Preparation And Properties Of Wetting And Dispersing Additives Via Controlled Radical Polyerizations

In the coating production process,the dispersion and stability of the pigment is an indispensable part.The selection of a suitable wetting and dispersing additive can shorten the grinding time,improve the grinding efficiency,and increase the stability of the pigment dispersion system.Carbon black FW200 and pigment red PR122 are widely used in high-grade automotive coatings and ink industry due to their excellent light resistance and weather resistance,but their high specific surface area properties make them difficult to use low molecular mass wetting and dispersing additives,the hyperdispersant with better structural regularity can provide multiple anchoring sites,and the solvation chain can form an excellent steric hindrance effect,which is the first choice for dispersing the above pigments.Although the conventional free radical polymerization process is simple and has a wide range of monomers,the obtained polymer has a relatively wide molecular mass distribution and poor wettability and dispersion performance.Most of the living polymerization techniques use a narrow monomer range and strict reaction conditions,so it is difficult to industrialize.The controlled radical polymerization has both controllability and superiority of the radical polymerization,making it possible to produce a polymer with a relatively narrow molecular mass distribution in large-scale industrial production.Based on the above background,we selected specific anchoring group and solvation chain for carbon black FW200 and pigment red PR 122.A series of coating wetting and dispersing agents with different molecular structure and molecular mass were prepared by controlled radical polymerization.It mainly includes three aspects as follows:Poly(n-butyl acrylate-r-Styrene)and poly(n-butyl acrylate-r-Styrene-r-4-vinyl pyridine)with relatively narrow molecular mass distribution were synthesized by nitroxide-mediated polymerization and TEMPO alkoxyamine single molecule initiation system.In the TEMPO initiation system,the adding of acrylate monomer might cause the phenomenons of nitrogen-oxygen radical shedding,the polymer chain undergoing double-base termination and the molecular chain losing activity to an active dead chain.Poly(n-butyl acrylate-b-4-vinyl pyridine)was synthesized by SG1/AMBN bimolecular initiator system.The Polymer dispersity index of the polymer was much lower than that obtained by conventional radical polymerization,but it was still higher than the single molecule initiation system due to the presence of AMBN in the system.Poly(n-butyl acrylate-r-4-vinyl pyridine)was synthesized by SG1/AMBN bimolecular initiator system with 4-vinylpyridine as the anchoring group and n-butyl acrylate as the solvation chain,and the application of the polymer as wetting and dispersing additive for carbon black FW200 and pigment red PR122 was investigated in great detail.Although the dispersion property of the polymer was not as good as that of the commercial YF-3,it still had a certain dispersibility to the FW200.The effects of anchoring group content and relative molecular mass on dispersion performance were discussed,which indicated the direction for further design of wetting and dispersing agent.Poly(n-butyl acrylate-r-Methyl methacrylate)-b-Poly(Styrene)and Poly(n-butyl acrylate-r-Methyl methacrylate)with relatively narrow molecular mass distribution were synthesized by atom transfer radical polymerization,ethyl 2-bromopropionate was used as initiator,cuprous bromide was used as catalyst,N,N,N’,N,’N"pentamethyldiethylenetriamine was used as complexing agent.When 4-vinylpyridine was added,it may coordinate with copper.