Quaternary phosphonium POSS (polyhedral oligomeric silsesquioxane) modified antibacterial flame-retardant silicone rubber and preparation method thereof

Abstract

The invention discloses quaternary phosphonium POSS (Polyhedral Oligomeric Silsesquioxane) modified antibacterial flame-retardant silicone rubber and a preparation method thereof. The preparation method comprises the following steps: 1) reacting 1 part of octa-tert-phosphino POSS with 3-6 parts of a halogenated compound in an organic solvent at 60-120 DEG C for 24-48 hours, then adding 2-5 parts of an epoxy coupling agent, and continuously reacting for 24 hours to obtain modified octa-tert-phosphino POSS; and 2) curing 1-9 parts of the modified octa-tert-phosphino POSS, 100-120 parts of polysiloxane, 10-14 parts of a siloxane cross-linking agent and 0.5-4 parts of a catalyst at room temperature for 12-24 hours to obtain the antibacterial flame-retardant silicone rubber. According to the antibacterial flame-retardant silicone rubber disclosed by the invention, the tensile strength, the tear resistance and the interface stability are greatly improved, the bottleneck that antibacterial, flame-retardant and mechanical properties of silicone rubber are difficult to consider is successfully broken through, and the application prospect is wide.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone rubber and antibacterial technology, and particularly relates to a quaternary phosphonium modified POSS modified antibacterial flame-retardant silicone rubber and a preparation method thereof. BACKGROUND

[0002] As a kind of high molecular elastic body with a main chain composed of silicon-oxygen bonds (Si-O-Si) and side chains connected with organic groups, silicone rubber has a unique molecular structure, combining the thermal stability of inorganic materials and the flexibility of organic materials, and occupies a key position in modern industry and cutting-edge technology. In the field of biomedicine, its excellent biocompatibility makes it an ideal material for long-term implantable medical devices (such as cardiac pacemaker lead insulation layer and artificial joint seal), which can effectively avoid immune rejection and ensure long-term stable operation of the device; in the field of high-end electronic packaging and cables, silicone rubber has excellent electrical insulation, low dielectric constant, and excellent corona and arc resistance, which can provide reliable protection for precision electronic components and resist electrical breakdown risk; in extreme environment application scenarios such as aerospace engine seals and deep-sea exploration equipment protection, silicone rubber exhibits high and low temperature resistance, ozone resistance and weather resistance, ensuring the long-term service of the equipment under harsh conditions.

[0003] However, the inherent defects of silicone rubber seriously restrict its application expansion. From the perspective of antibacterial performance, the surface of silicone rubber is chemically inert and has low surface energy, making it an ideal place for microorganisms (such as E. coli and Staphylococcus aureus) to adhere and colonize. Bacteria form biofilms on its surface, not only causing material appearance degradation and mechanical property decline, but also causing serious nosocomial infection problems in medical scenarios. According to statistics, about 30%-50% of medical device-related infections are closely related to biofilm formation. From the perspective of flame retardant safety, the limiting oxygen index (LOI) of silicone rubber is relatively low (about 18-22%), which belongs to flammable materials. Although it has low smoke density, it releases heat when burning, which poses a fire hazard in electronic and electrical, transportation (such as high-speed rail / aircraft cable insulation), building, etc. fields, and its flame retardant performance needs to be improved to meet strict fire safety standards. From the perspective of mechanical properties, the tensile strength of unmodified silicone rubber usually hovers around 0.5-1.5 MPa, and the elongation at break is mostly in the range of 100%-200%, which is difficult to meet the requirements of complex working conditions with high load and high dynamic stress. When subjected to a large external force, it is prone to tearing, breaking and other failure phenomena.

[0004] To endow silicone rubber with antibacterial properties, previous studies mainly focused on the addition of antibacterial agents. Quaternary ammonium salt antibacterial agents have been widely used because the cationic groups in their structure can be electrostatically adsorbed to the anionic sites on the surface of bacterial cell membranes, thereby destroying the integrity of the cell membranes. However, bacteria can easily develop resistance to quaternary ammonium salts over a long period of use, and quaternary ammonium salts degrade slowly in the environment, posing a potential ecological risk. In comparison, quaternary phosphonium salt antibacterial agents have gradually become a research hotspot because the cationic groups formed by the phosphorus atoms have stronger interactions with bacterial cell membranes than the cationic groups formed by nitrogen atoms, and quaternary phosphonium salts have a broader antibacterial spectrum and higher antibacterial efficiency, including good inhibitory effects on drug-resistant bacteria. However, the polarity difference between quaternary phosphonium salts and silicone rubber matrices is large, and simple physical blending can easily lead to phase separation, resulting in uneven dispersion and easy migration and precipitation of the antibacterial agents. This not only makes it difficult to stably exert the antibacterial activity of the antibacterial agents, but also deteriorates the mechanical properties of silicone rubber due to the introduction of a second phase.

