to actual needs. Further, in step S1, the reaction time is 4-6 hours; in step S2, the reaction time is 0.5-1 hour. Those skilled in the art can select a suitable reaction time according to actual needs.

[0028] The third objective of this invention is to provide a self-healing metal-coordinated organosilicon elastomer at room temperature, which is prepared by the following method:

[0029] The organometallic complex is dissolved in a second solvent, and the organosilicon elastomer described in one objective of this invention or the organosilicon elastomer obtained by the method of another objective of this invention is added. The reaction is carried out to obtain a metal-coordinated organosilicon elastomer that can self-heal at room temperature.

[0030] The following solutions can be adopted:

[0031] The organometallic complex is dissolved in a second solvent, and the organosilicon elastomer described in one objective of this invention or the organosilicon elastomer obtained by the method of another objective of this invention is added. The reaction is carried out at room temperature. After the reaction is complete, the solvent is evaporated and dried to obtain a yellow metal-coordinated organosilicon elastomer.

[0032] In a preferred embodiment of the present application, the organic metal complex is any one of tetrakis(acetonitrile) palladium tetrafluoroborate, zinc acetate, zinc diethyl dithiocarbamate. The second solvent is any one of acetonitrile, chloroform, ethyl acetate. The skilled person can select a suitable organic metal complex and second solvent according to actual needs. Further, the amount of the organic metal complex is related to the silicone rubber used in the preparation of the organic silicone elastomer, specifically, the molar ratio of the silicone rubber and the organic metal complex is 1:0.08-0.24. The skilled person can select a suitable amount of organic metal complex according to actual needs.

[0033] Taking the organic metal complex as tetrakis(acetonitrile) palladium tetrafluoroborate and the silicone rubber as aminopropyl-terminated polydimethylsiloxane as an example, the metal coordination part formed by the room-temperature self-repairable organic silicone elastomer and the organic metal complex is as follows

[0034]

[0035] In another preferred embodiment of the present application, the reaction time is 0.5-1 h. The skilled person can select a suitable reaction time according to actual needs.

[0036] Compared with the prior art, the present application has the following advantages:

[0037] The organic silicone elastomer prepared by the present application has excellent light response performance and light healing performance, can realize self-healing at room temperature, and can be repeatedly processed. On the one hand, it can be used with only one light source in the self-healing process, which is convenient for practical application. On the other hand, it can realize self-healing in a short time, and the efficiency of self-healing is significantly improved. In addition, the metal coordination organic silicone elastomer prepared by the present application also has excellent mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 ATR-IR spectrum of PDMS-DTEM-IPDI prepared in Example 1 and PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 of the present application;

[0039] Figure 2 UV absorption spectrum of PDMS-DTEM-IPDI prepared in Example 1 of the present application under 254 nm ultraviolet light irradiation;

[0040] Figure 3 UV absorption spectrum of PDMS-DTEM-IPDI prepared in Example 1 of the present application under 580 nm yellow light irradiation;

[0041] Figure 4UV absorption spectrum of PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 of the present application under 254 nm ultraviolet light irradiation;

[0042] Figure 5 UV absorption spectrum of PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 of the present application under 580 nm yellow light irradiation;

[0043] Figure 6 Stress-strain curve of two kinds of PDMS-DTEM-IPDI of Example 1 of the present application;

[0044] Figure 7 Stress-strain curve of four kinds of PDMS-DTEM-IPDI@Pd-16% of Example 2 of the present application;

[0045] Figure 8 Micrograph of PDMS-DTEM-IPDI@Pd-16% of Example 2 of the present application before ring-opening healing;

[0046] Figure 9 Micrograph of PDMS-DTEM-IPDI@Pd-16% of Example 2 of the present application after ring-opening healing;

[0047] Figure 10 Micrograph of PDMS-DTEM-IPDI@Pd-16% of Example 2 of the present application before ring-closing healing;

[0048] Figure 11 Micrograph of PDMS-DTEM-IPDI@Pd-16% of Example 2 of the present application after ring-closing healing;

[0049] Figure 12 ATR-IR spectrum of PDMS-IPDI prepared in Comparative Example 1 of the present application;

