Acrylic pigment dispersants made by group transfer polymerization

Claim 1

A composition suitable for use as a dispersant having an A segment and a B segment bonded together to form a block copolymer, the A segment consisting essentially of polymerized methacrylic monomer units and the B segment consisting essentially of polymerized monomer units selected from the group consisting of acrylic and methacrylic groups, the monomer units of said A segment, when homopolymerized, having a polarity which is higher than the polarity of the monomer units of said B segment when homopolymerized, said A segment being bonded to one or more polar groups selected from the group consisting of aromatic carboxylic acids, aliphatic carboxylic acids which have at least one functional group which increases the polarity of the reaction product of the A segment with the aliphatic carboxylic acid, ammonia and primary, secondary and tertiary aliphatic amines, primary aromatic amines, ketones which are subsequently hydrolyzed to diols, orthophosphoric acid, phosphorus pentoxide, and anhydrous hydrohalogen acid, wherein said block copolymer is made by group transfer polymerization techniques at 0° C. or higher.