Narrowing the size distribution of the polymer acid improves PANI conductivity

By narrowing the size distribution of the polymer acid template, polyaniline (PANI) that is subsequently template synthesized exhibits enhanced conductivity. We used poly(2-acrylamido-2-methyl-1-propanesulfonic acid), PAAMPSA, as the polymer acid and it was synthesized by both conventional free-radical polymerization and atom transfer radical polymerization (ATRP). ATRP-derived PAAMPSA, or aPAAMPSA, has a narrower size distribution compared to conventional PAAMPSA at comparable molecular weights. In general, PANI-aPAAMPSA is two to three times as conductive as PANI-PAAMPSA. The enhanced conductivity of PANI-aPAAMPSA is strongly correlated with increases in the conjugation length and crystallinity of PANI. More surprisingly, PANI-aPAAMPSA adopts a crystal structure that is different from that of PANI-PAAMPSA, but one that is similar to that of PANI doped with a molecular acid counterpart of AAMPSA.