[0050] Figure 13 UV absorption spectrum of PDMS-IPDI prepared in Comparative Example 1 of the present application;

[0051] Figure 14 UV absorption spectrum of PDMS-IPDI prepared in Comparative Example 1 of the present application under 254 nm ultraviolet light irradiation;

[0052] Figure 15 Schematic diagram of PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 of the present application applied to information writing and erasing;

[0053] Figure 16Application diagram of PDMS-DTEM-IPDI@Pd-16% prepared for the embodiment 2 of the present application as the ultraviolet protection layer;

[0054] Figure 17 Application diagram of PDMS-DTEM-IPDI@Pd-16% prepared for the embodiment 2 of the present application as the ultraviolet protection layer;

[0055] Figure 18 Application diagram of PDMS-DTEM-IPDI@Pd-16% prepared for the embodiment 2 of the present application as the ultraviolet protection layer. DETAILED DESCRIPTION

[0056] The following specific description of the present application is combined with specific drawings and embodiments, and it is necessary to point out here that the following embodiments are only used for further illustration of the present application, and cannot be understood as the limitation of the protection scope of the present application. Some non-essential improvements and adjustments of the present application made by the person skilled in the art according to the content of the present application still belong to the protection scope of the present application.

[0057] In the present application, PDMS is an aminopropyl-terminated polydimethylsiloxane; DTEM is 4,4'-(perfluorocyclopent-1-en-1,2-diyl)bis(5-methylthiophene-2-carboxaldehyde); and IPDI is isophorone diisocyanate.

[0058] Embodiment 1

[0059] 4g of PDMS and 0.234g of DTEM were weighed, and the PDMS and DTEM were dissolved in dichloromethane. After stirring at room temperature for 4h, it was confirmed by thin layer chromatography that the DTEM was completely reacted. Then 0.117g of difunctional isocyanate IPDI was weighed and added to the system, and the stirring was continued at room temperature for 1h to obtain PDMS-DTEM-IPDI.

[0060] The PDMS-DTEM-IPDI prepared in embodiment 1 was subjected to ATR-IR determination, and the results are shown in Figure 1 Before testing, the reaction raw material polydimethylsiloxane (PDMS) was characterized by ATR-IR, and it was found that the characteristic peak of Si-O-Si appeared near 1000-1100cm -1 , the vibration absorption peak of the silicon methyl on PDMS appeared near 2963cm -1 , the N-H bending vibration peak of -NH2 appeared near 1600cm -1 , the reaction raw material bisaldehyde-containing dithiophene ethylene (DTEM) was characterized, and it was found that the C=O stretching vibration peak appeared near 1672cm -1 , corresponding to the C=O stretching vibration peak of the aldehyde group in the DTEM molecule, and the vibration absorption peak of the silicon methyl on PDMS appeared near 2849cm -1The stretching vibration of the aldehyde matrix atoms appeared nearby. This is the Fermi resonance peak of the aldehyde group, which is a characteristic peak of the aldehyde group.

[0061] Figure 1 The ATR-IR spectrum of PDMS-DTEM-IPDI is shown, by Figure 1 It can be seen that 2849cm on DTEM -1 Fermi resonance peak of nearby aldehyde group and 1600 cm⁻¹ on PDMS -1 The characteristic peaks of nearby amino groups disappeared, while PDMS-DTEM-IPDI peaks at 1634 cm⁻¹... -1 A new peak appeared nearby, corresponding to the characteristic peak of the imine bond (-N=CH-), indicating that a Schiff base reaction occurred during the polymerization process. The aldehyde group on the DTEM molecule was consumed, and a new imine bond was formed, successfully introducing the imine bond into the PDMS system. (1724 cm⁻¹) -1 There is a very weak absorption peak nearby, corresponding to the amide I band in the urea group (i.e., the stretching vibration of C=O), at 1571 cm⁻¹. -1 The nearby new peak corresponds to the amide I I band in the urea group (i.e., the bending vibration of NH), 1298 cm⁻¹ -1 The new peak appearing nearby corresponds to the amide III band in the urea group (i.e., the stretching vibration of CN), while the isocyanate-NCO band at 2200 cm⁻¹... -1 The absence of nearby stretching bands confirms that the added IPDI also fully participated in the reaction to form urea groups. These results confirm the successful synthesis of PDMS-DTEM-IPDI, whose structure is shown below.

