Fabrication of new conductive gels by tuning the macromolecular architectures using fluorinated acrylates

New semi-inter-penetrating network (SIPN) gels based on methylmethacrylate (MMA) and fluorinated acrylates were synthesized by thermal free radical polymerization. These SIPN gels had two major parts. First part was the linear chain composed of fluorostyrene (FS) and Lithium salt of 2-acrylamido-2-methylpropane sulphonic acid (LiAMPS) which was embedded in the second part, a cross linked network of MMA and fluorinated acrylates. In the first series of gels, LiAMPS was polymerized with FS to form linear chains which were then embedded in a crosslinked network of MMA and 1,1,1,3,3,3-hexafluoroisopropylacrylate (HFIPA). Gel containing equal concentration of MMA and HFIPA showed maximum conductivity with good strength. In another series, 1,1,2,2-tetrafluoroethyl acrylate (TFEA) was used instead of HFIPA in the crosslinked network. The gels based on TFEA demonstrated better conductivity and strength. In this latter series, the gel containing an almost equal amount of MMA and TFEA in the crosslinked network showed maximum conductivity with appreciable strength. The gels prepared by using only FS with no fluorinating acrylates showed good conductivity but no strength. Ionic conductivity-temperature relationship follows Arrhenius type nature. Thermal activation process was evident in all these gel series. Thus, by selecting an appropriate combination of fluorinated acrylates it is possible to prepare gel with high conductivity and appreciable strength for potential applications in lithium ion battery.