Synthesis of borate ester-grafted carboxylated acrylonitrile butadiene rubber and its use as electron acceptor to dissolve lithium perchlorate

A novel borate ester (BE)-grafted carboxylated acrylonitrile butadiene rubber (XNBR) was synthesized. From Fourier transform infrared, 1 H NMR and elemental analyses, the borate ester was successfully grafted to XNBR, resulting in a more flexible XNBR chain as revealed by differential scanning calorimetry. The binding energies of boron, oxygen, lithium and chlorine atoms of XNBR- g -BE–LiClO 4 are quite different from those of XNBR or LiClO 4 . Meanwhile, the wavenumbers of C  O  B  O  C, CO and C  H vibrations of the benzene ring shift towards lower values and a new shoulder peak for  CN at about 2260 cm −1 emerges. By integrating fitting peak areas of  CN groups and ClO 4 − , the fractions of  CN group and ClO 4 − bidentate bonding in XNBR- g -BE–LiClO 4 are much higher than in NBR–LiClO 4 . Based on these experiments, a possible dissociation mechanism is proposed in which the boron atom of XNBR- g -BE receives electron pairs from ClO 4 − , releasing partial positive charge of Li + to bind with  CN group. © 2016 Society of Chemical Industry