An ABA block polymer

double polyester capped aniline trimer was synthesized by the reaction of double aminocapped aniline trimer and -caprolactone with stannous octoate as catalyst

via ringopening polymerization in anhydrous toluene solution.The molecular weight of the obtained polymer was ca.5.9103

calculated through 1HNMR

very close to the data collected by gel permeation chromatography (GPC:Mn=5.0103

Mw=5.8103

DMF as solvent).The structure of the polymer was characterized and verified by 1H-NMR

FT-IR

UV-Vis

cyclic voltammetry (CV) and GPC.The polymer obtained has good solubility in common organic solvents.Both thermostability and electrostability are enhanced

compared to aniline trimer.Especially

the polymers sensibility to pH value is superior to the standalone aniline trimer.The color of the polymers solution can be changed from violet to cyanic (from pH=7 to pH=5).When the pH value is adjusted from 7 to 8

the solution color is bleached greatly.However

the standalone aniline trimer responds only to acid solution

with the color from royal purple to turquoise.The enhancement of both stability and sensibility gives the polymer more opportunity to be used as sensor materials.