[0005] Phosphorus-containing compounds, including quaternary phosphonium salts and their derivatives, are also a class of efficient and environmentally friendly flame retardants. Their flame-retardant mechanism is mainly based on condensed phase action: during combustion, phosphorus elements can promote the dehydration of silicone rubber matrices to form carbon, and a dense, heat- and oxygen-insulating carbon layer is formed; at the same time, phosphorus-based radicals can capture hydrogen radicals and hydroxyl radicals in the gas phase to interrupt the combustion chain reaction.

[0006] In terms of improving the mechanical properties of silicone rubber, the introduction of nano-reinforcing fillers is a common strategy. Polyhedral oligomeric silsesquioxanes (POSS) are a kind of nano-scale organic-inorganic hybrid materials with a regular cage-shaped siloxane skeleton and modifiable organic functional groups. The nano-size effect of POSS can effectively limit the movement of silicone rubber molecular chains, uniformly disperse stress, and significantly improve the mechanical properties of the material, such as tensile strength and modulus. However, under conventional physical filling methods, there is only weak van der Waals force between the POSS and the silicone rubber matrix, and the interface is prone to debonding under the influence of long-term external forces or environmental factors, leading to the gradual loss of the reinforcing effect and the deterioration of the material properties.

[0007] The simultaneous optimization of the antibacterial function, flame-retardant properties, and mechanical properties of silicone rubber is a difficult problem. On the one hand, the addition of antibacterial agents / flame retardants often interferes with the construction of the crosslinked network of silicone rubber, weakens the interaction between molecular chains, and causes the mechanical properties to decline; on the other hand, excessive strengthening of the mechanical properties (such as the addition of a large amount of rigid fillers) can hinder the effective dispersion and action of functional additives (antibacterial agents, flame retardants), reducing their efficiency. Therefore, through precise molecular design and material synthesis strategies, the synergistic effect of quaternary phosphonium salt antibacterial / flame-retardant groups and POSS reinforcing units in the silicone rubber matrix needs to be achieved to construct an integrated material system that has persistent antibacterial properties, excellent flame-retardant safety, high mechanical strength, and good structural stability. In this patent, the antibacterial / flame-retardant functional units of quaternary phosphonium salt-modified POSS are covalently and stably connected to silicone rubber through the ring-opening reaction of the epoxy groups by tertiary phosphine groups. SUMMARY

[0008] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber and a preparation method thereof.

[0009] To achieve the above-mentioned objects and other related objects, the present application is obtained by the following technical solutions.

[0010] The first aspect of the present application protects a preparation method of a quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber, characterized in that it comprises the following steps:

[0011] 1) 1 part of octaphosphine POSS is reacted with 3-6 parts of a halogenated compound in an organic solvent at 60-120℃ for 24-48 hours, and then 2-5 parts of an epoxy coupling agent is added to continue the reaction for 24 hours to obtain modified octaphosphine POSS;

[0012] 2) 1-9 parts of the modified octaphosphine POSS, 100-120 parts of polysiloxane, 10-14 parts of a siloxane crosslinking agent and 0.5-4 parts of a catalyst are cured at room temperature for 12-24 hours to obtain the antibacterial and flame-retardant silicone rubber.

[0013] The present application utilizes the formation of quaternary phosphonium salt structure by the reaction of halogenated compound and octaphosphine POSS to introduce antibacterial and flame-retardant functional groups; then the ring-opening reaction of the epoxy group in the epoxy coupling agent with the remaining active tertiary phosphine group occurs to make the POSS connect with the alkoxy coupling group; finally in the curing process, the alkoxy coupling group further reacts with the silicone rubber matrix to firmly integrate the modified POSS into the crosslinked network, thereby realizing the triple synergistic effect of antibacterial, flame-retardant and mechanical enhancement.