[0062]

[0063] Example 2

[0064] 4 g of PDMS and 0.234 g of DTEM were weighed and dissolved in dichloromethane. After stirring at room temperature for 4 h, the complete reaction of DTEM was confirmed by thin-layer chromatography. Then, 0.117 g of difunctional isocyanate IPDI was weighed and added to the system. The mixture was stirred at room temperature for another 1 h to obtain PDMS-DTEM-IPDI. 0.22 g of Pd(CH3CN)4(BF4)2 was weighed and dissolved in 5 ml of acetonitrile by sonication to obtain a Pd salt solution. 1705 μL of the Pd salt solution was added to PDMS-DTEM-IPDI, with a molar ratio of Pd(CH3CN)4(BF4)2 to PDMS of 16%. The mixture was stirred at room temperature for another 0.5 h. After evaporation and drying of the solvent, a yellow elastomer, PDMS-DTEM-IPDI@Pd-16%, was obtained.

[0065] The PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 was subjected to ATR-IR determination, and the results are as follows:Figure 1 As shown. By Figure 1 It can be seen that PDMS-DTEM-IPDI is at 1634cm. -1 The characteristic peak of the imine bond in the vicinity, after the addition of Pd salt solution, is at 1670 cm⁻¹. -1 A new peak appeared nearby, which is attributed to the formation of a coordinate bond after the imine bond coordinates with Pd, causing a blue shift in the characteristic peak of the imine bond, confirming the coordination effect between Pd and the imine bond. Simultaneously, the urea group in PDMS-DTEM-IPDI also participated in the coordination; the amide I, amide II, and amide III bands all showed significant shifts before and after coordination. After coordination, the amide I band shifted from 1724 cm⁻¹. -1 The nearby blue color shifted to 1728cm. -1 Nearby, the amide II band extends from 1571 cm. -1 The nearby redshifted to 1547cm -1 Nearby, the amide III band extends from 1298 cm. -1 The nearby blue color shifted to 1330cm. -1 This confirms that there is coordination between Pd and both the N and O atoms on the urea group. These results demonstrate that PDMS-DTEM-IPDI can form effective coordination bonds with metallic Pd salts.

[0066] The UV-Vis absorption spectra of the PDMS-DTEM-IPDI prepared in Example 1 were measured. The method involved spin-coating the PDMS-DTEM-IPDI onto a glass slide and then performing UV absorption spectroscopy. The results are as follows: Figure 2 and Figure 3 As shown. Figure 2 In the process, the elastomer PDMS-DTEM-IPDI produced two new peaks in the visible light region, located at 348-421nm and 446-717nm respectively. At the same time, the absorption peak at 266nm in the ultraviolet region decreased significantly, and two isoabsorption points appeared, located at 238nm and 309nm respectively. After 30 minutes of illumination, the elastomer basically reached the photosteady state. Figure 3 In the experiment, the two new peaks of the elastomer PDMS-DTEM-IPDI in the visible light region decreased significantly until they disappeared, while the absorption peak at 266 nm in the ultraviolet region reappeared, and two isoabsorption points appeared, located at 241 nm and 308 nm, respectively. After 4 minutes of illumination, the elastomer basically reached a photosteady state. This confirms that the PDMS-DTEM-IPDI prepared in Example 1 has obvious photoreversibility.

[0067] The UV-Vis absorption spectra of PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 were measured using the same method, and the results are as follows: Figure 4 and Figure 5 As shown. Figure 4In the visible region, the elastomer PDMS-DTEM-IPDI@Pd-16% produced two new peaks at 354-446 nm and 455-748 nm, and the absorption peak at 265 nm in the ultraviolet region decreased significantly, and two isosbestic points appeared at 240 nm and 310 nm. After 30 min of irradiation, the elastomer basically reached a photostationary state. Figure 5 In the visible region, the two new peaks of the elastomer PDMS-DTEM-IPDI@Pd-16% decreased significantly until disappeared, and the absorption peak at 266 nm in the ultraviolet region recovered again, and two isosbestic points appeared at 240 nm and 308 nm. After 4 min of irradiation, the elastomer basically reached a photostationary state. It was confirmed that the PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 had obvious photo-reversibility.

