Synthesis of high molecular weight polyoxyethylene with a quaternary catalyst and study of its conductive blends with poly(2-vinyl pyridine)

High molecular weight polyoxyethylene (PEO) was synthesized by using a quaternary catalyst composed of triisobutyl aluminum, phosphoric acid, water, and N,N-dimethylaniline (DMA). Optimum synthesis conditions and some properties of the product were studied. This catalyst showed high activity and the molecular weight of the polyoxyethylene obtained can approach one million. The activity of polymerization mainly depends upon the composition of catalyst. The optimum composition is as follows: i-Bu₃Al:H₃PO ₄:H₂O:DMA = 1 : 0.17 : 0.17 : 0.10-0.15 (molar ratio).The active centers of the catalyst was thus proposed. The high molecular weight PEO synthesized by this catalyst was blended with poly(2-vinyl pyridine) (PVP) and then doped with LiCIO₄ and TCNQ to obtain a conductive elastomeric material. Ionic, electronic, and mixed (ionic-elec tronic) conductivities of blends were investigated. At a Li/ EO molar ratio of 0.1 and a TCNQ/VP molar ratio of 0.5, the mixed conductivity of the blend of PEO/PVP/LiCIO₄/ TCNQ is higher than the sum of ionic conductivity of PEO/PVP/LiCIO₄ and electronic conductivity of PEO/ PVP/TCNQ, when the weight ratio of PEO to PVP is 6/4 or 5/5. It can reach 4 × 10^-6 S/cm at room temperature. Differential scanning calorimetry, thermal gravimetric analysis, and the appearance of the blend showed that both TCNQ and LiCIO₄ can complex with PEO and PVP, thus enhancing the compatibility between PEO and PVP.