[0014] In some embodiments, the octaphosphine POSS has the following structural formula, and the CAS number is 200200-88-0.

[0015] In some embodiments, the halogenated compound is selected from one or more of chlorododecane, chlorohexadecane, bromododecane, bromohexadecane, hexadecyl chloroacetate, benzyl chloride and benzyl bromide.

[0016] In some embodiments, the epoxy coupling agent is selected from one or more of KH-560, KH550, KH570, A-187, KH-792 and A-171.

[0017] In some embodiments, the polysiloxane is selected from one or more of 107 silicone rubber, 110 silicone rubber and 120 silicone rubber.

[0018] In some embodiments, the siloxane crosslinking agent is selected from one or more of ethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, and polyethyl silicate.

[0019] In some embodiments, the catalyst is selected from one or more of dibutyl tin dilaurate, dibutyl tin dioctoate, tetrabutyl titanate, triethylamine, and acetylacetone zirconium.

[0020] In some embodiments, the solvent is selected from one or more of toluene, xylene, ethylbenzene, chlorobenzene, dichloromethane, and acetone.

[0021] In some embodiments, the continuing the reaction further comprises removing the solvent and drying.

[0022] A second aspect of the present application protects the antibacterial and flame-retardant silicone rubber obtained by the preparation method described above.

[0023] The antibacterial and flame-retardant silicone rubber of the present application not only performs well in terms of antibacterial performance, but also has a bactericidal rate of 98.3% for E. coli and S. aureus, has excellent flame-retardant performance, can effectively slow down or stop the spread of flames, and has good mechanical properties, with an elongation at break of 269.61%.

[0024] A third aspect of the present application protects the use of the antibacterial and flame-retardant silicone rubber described above in medical devices and electronic appliances.

[0025] The antibacterial and flame-retardant silicone rubber of the present application has high-efficiency antibacterial properties, making it very suitable for use in the field of medical devices, which have very high hygiene requirements. At the same time, it has excellent flame-retardant performance, which can effectively slow down or stop the spread of flames, which is crucial for the safety of electronic appliance products. In addition, it has good mechanical properties, showing excellent flexibility and elastic properties, making the antibacterial and flame-retardant silicone rubber of the present application have great potential for use in medical devices and electronic appliances.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] The antibacterial and flame-retardant silicone rubber of the present application is prepared by chemically bonding quaternary phosphonium salt groups with both antibacterial and flame-retardant functions to the POSS cage structure, and introducing them into the polysiloxane (silicone rubber) crosslinking network through ring-opening reaction of phosphine groups and epoxy group coupling agents; quaternary phosphonium salt (phosphine group) provides long-lasting and efficient antibacterial properties, while its phosphorus element plays an intrinsic flame-retardant role; the POSS nanoskeleton also has a certain reinforcing effect on the silicone rubber; that is, the octaphosphine POSS cage structure is integrated into the silicone rubber crosslinking network, and the triple synergistic improvement is realized simultaneously: the bonded quaternary phosphonium salt provides long-lasting and efficient antibacterial properties and significantly inhibits biofilm formation, while its phosphorus element plays an intrinsic flame-retardant role, promotes char formation and captures free radicals to improve the flame-retardant safety of the material; and the POSS nanoskeleton effectively enhances the matrix, greatly improves the tensile strength, tear resistance and interface stability, successfully breaking through the bottleneck that the "antibacterial-flame-retardant-mechanical" properties of silicone rubber are difficult to be considered. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The nuclear magnetic resonance hydrogen spectrum of the octaphosphine POSS quaternary phosphonium salt modified prepared in Example 1.

[0029] Figure 2 The stress-strain curve of the surface of the antibacterial and flame-retardant silicone rubber prepared in Example 1.

[0030] Figure 3 The tensile strength and elongation at break of the antibacterial and flame-retardant silicone rubber prepared in Example 1.

[0031] Figure 4 The bactericidal graph of the antibacterial and flame-retardant silicone rubber prepared in Example 1 on Escherichia coli and Staphylococcus aureus. DETAILED DESCRIPTION

[0032] The embodiments of the present application will be described in detail below with specific reference being made to certain specific examples. The advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure herein. The present application can also be implemented or applied in other different specific embodiments, and various modifications or changes can be made to the details herein based on different views and applications without departing from the spirit of the present application.