[0068] The self-healing performance test was performed on the PDMS-DTEM-IPDI prepared in Example 1. The mechanical properties of the elastomer were characterized by fracture toughness W, which was defined as the energy dissipated during the fracture process, calculated by integrating the area under the stress-strain curve:

[0069]

[0070] In formula (1), ε is the strain, and σ is the stress.

[0071] The ratio of the healing fracture toughness of the sample to the original fracture toughness of the sample was defined as the self-repairing efficiency η

[0072]

[0073] In formula (2), W1 is the energy dissipated during the fracture process before healing, and W2 is the energy dissipated during the fracture process after healing.

[0074] The method for self-healing performance test was as follows: a dumbbell-shaped sample (length 50 mm, narrow parallel width 4 mm) was obtained by punching and cutting the blocky elastomer with a dumbbell-shaped cutter of national standard type 3. The stress-strain curve of the PDMS-DTEM-IPDI elastomer was tested at room temperature using a Mark 10 tensile testing machine at a stretching rate of 50 mm / min. At least five samples were tested for each sample, and the stress-strain curve of the PDMS-DTEM-IPDI before self-healing was obtained. The dumbbell-shaped sample was completely cut by a blade, and the two ends of the fracture surface were in contact with each other, and was kept in a 25°C oven for 12 h without any external stimulus. It should be noted that the oven is a closed space, which is a dark space without light irradiation. After 12 h in the oven, the stress-strain curve of the elastomer was tested at room temperature using a Mark 10 at a stretching rate of 50 mm / min, and the stress-strain curve of the PDMS-DTEM-IPDI after self-healing was obtained. The results are shown in Table 1. Figure 6As shown. (Through) Figure 6 It can be seen that the stress-strain curves before and after self-healing show almost no significant change. The tensile strength and elongation at break before and after self-healing are both within reasonable error and the values ​​are approximately the same, and the fracture toughness is 0.0034. Therefore, it can be concluded that the mechanical properties before and after self-healing do not change significantly. According to equations (1) and (2), the self-healing efficiency of PDMS-DTEM-IPDI is 100%.

[0075] The self-healing performance of PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 was tested using the same method as described above, and the results are as follows: Figures 7 to 11 As shown. Figure 7 Stress-strain curves for four types of PDMS-DTEM-IPDI@Pd-16% are shown. The fracture toughness and self-healing efficiency of PDMS-DTEM-IPDI-@Pd-16%-Open (open-loop state) and PDMS-DTEM-IPDI-@Pd-16%-Close (closed-loop state) are calculated according to Equations (1) and (2) (as shown in Table 1).

[0076] Table 1. Fracture toughness and self-healing efficiency of PDMS-DTEM-IPDI-@Pd-16%-Open (open-loop state) and PDMS-DTEM-IPDI-@Pd-16%-Close (closed-loop state).

[0077]

[0078] according to Figure 7 It can be seen that PDMS-DTEM-IPDI@Pd-16%-Open (open-loop state) can be stretched to 800% at a speed of 50 mm / min. After 12 hours of self-healing at room temperature, it can be stretched to 610%, with a healing efficiency of 62.5%. Similarly, PDMS-DTEM-IPDI@Pd-16%-Close (closed-loop state) can be stretched to 870% at a speed of 50 mm / min. After 12 hours of self-healing at room temperature, it can be stretched to 870%, with a healing efficiency of 88.5%.

[0079] PDMS-DTEM-IPDI-@Pd-16% -Open (open ring state) self-repairing efficiency was 62.5%, and PDMS-DTEM-IPDI@Pd-16%-Close (closed ring state) self-repairing efficiency was 88.5%. This proves that the controllability of the self-repairing performance of the PDMS-DTEM-IPDI-@Pd-16% elastomer can be achieved by introducing the DTEM molecule. This can be attributed to the fact that when the DTEM is closed, the planar degree of the molecular configuration increases, which changes the distance between the imine bonds connected to the DTEM, and is more conducive to the dynamic repair between different imine bonds, thereby improving the self-repairing performance of the material. In addition, Figure 7 It is shown that the mechanical performance can be adjusted by opening and closing the DTEM.

