Post-polymerization functionalization method This method is to form the main chain and then introduce the side chain, generally using the existing known molecular weight of polycarboxylate superplasticizer, under the action of a catalyst and polyether esterification reaction at a higher temperature.
The problem of this method is that the compatibility between polycarboxylic acid and polyether is not good, and the phase separation occurs in the process of esterification, which makes the esterification operation difficult.
Therefore, the selection of polyether with good compatibility with polycarboxylic acid is the key to synthesis work.
In situ polymerization and graft In this method, side chains are introduced at the same time as the main chain polymerization.
As a reaction medium of carboxylic acid unsaturated monomers, polyether overcomes the problem of poor compatibility between polyether and carboxylic acid.
The method is to add the mixture of acrylonic acid monomer, chain transfer agent and initiator to the aqueous solution containing methoxy polyethylene glycol step by step and react under certain conditions.
Although this method can control the molecular weight of the polymer, the main chain can only select the monomer containing a C00H group, otherwise it is difficult to graft, and this graft reaction is a reversible equilibrium reaction, there is a lot of water in the system before the reaction, the degree of grafting is not very high and difficult to control.
This method is simple in process and low in production cost, but difficult in molecular design.