[0033] Before further describing the specific embodiments of the present application, it should be understood that the scope of protection of the present application is not limited to the following specific embodiments; it should also be understood that the terms used in the embodiments of the present application are for the purpose of describing the specific embodiments, but not for limiting the scope of protection of the present application; in the specification and claims of the present application, the singular forms "one", "an" and "this" include the plural forms, unless otherwise explicitly stated herein.

[0034] When the embodiments give numerical ranges, it is understood that unless the embodiments expressly contradict, every numerical range's two endpoints, and any number that falls between the two endpoints, can be elected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. Except in the Examples, or where otherwise explicitly indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The materials, methods, and examples provided herein are illustrative only and, except in the Examples, or where otherwise explicitly indicated, are not intended to be limiting.

[0035] The experimental methods described in the following examples are routine methods, unless otherwise specified; the reagents and materials described are commercially available, unless otherwise specified.

[0036] Example 1

[0037] A phosphonium-modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided in this Example 1, comprising the following steps:

[0038] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) was dissolved in toluene with bromododecane (0.35 g), and reacted at 60°C for 48 hours. Then KH-560 (0.39 g) was added and the reaction was continued for 24 hours. The solvent was removed by rotary evaporation, and the product was dried to obtain phosphonium-modified octaphosphine POSS.

[0039] (2) The product (0.1 g) obtained in (1) was mixed with 107 silicone rubber (10 g), and then tetraethyl orthosilicate (1 g) and dibutyltin dilaurate (0.05 g) were added. After curing at room temperature for 12 hours, an antibacterial and flame-retardant silicone rubber was obtained, labeled as RTVSR-P1. The proportion of octaphosphine POSS in the total formulation was 1 wt%.

[0040] The molar ratio of octaphosphine POSS / bromododecane was adjusted to δ = 1:3.

[0041] Example 2

[0042] A phosphonium-modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided in this Example 2, comprising the following steps:

[0043] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) was dissolved in toluene with bromododecane (0.35 g), and reacted at 60°C for 48 hours. Then KH-560 (0.39 g) was added and the reaction was continued for 24 hours. The solvent was removed by rotary evaporation, and the product was dried to obtain phosphonium-modified octaphosphine POSS.

[0044] (2) (1) The product (0.9 g) was mixed with 110 silicone rubber (12 g), then methyltrimethoxysilane (1.4 g) and dibutyltin dioctoate (0.4 g) were added. After curing at room temperature for 24 hours, an antibacterial and flame-retardant silicone rubber was obtained, which was labeled as RTVSR-P9. The proportion of octaphosphine POSS in the total formulation was 9 wt%.

[0045] The molar ratio of octaphosphine POSS / halogenated compound was adjusted to δ = 1:6.

[0046] Example 3

[0047] In this example 3, a quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided, which comprises the following steps:

[0048] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) was dissolved in ethylbenzene with chlorododecane (0.42 g), and reacted at 70°C for 44 hours. Then KH-570 (0.62 g) was added and the reaction was continued for 24 hours. After removing the solvent by rotary evaporation and drying, the quaternary phosphonium modified octaphosphine POSS was obtained.

[0049] (2) (1) The product (0.2 g) was mixed with 120 silicone rubber (10.5 g), then methyltriethoxysilane (1.1 g) and tetrabutyl titanate (0.1 g) were added. After curing at room temperature for 14 hours, an antibacterial and flame-retardant silicone rubber was obtained, which was labeled as RTVSR-P3. The proportion of octaphosphine POSS in the total formulation was 3 wt%.

[0050] The molar ratio of octaphosphine POSS / halogenated compound was adjusted to δ = 1:4.

[0051] Example 4

[0052] In this example 3, a quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided, which comprises the following steps:

[0053] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) was dissolved in chlorobenzene with chlorohexadecane (0.65 g), and reacted at 80°C for 40 hours. Then A-187 (0.8 g) was added and the reaction was continued for 24 hours. After removing the solvent by rotary evaporation and drying, the quaternary phosphonium modified octaphosphine POSS was obtained.

[0054] (2) (1) The product (0.3 g) was mixed with 107 silicone rubber (11 g), then vinyltriethoxysilane (1.2 g) and tetrabutyl titanate (0.15 g) were added. After curing at room temperature for 16 hours, an antibacterial and flame-retardant silicone rubber was obtained, which was labeled as RTVSR-P5. The proportion of octaphosphine POSS in the total formulation was 5 wt%.

