A series of novel block anionomers consisting of polyisobutylene (PIB) and poly(methacrylic acid) (PMAA) segments were prepared and characterized. The specific targets were various molecular weight diblocks (PIB-b-PMAA(-)), triblocks (PMAA(-)-b-PIB-b-PMAA(-)), and three-arm star blocks [Phi(PIB-b-PMAA(-))(3)] consisting of rubbery PIB blocks with a number-average degree of polymerization of 50-1000 (number-average molecular weight = 3000-54,000 g/mol) connected to blocks of PMAA(-) anions with a number-average degree of polymerization of 5-20. The overall strategy for the synthesis of these constructs consisted of four steps: (1) synthesis by living cationic polymerization of t-chloro-monotelechelic, t-chloro-ditelechelic, and t-chloro-tritelech-elic PIBs; (2) site transformation to obtain PIBs fitted with termini capable of mediating the atom transfer radical polymerization (ATRP) of tert-butyl methacrylate (tBMA); (3) ATRP of tBMA, and (4) hydrolysis of poly(tert-butyl methacrylate) to PMAA(-). The architectures created and the synthesis steps employed are summarized. Kinetic and model experiments greatly assisted in the development of convenient synthesis methods. The microarchitectures of the various block anionomers were confirmed by spectroscopy and other techniques.