Hello everyone, I’m currently working on synthesizing polymers using methacrylated kraft lignin and methyl methacrylate (MMA) through free radical polymerization. My chosen initiator is azobisisobutyronitrile (AIBN). However, I’m facing difficulties with the initial conditions, as I haven’t been able to obtain the desired polymer. Could anyone advise me on the appropriate initial conditions to start with? I’m using dimethyl sulfoxide (DMSO) as a solvent, and the reaction is conducted at 60°C. Additionally, I’m curious if changing the solvent would impact the reaction.Thank you
Dear Ismail Khan, please have a look at the following RG link, may be it gives a partial answer. What is the nonachieved expected result by your recipe. My Regards
https://www.researchgate.net/publication/230494097_Role_of_dimethyl_sulfoxide_as_a_solvent_for_vinyl_polymerization#:~:text=They claimed that DMSO reduces,the polymer structure took place.
Dear Ismail Khan ! You have decided to carry out a radical copolymerization of methacrylated lignin with methyl methacrylate with DAC in dimethyl sulfoxide. That's right, and the result in the form of a composite will certainly work. The transfer rate of the chain to the solvent is small. Will you achieve your goal? It depends on the goal. What is the purpose of the experiment?
I worked with lignin and I met inhibition of radical polymerization due to phenolic hydroxyl groups acts as inhibitor o
Abdelkader BOUAZIZ Oleg Novikov Thank you for your response I am hoping to get Thermoplastics out of the product. But due homopolymer formation I have two polymers and the there are two metling points in the DSC Analysis,,,could you guide me if my approach is correct for getting thermoplastic polymer. Thanks
Dear Ismail Khan ! The methacrylic groups of lignin are immobilized, associated with massive lignin groupings. Therefore, it is difficult to expect to obtain a statistical copolymer with a high yield. This means that a homopolymer of methyl methacrylate is obtained and a polymer grafted to lignin with a small yield. Two melting points. To understand what the result of the reaction is, it is necessary to consider the rheological properties of this composite. Try to melt it. If massive lignin groups prevail, then there will be no melting. If the board is good, then the lignin is qualitatively modified.
prof. Oleg Novikov you were right. i used compression molding and did not work the sample was compressed not melted. and now in DSC Analysis of kraft lignin (my initial materials') i can see two melting point which means that kraft lignin is mixture of two polymers or compound. my question is how do i modify kraft lignin in order to get one melting point and then go for the remaining processes.Please see the DSC attached
Dear Ismail Khan ! According to the newly obtained data, the polymer has two melting points, but does not actually melt. I believe that you have modified lignin well enough, and you have obtained not even a graftpolymer, but a crosslinked polymer. Molecular chains of methyl methacrylate cross-linked lignin macromolecules into a mesh structure. Try to perform a sol-gel analysis. You will get a gel containing lignin fragments, kraft fragments and a soluble product consisting of a homopolymer of methyl methacrylate and a kraft copolymer of lignin. With fractional precipitation, there will be a separation into a pure kraft copolymer and a homopolymer. The task will be solved scientifically. Technologically, the proportion of crosslinked polymer can be reduced by fine-tuning the length of the macromolecular chain. Then the proportion of the soluble fraction can be increased to 100 percent. At the same time, the injection molding properties of the composition will also improve, the strength properties will not decrease slightly.
Dear Professor Oleg Novikov This DSC plot is of the kraft lignin, which is available commercially I have not modified it or performed any reaction. I wanted to know why this is showing two peaks or melting points. and what could i do in order to get a single melting point .should i do some purification of this commercial lignin? I need to have one polymer before proceeding to the next step, which is methacrylation. Thank you
Regardless of the actual melting temperatures, you can use my analysis of chemical mechanisms to guide the synthesis of modified lignin and the analysis of its properties. To obtain greater homogeneity, a more homogeneous product is needed. Try to purify the original lignin. To extract a narrow fraction from a commercial product, in particular low molecular weight and low melting. But in the future, you will still have to look for ways to obtain the most grafted copolymer, which is a difficult task of synthesis.
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