[0055] By adjusting the molar ratio of octaphosphine POSS / halogenated compound δ = 1:5.

[0056] Example 5

[0057] A quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided in this Example 5, comprising the following steps:

[0058] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) and hexadecyl chloroacetate (1.06 g) were dissolved in dichloromethane, and reacted at 90°C for 36 hours, then KH-792 (0.74 g) was added and the reaction was continued for 24 hours. After removing the solvent by rotary evaporation and drying, the quaternary phosphonium modified octaphosphine POSS was obtained.

[0059] (2) The product (0.4 g) obtained in (1) was mixed with 107 silicone rubber (11.5 g), then polysilicate ethyl ester (1.3 g) and triethylamine (0.2 g) were added, and after curing at room temperature for 18 hours, an antibacterial and flame-retardant silicone rubber was obtained, marked as RTVSR-P7. The proportion of octaphosphine POSS in the total formulation was 7wt%.

[0060] By adjusting the molar ratio of octaphosphine POSS / halogenated compound δ = 1:6.

[0061] Example 6

[0062] A quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided in this Example 6, comprising the following steps:

[0063] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) and benzyl chloride (0.18 g) were dissolved in acetone, and reacted at 100°C for 32 hours, then A-171 (0.25 g) was added and the reaction was continued for 24 hours. After removing the solvent by rotary evaporation and drying, the quaternary phosphonium modified octaphosphine POSS was obtained.

[0064] (2) The product (0.5 g) obtained in (1) was mixed with 107 silicone rubber (10 g), then tetraethyl orthosilicate (1 g) and acetylacetone zirconium (0.25 g) were added, and after curing at room temperature for 20 hours, an antibacterial and flame-retardant silicone rubber was obtained.

[0065] By adjusting the molar ratio of octaphosphine POSS / halogenated compound δ = 1:3.

[0066] Example 7

[0067] A quaternary phosphonium POSS modified antibacterial and flame-retardant silicone rubber and a preparation method thereof are provided in this Example 7, comprising the following steps:

[0068] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) was dissolved in ethylbenzene with benzyl bromide (0.64 g) and reacted at 110 °C for 28 hours, then KH-560 (0.59 g) was added and reacted for another 24 hours. The solvent was removed by rotary evaporation and the product was dried to obtain the quaternary phosphonium-modified octaphosphine POSS.

[0069] (2) The product (0.6 g) obtained in (1) was mixed with 107 silicone rubber (12 g), then tetraethyl orthosilicate (1.4 g) and dibutyltin dilaurate (0.3 g) were added. After curing at room temperature for 22 hours, an antibacterial and flame-retardant silicone rubber was obtained.

[0070] The molar ratio of octaphosphine POSS / halogenated compound was adjusted to δ = 1:4.

[0071] Example 8

[0072] In this example 8, an antibacterial and flame-retardant silicone rubber modified by quaternary phosphonium POSS and a preparation method thereof are provided, which comprises the following steps:

[0073] (1) Octaphosphine POSS (CAS: 200200-88-0) (1 g) was dissolved in chlorobenzene with bromododecane (0.59 g) and reacted at 120 °C for 24 hours, then KH-550 (0.74 g) was added and reacted for another 24 hours. The solvent was removed by rotary evaporation and the product was dried to obtain the quaternary phosphonium-modified octaphosphine POSS.

[0074] (2) The product (0.8 g) obtained in (1) was mixed with 107 silicone rubber (10 g), then methyltrimethoxysilane (1 g) and dibutyltin dioctoate (0.35 g) were added. After curing at room temperature for 24 hours, an antibacterial and flame-retardant silicone rubber was obtained.

[0075] The molar ratio of octaphosphine POSS / halogenated compound was adjusted to δ = 1:5.

[0076] Comparative Example 1

[0077] The difference between this comparative example 1 and example 1 is that no quaternary phosphonium-modified octaphosphine POSS was added, and the rest was the same as example 1. The obtained antibacterial modified silicone rubber was marked as RTVSR sample.

[0078] NMR hydrogen spectrum: the results are shown in Figure 1 . Among them, a is -CH2- and -CH3-, b is -OCH3, f, h, i, j, k, m represent benzene ring protons.

