A Route to Modify Polymeric Pigment Dispersants with Polysiloxanes by Atom Transfer Radical Polymerization

A novel approach to modify polymeric pigment dispersants with polysiloxanes was developed based on the sequential atom transfer radical polymerization (ATRP) of styrene (St) and tert-butyl acrylate (tBA), using multifunctional α-bromoisobutyryl-containing poly (dimethylsiloxane) (PDMS-Brm) as the macroinitiators and CuBr/N,N,N,N,N- pentamethyldiethylenetriamine (PMDETA) as the catalyst system. The PDMS-Brm macroinitiators were obtained from the sequential hydrosilylation of commercially available methyl polysiloxanes containing SiH groups with allyl alcohol and then α-bromoisobutyryl bromide. And then, a series of well-defined comb-like graft copolymers with a PDMS backbone and several polystyrene-block-poly (tert-butyl acrylate) (PS-b-PtBA) side-chains were synthesized via ATRP. After hydrolyzing the tert-butyl groups, the comb-like copolymers may serve as multifunctional dispersing agents in the pigment printing.