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What is the difference in the production process between graft polymerization and plasma induced gra

Issuing time:2023-10-20 12:06

Graft polymerization and plasma-induced grafting are two technologies used to modify the surface properties of materials. In the surface modification methods of filter membranes, the same point between the two is that the polymer (also called "graft" ”) are attached to the substrate, but there are differences in the process mechanism and process details.

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Graft polymerization is a traditional membrane surface modification technology that enhances the characteristics and performance of filter membranes by introducing new functions or changing surface properties. It mainly attaches polymer chains to the substrate and produces chemical reactions. Process The process usually involves three steps:

1. Preliminary initiating, treating the membrane surface to create reaction sites or functional groups on the substrate by using chemical initiators or heat, light, or radiation.

2. In the reaction growth stage, monomer solutions containing the desired polymer chains are prepared. Monomers are selected according to the desired properties or functions to be introduced to the membrane surface. These monomer solutions are in contact with the activated membrane surface and are added to adsorb. On the active sites to form growing polymer chains, the grafting process initiates the polymerization reaction by applying heat, light, or chemical initiators, resulting in the formation of covalent bonds between the monomers and the membrane surface.

3. Termination is completed. When the polymer chain reacts with another chain, initiator or terminator molecule, the growth of the polymer chain ends. The result is a graft copolymer with side chains that have different properties from the main chain. It is the unique properties of these graft copolymers that combine the properties of the two polymers into one material, increasing the properties and functionality of the filter membrane.

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The method of plasma-induced grafting is to use plasma (a high-energy state of matter composed of ions, electrons and neutral particles, including partially ionized gas, which contains a variety of active substances, such as free radicals, ions and excited substances). molecules) to initiate grafting, the energy provided by the plasma activates the membrane surface, breaking bonds on the surface and thus forming active sites where monomers can attach and start forming polymer chains. The process steps of plasma-induced grafting are roughly as follows:

1. Plasma treatment, the filter membrane is exposed to a plasma source, such as a low-pressure or atmospheric pressure plasma system. The plasma generates active substances that interact with the membrane surface, resulting in surface activation. Plasma treatment can introduce functional groups or create defects on the membrane surface. , thus increasing its reactivity.

2. Monomer absorption and polymerization, after plasma treatment, prepare a solution containing the monomer to be grafted onto the membrane surface. The activated membrane is in contact with the monomer solution, causing the monomer to be adsorbed to the activation site through physical or chemical interactions. Once the monomer is adsorbed to the membrane surface, polymerization will occur. The reaction conditions are achieved through various methods, including thermal Initiation, photoinitiation or chemical initiator etc., ultimately using grafted polymer chains to form covalent bonds between the membrane surface.

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3. Washing and stabilization: After the grafting reaction, the membrane is usually washed to remove any unreacted monomers or by-products. This step ensures the purity of the grafted membrane. In addition, stabilization treatments, such as thermal or chemical treatments, can be used to enhance the attachment and stability of the grafted polymer chains.

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