[0079] From Figure 1It can be seen that the hydrogen protons on -CH2- and -CH3- are at chemical shift 0-2 ppm, and the hydrogen protons on -OCH3- are at chemical shift 3.42 ppm. The hydrogen protons on the benzene ring are at chemical shift 7.15-7.42 ppm, which proves that the octaphosphine group is successfully quaternized.

[0080] Stress-strain curve: The tensile properties of the antibacterial and flame-retardant silicone rubber obtained in Examples 1-5 and Comparative Example 1 were tested by using a high and low temperature double column tester produced by Instron Company, model number Instron5996. According to the standard GB / T528-1998 “Test method for tensile stress-strain properties of vulcanized or thermoplastic rubber”, dumbbell type I samples were selected for the tensile test, and the test rate was set to 20 mm / min. The average value of three data sets obtained for all samples was calculated. The stress-strain curve is shown in Figure 2 .

[0081] From Figure 2 it can be seen that the blank control group (RTVSR) without the addition of quaternized modified octaphosphine POSS has a low peak value, a short elongation at break, and poor mechanical properties; as the addition amount increases from 1 wt% to 5 wt% (RTVSR-P1 to RTVSR-P5), the peak stress of the curve gradually increases, the strain at break significantly increases, and the strength and toughness of the antibacterial and flame-retardant silicone rubber are simultaneously improved, among which RTVSR-P5 has the highest peak value (1.13 MPa) and the largest elongation at break (269.61%); when the addition amount exceeds 5 wt% (RTVSR-P7 to RTVSR-P9), the peak stress of the curve decreases, the elongation at break shortens, and the mechanical properties begin to deteriorate.

[0082] Tensile strength and elongation at break: The tensile properties of the antibacterial and flame-retardant silicone rubber of Examples 1-5 and Comparative Example 1 were tested by using a high and low temperature double column tester produced by Instron Company, model number Instron5996. According to the standard GB / T528-1998 “Test method for tensile stress-strain properties of vulcanized or thermoplastic rubber”, dumbbell type I samples were selected for the tensile test, and the test rate was set to 20 mm / min. The average value of three data sets obtained for all samples was calculated. The results are shown in Figure 3 .

[0083] From Figure 3 it can be seen that the mechanical properties of Comparative Example 1 (RTVSR sample) are not good, with an elongation at break of 134.99% and a tensile strength of 0.54 MPa.

[0084] With the addition of modified octylphosphine-based POSS, the mechanical properties of the antibacterial and flame-retardant silicone rubber were significantly improved, among which the elongation at break (269.61%) and tensile strength (1.13 MPa) of the RTVSR-P5 sample were the highest. By comparing the samples with different addition amounts (RTVSR-P1 to RTVSR-P9), it can be seen that the elongation at break and tensile strength first increased and then decreased with the increase of the addition amount, and when the addition amount exceeded 5 wt%, both indicators began to decrease.

[0085] Antibacterial performance research: Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were selected as the antibacterial experimental objects. Bacterial culture process: take the strain and coat it on the surface of the solid culture medium, seal it with a sealing film, invert it, and place it in a 37°C constant temperature incubator for 12 h. Then, select independent colonies at the tail end of the colony and inoculate them into Luria-Bertani (LB) liquid medium, and then place them in a 37°C constant temperature incubator for 12 h at a speed of 180 rpm. Before the antibacterial experiment, the concentrated bacterial solution cultured as above was diluted with clean LB liquid medium to the required concentration (ODS=~0.05, ODE=~0.1 at 600 nm wavelength).

[0086] Plate colony counting test: the antibacterial and flame-retardant silicone rubber of examples 1-5 and comparative example 1 was cut into a size of 30 mm x 30 mm, and placed in anhydrous ethanol for dialysis for 1 day. After drying, it was placed in a plastic surface dish, and the bacteria attached to it were killed by irradiation with a UV lamp for 1 h. A 20 mm x 20 mm size of PE material preservative film was cut and prepared. Take 5 mL of bacteria solution diluted to a certain concentration, and inject it into the first hole of a 12-hole plate. Then take 0.5 mL of LB liquid medium from the first hole, and add 4.5 mL of LB liquid medium to it, so that the concentration of the medium in the hole is reduced to 1 / 10 of the previous hole. Repeat the operation until the concentration of the bacteria solution is diluted to 10-6 times the initial concentration. Take 100 μL of the 10-6 dilution of the bacteria solution and drop it on the surface of the antibacterial and flame-retardant silicone rubber, slowly cover the preservative film on the liquid drop on the surface of the antibacterial and flame-retardant silicone rubber, and push the liquid flat to make the bacteria solution spread evenly. Then put the sample into a constant temperature and humidity incubator set at 37°C and incubate for 24 h. Take 5 mL of 0.85 wt% NaCl solution and slowly rinse the bacteria on the surface of the antibacterial and flame-retardant silicone rubber and the preservative film, and try to rinse completely to obtain a NaCl mixed solution containing bacteria. Take 100 μL of the above mixed solution and drop it onto the surface of the solid culture medium, then evenly spread it with a coating rod, and place it in a 37°C constant temperature and humidity incubator for 24 h. Observe the growth of the colonies on the solid culture medium and take pictures. The test was repeated three times.