[0080] Figure 8 and Figure 9 respectively show the microscopic photographs of PDMS-DTEM-IPDI@Pd-16%-Open before healing and after healing. According to Figure 8 and Figure 9 it can be known that the cut of the open ring state elastomer is not completely healed after 12 hours of self-healing. Figure 10 and Figure 11 respectively show the microscopic photographs of PDMS-DTEM-IPDI@Pd-16%-Close before healing and after healing. According to Figure 10 and Figure 11 it can be known that the cut almost disappears after 12 hours of natural light or light shielding, which proves that the PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 has the performance of self-healing at room temperature, and can realize self-healing in a short time, the self-healing efficiency is significantly improved, and can be applied to the scratch repair of the coating.

[0081] It can be found by comparison that the fracture toughness of PDMS-DTEM-IPDI is 0.0034, and the fracture toughness of PDMS-DTEM-IPDI-@Pd-16% is 0.6151, which means that the introduction of metal coordination bond further enhances the mechanical properties of the silicone elastomer.

[0082] Comparative Example 1

[0083] 4g of PDMS was weighed and dissolved in dichloromethane, and then 0.117g of difunctional isocyanate IPDI was added to the system, and the stirring was continued at room temperature for 1h to obtain PDMS-IPDI. The PDMS-IPDI prepared in Comparative Example 1 was subjected to ATR-IR determination, and the results are shown in Figure 12 It can be known from Figure 12 that 3335cm -1 is the absorption peak of -NH in urea group, and 2962cm -1is the stretching vibration peak of methyl-CH, 1740-1600 cm -1 is the carbonyl absorption region in urea group, 1100-1000 cm -1 is the bending vibration peak of polysiloxane skeleton Si-O-Si, while the stretching band of isocyanate group -NCO does not appear near 2200 cm -1 , which confirms that the added IPDI participates in the reaction to form urea group.

[0084] The UV-Vis absorption spectrum of the PDMS-IPDI prepared in Comparative Example 1 was determined, and the results are shown in Figs. Figure 13 and Figure 14 It can be seen from Fig. Figure 13 that the maximum absorption wavelength is 202 nm, which is obviously different from the UV absorption spectrum of the PDMS-DTEM-IPDI prepared in Example 1. It can be seen from Fig. Figure 14 that after irradiation with UV 254 nm light for 10 min, the maximum absorption wavelength is still 202 nm, which does not change compared with Figure 13 , and no new peak appears in the visible light band, which proves that it has no photochromic phenomenon.

[0085] Comparative Example 2

[0086] 4 g of PDMS and 0.234 g of DTEM were weighed, and the PDMS and DTEM were dissolved in dichloromethane. After stirring at room temperature for 4 h, however, no elastomer was formed.

[0087] Application Example 1

[0088] The PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 was applied to the writing and erasing of information. The specific operation was as follows: the PDMS-DTEM-IPDI@Pd-16% elastomer prepared in Example 2 was placed on the surface of a vessel, which was yellow in color [as shown in Fig. Figure 15 (a)]. After irradiation with UV light for 1 min, the surface of the elastomer changed from yellow to blue [as shown in Fig. Figure 15 (b)]. A transparent mask two-dimensional code was placed on the surface of the elastomer [as shown in Fig. Figure 15 (c)], and then irradiated with yellow light for 3 min. After the two-dimensional code mask was removed, the two-dimensional code information was presented on the surface of the elastomer [as shown in Fig. Figure 15 (d)]. The surface of the elastomer containing the two-dimensional code information was irradiated with yellow light again for 3 min, and the blue color was completely removed, returning to yellow [as shown in Fig. Figure 15 (e)]. This application example also reflects the photochromic performance of the silicone elastomer of the present application.

