In addition to medical supplies, there is also a demand for cleanliness and antibacterial properties of daily necessities, especially the requirements related to life safety and health are getting higher and higher. The rapid development of the current society has caused the proliferation of various chemicals and the abuse of antibiotics, which has also led to the emergence of a variety of unprecedented germs. Certain pathogens are variants of known pathogens, but they are more capable of infecting and multiply faster. Therefore, research on new materials with antibacterial capabilities, including antibacterial silicone rubber, is imperative.
1 Types of antibacterial agents and principles of antibacterial
The currently widely used antibacterial agents mainly include the following four types.
- Metal ion antibacterial agent
The basic principle of metal ion antibacterial agents is that the surface of bacteria is negatively charged, while metal ions are positively charged. Bacteria and metal ions are attracted to each other through the warehouse force, and contact each other; then the metal ions will damage the cell membrane of the bacteria, causing the internal tissue of the bacteria to flow out, and react with the protein and DNA in the tissue fluid, thereby causing the bacteria to fail to reproduce, metabolize, and eventually die . Taking a typical Ag+ ion antibacterial agent as an example, the binding of Ag+ ion to protein and DNA in bacteria is reversible. When the bacteria are killed, Ag+ returns to the environment and continues to participate in the inactivation of bacteria.
- Photocatalytic Nano Antibacterial Agent
The antibacterial principle of the semiconductor photocatalytic antibacterial agent is: under the condition of suitable ultraviolet light irradiation, the photocatalytic antibacterial agent will generate hydroxyl radicals through the electron absorption energy transition, and the hydroxyl radicals will interact with the active functional groups in the bacterial molecules. Reaction, and then destroy the bacteria. The photocatalytic antibacterial agent can degrade the harmful substances left by the bacteria after death, and it will not be consumed by itself. Take TiO2 as an example, by modifying it, it can expand its light absorption range, and then expand its use range. After adding TiO2 to the food cling film, its preservation effect can be 2-3 times higher than the original
- Natural antibacterial agent
The antibacterial principle of chitosan is: general bacterial cell membranes are negatively charged, and chitosan with positive amino groups can attract and bind to the negatively charged parts of bacteria, thereby confining the normal physiological activities of bacteria, thereby killing Dead bacteria. In addition, low-molecular-weight chitosan can also penetrate the bacterial cell membrane, enter the bacterial body, and react with DNA, thereby inhibiting the growth of bacteria. The sterilization performance of chitosan is related to its molecular weight, environmental pH and degree of deacetylation.
- Organic synthetic antibacterial agent
Researchers have done a lot of research on quaternary ammonium salt antibacterial agents, and have successively developed four different types of quaternary ammonium salt antibacterial agents. The current research focus on the antibacterial activity of quaternary ammonium salt is basically how to increase its antibacterial activity. The main method involves grafting an unsaturated alkyl group onto the nitrogen atom of the quaternary salt, or grafting a sulfur heteroatom onto its non-hydrophilic segment. For example, cetylpyridinium ammonium halide is also very effective in killing staphylococci with strong immunity, and it can kill almost all gram vaccine bacteria.
2 Material modification
- Body modification
The advantage of bulk modification is that the preparation process is relatively simple, the antibacterial property of the material is relatively long-lasting, and the stability is good. However, the addition of antibacterial substances easily affects the mechanical properties of silicone rubber, and the compatibility of the antibacterial agent with the silicone rubber substrate and the release of the antibacterial agent in the material should be considered.
- Surface modification
The method of surface modification can also impart good antibacterial properties to silicone rubber without damaging the mechanical properties of silicone rubber. Surface modification methods to increase the antibacterial properties of silicone rubber include direct coating and spraying of antibacterial coatings on the surface of silicone rubber, chemical grafting of antibacterial substances on the surface of silicone rubber, and surface ion implantation of materials, etc. .