Chain-growth condensation polymerization of p-aminobenzoic acid esters 1 bearing a tri(ethylene glycol) monomethyl ether side chain on the nitrogen atom was investigated by using lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS) as a base. The methyl ester monomer la afforded polymer with low molecular weight and a broad molecular weight distribution, whereas the polymerization of the phenyl ester monomer 1b at -20 degrees C yielded polymer with controlled molecular weight (M-n = 2800-13,400) and low polydispersity (M-w/M-n = 1.10-1.15). Block copolymerization of 1b and 4-(octylamino)benzoic acid methyl ester (2) was further investigated. We found that block copolymer of poly1b and poly2 with defined molecular weight and low polydispersity was obtained when the polymerization of 1b was initiated with equimolar LiHMDS at -20 degrees C and continued at -50 degrees C, followed by addition of 2 and equimolar LiHMDS at -10 degrees C. Spherical aggregates were formed when a solution of poly1b in THF was dropped on a glass plate and dried at room temperature, although the block copolymer of poly1b and poly2 did not afford similar aggregates under the same conditions. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1357-1363, 2010