[0089] Application Example 2

[0090] The PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 was applied to a reusable ultraviolet protective layer. The procedure was as follows: the PDMS-DTEM-IPDI@Pd-16% elastomer prepared in Example 2 was dissolved in an ethanol solvent, and the concentration of the elastomer solution was 0.4 g / ml. The elastomer solution was placed on the surface of a glass sheet by spin coating [as shown in Figure 16 (a)]. Under ultraviolet lamp (365 nm) irradiation, the surface rapidly turned blue and blocked ultraviolet irradiation of the interior substrate [as shown in Figure 16 (b)]. Under yellow light (580 nm) irradiation, it returned to normal [as shown in Figure 16 (c)]. The above process can be repeated.

[0091] Application Example 3

[0092] The PDMS-DTEM-IPDI@Pd-16% prepared in Example 2 was applied to a micro trace developer. The procedure was as follows: the prepared PDMS-DTEM-IPDI@Pd-16% elastomer was dissolved in an ethanol solvent, and an elastomer solution with a concentration of 0.02 g / ml was prepared. The elastomer solution was sprayed on the surface of a polytetrafluoroethylene mold containing a scratch (as shown in Figure 17 ). After the solvent was completely volatilized, irradiation was performed using a 254 nm ultraviolet lamp, and the trace of the scratch was clearly shown (as shown in Figure 18 ).

Claims

1. A self-healing silicone elastomer at room temperature, characterized in that: The structure of the organosilicon elastomer is shown in formula (I) below. In formula (Ⅰ), R1 is methyl; R2 is a C1-C3 alkyl group; R3 is... n=12~18; m=10~20; j=10~20.

2. A method for preparing the organosilicon elastomer as described in claim 1, characterized in that... The method includes: S1: Dissolve silicone rubber and diarylethylene derivative in the first solvent, react, and obtain the first product; S2: Add a difunctional isocyanate to the first product and react to obtain a self-healing organosilicon elastomer at room temperature.

3. The method as described in claim 2, characterized in that: The silicone rubber is an aminopropyl-terminated polydimethylsiloxane; and / or The diarylethylene derivative is any one of 4,4'-(perfluorocyclopentan-1-en-1,2-diyl)bis(5-methylthiophene-2-carboxaldehyde), 4,4'-(perfluorocyclopentan-1-en-1,2-diyl)bis(5-ethylthiophene-2-carboxaldehyde), and 4,4'-(perfluorocyclopentan-1-en-1,2-diyl)bis(5-propylthiophene-2-carboxaldehyde); and / or The difunctional isocyanate is isophorone diisocyanate; and / or The first solvent is any one of dichloromethane, tetrahydrofuran, and trichloromethane.

4. The method as described in claim 3, characterized in that: The structure of the aminopropyl-terminated polydimethylsiloxane is shown in formula (II). In formula (II), n = 16 to 18.

5. The method as described in claim 2, characterized in that: The molar ratio of the silicone rubber, the diarylethylene derivative, and the difunctional isocyanate is 1:0.3-0.5:0.5-0.

7.

6. The method as described in claim 2, characterized in that: In step S1, the reaction time is 4–6 hours; and / or In step S2, the reaction time is 0.5 to 1 hour.

7. A self-healing metal-coordinated organosilicon elastomer at room temperature, characterized in that: The metal-coordinated organosilicon elastomer was prepared by the following method: The organometallic complex is dissolved in a second solvent, and the organosilicon elastomer as described in claim 1 or the organosilicon elastomer obtained by any one of claims 2 to 6 is added. The reaction is carried out to obtain a metal-coordinated organosilicon elastomer that can self-heal at room temperature.

8. The metal-coordinated organosilicon elastomer as described in claim 7, characterized in that: The organometallic complex is any one of palladium tetrafluoroborate tetratetrafluoroborate, zinc acetate, and zinc diethyldithiocarbamate.

9. The metal-coordinated organosilicon elastomer as described in claim 7, characterized in that: The second solvent is any one of acetonitrile, chloroform, and ethyl acetate.

10. The metal-coordinated organosilicon elastomer as described in claim 7, characterized in that: The reaction time is 0.5 to 1 hour.

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