Synthesis And Characterization Of Poly(O-Aminophenol)-G-Poly(Epsilon-Caprolactone)

Poly(o-aminophenol) (POAP) grafted by poly (epsilon-caprolactone) (PCL), with the grafted rate of 68. 7% calculated by mass gain method, has been synthesized successfully through the reaction of poly (o-aminophenol) and epsilon-caprolactone, with stannous octoate as catalyst, via ring-opening polymerization in anhydrous toluene solution. The poly (o-aminophenol) was synthesized directly by o-aminophenol with ammonium persulfate. The structure of the final grafted polymer was characterized and verified by means of nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), cyclic voltammetry (CV), gel permeation chromatography(GPC) and UV-Vis spectrophotometry (UV-Vis). The molecular weight of the grafted polymer is ca. 1. 4 X 10(4) with polydispersity of 1. 03 determined by GPC with DMF as eluent. Due to the introduced PCL segments in the grafted polymer, the thermal stability and electrochemical stability of the final polymer are superior to that of the poly(o-aminophenol) as well as its solubility is improved,thus can be dissolved in some common organic solvents, such as ethanol, toluene, THF, DMF etc. Especially, the color of the polymer' s DMF solution shows obvious changes at different pH values. The color of the polymer solution can be changed from bright light brown to light brown (from pH 7 to 2) and from bright light brown to violet (from pH 7 to 12). More importantly, the process is reversible. The sensibility to pH value gives the polymer more opportunity to be used as sensor materials.