ABSTRACT

Polyurethane anionomers include the group of linear polyurethanes or those with lower density of cross-linking which have very small numbers of acidic functional groups, e.g. COO-or HSO3-, in their chains [147, 403]. In general, the structure of a PU anionomer chain, alike that of any PU elastomer (2), is composed of blocks and it comprises both rigid urethane segments (derived from diisocyanates and diamines) and fl exible polyether or polyester segments (formulas 72-74):

where:

R1-aromatic, alicyclic or aliphatic radical derived from diisocyanate employed in the synthesis,

R2-aliphatic chain derived from polyol, e.g. oligo-oxypropylene glycol:

R3-aliphatic radical, e.g. –(CH2)6-from diamine employed to extend the isocyanate prepolymer chain, built-in into the chain through applicable urea structures.