[0087] The number of surviving bacteria in Comparative Example 1 was denoted as N0, and the number of surviving bacteria in the experimental group was denoted as NR. The antibacterial performance R was calculated according to the following formula: R = (N0 - NR) / N0 × 100%. Results are shown below. Figure 4 .

[0088] from Figure 4 As shown in Figure A, when the addition amount increased from 1wt% to 5wt%, the sterilization rate of E. coli increased from 65.2% to 95.1%, an increase of 45.9%; when it increased from 5wt% to 9wt%, the sterilization rate of E. coli increased from 95.1% to 97.7%.

[0089] from Figure 4 As shown in Figure B, when the addition amount increased from 1wt% to 5wt%, the sterilization rate of Staphylococcus aureus increased from 70.5% to 96.2%, an increase of 36.5%; while when the addition amount increased from 5wt% to 9wt%, the sterilization rate of Staphylococcus aureus increased from 96.2% to 98.3%.

[0090] In summary, the antibacterial effect is not ideal when the dosage is too low. When the dosage reaches 5 wt%, the antibacterial effect is good, but as the dosage continues to increase, the improvement in antibacterial performance begins to decline.

[0091] The above embodiments are for illustrating the implementation schemes disclosed in this invention and should not be construed as limiting the invention. Furthermore, various modifications listed herein, as well as variations in the methods and antibacterial flame-retardant silicone rubber, will be apparent to those skilled in the art without departing from the scope and spirit of this invention. Although the invention has been specifically described in conjunction with various specific preferred embodiments, it should be understood that the invention should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the invention should be included within the scope of this invention.

Claims

1. A method for preparing a quaternary phosphonium-POSS modified antibacterial flame retardant silicone rubber, characterized in that, The method comprises the following steps: 1) 1 part of octaphosphine-POSS is reacted with 3-6 parts of halogenated compound in an organic solvent at 60-120℃ for 24-48 hours, then 2-5 parts of epoxy coupling agent is added to continue the reaction for 24 hours to obtain modified octaphosphine-POSS; 2) 1-9 parts of the modified octaphosphine-POSS, 100-120 parts of polysiloxane, 10-14 parts of siloxane crosslinking agent and 0.5-4 parts of catalyst are cured at room temperature for 12-24 hours to obtain the antibacterial and flame-retardant silicone rubber.

2. The preparation method according to claim 1, characterized in that, The halogenated compound is selected from one or more of chloro-dodecane, chloro-hexadecane, bromo-dodecane, bromo-hexadecane, hexadecyl chloroacetate, benzyl chloride and benzyl bromide.

3. The preparation method according to claim 1, characterized in that, The epoxy coupling agent is selected from one or more of KH-560, KH550, KH570, A-187, KH-792 and A-171.

4. The preparation method according to claim 1, characterized in that, The polysiloxane is selected from one or more of 107 silicone rubber, 110 silicone rubber and 120 silicone rubber.

5. The method of claim 1, wherein the compound is ###00001### 5 The siloxane crosslinking agent is selected from one or more of tetraethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane and polyethyl silicate.

6. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The catalyst is selected from one or more of dibutyltin dilaurate, dibutyltin dioctoate, tetrabutyl titanate, triethylamine and acetylacetone zirconium.

7. The preparation method according to claim 1, characterized in that, The solvent is selected from one or more of toluene, xylene, ethylbenzene, chlorobenzene, dichloromethane and acetone.

8. The antibacterial and flame-retardant silicone rubber prepared by the method of any one of claims 1-6.

9. The antibacterial and flame-retardant silicone rubber of claim 8 for use in medical devices and electronic appliances.

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