Synthesis And Properties Of Pendant Electroactive Polymers

Conducting polymers have attracted great interest in chemistry and materialscience. Among them, polyaniline has great advantages such as excellentenvironmental stability, ease of synthesis and reversible redox states. However, PANIusually exhibits some problems. First, the ill-defined molecular structure impedes thebetter understanding of the structure-property relations. Second, the poor propertiesrestrict the practical application. Last, the single functionality limits the expansion ofapplication field.In contrast to PANI, oligoanilines have already been investigated thoroughly dueto their regular structure, excellent solubility, and easy processing. However, theirstability and mechanical properties are too bad compared with those of polymers. Oneapproach is to prepare functional copolymers with well-defined structure, excellentsolubility and processability. Recently, much effort has been made for chemicallysynthesizing polymers based on oligoanilines, such as graft, alternating, andblock-like polymers. Polymers containing oligoanilines as pendants are of interest.The large side groups could decrease the molecular mobility and enhance solubility atthe same time. As we know, oligoaniline reveals reversible redox states. Each staterepresents a particular molecular structure. In this work, we investigate the propertiesof electroactive copolymers responding to the redox reactions.First, we describe the synthesis of a new alternative monomer,2,6-difluorobenzoyl aniline tetramer (DFAT), by using a acylation reaction. Then afacile synthesis of poly(arylene ether sulfone) copolymers with oligoaniline aspendants is presented. Recently, PANI has been utilized as a conductive filler toimprove the dielectric constant of a polymer matrix. So we have an optimistic view of obtaining high dielectric constant polymers by introducing oligoanilines into polymerchains. In this way, we can solve phase separation and migration problems existing inPANI/polymer blends.Second, we describe here the synthesis of a novel poly(aryl ether), containingpendant oligoaniline and anthracene moieties (PAE-p-OA), both side chains present inequal amounts. This material exhibits an interesting fluorescent response to redoxactive species. The copolymer can be applied as an efficient fluorescent sensor. Thisapproach to redox active species detection has several advantages. The sensoryscheme based on the redox reaction, instead of the coordinative or supramolecularaction. Also, the reversibility of redox property will bring an excellent reutilization.Third, we synthesized a novel electroactive diamine monomer (EDA) bearinganiline tetramer groups, and incorporated it facilely into poly(amic acid) backbones,yielding copolymers with oligoaniline side chains. The synthesized PAA copolymersexhibit a broad and strong absorption in the visible region and good solubility inorganic solvents. The PI films exhibit outstanding mechanical properties and excellentthermal stabilities with decomposition temperatures (at10%weight loss) between513and585oC in nitrogen atmospheres. Furthermore, the PAA copolymers also revealvaluable electrochromic char-acteristics with extremely high contrast value, lowswitching time and moderate coloration efficiency.Last, a well-defined multifunctional polyamide bearing pendent aniline tetramergroup has been synthesized via low temperature solution polycondensation. Theelectrochromic performance of oligoaniline shows the optical change in absorptivitydepends on the redox states. As we know, an absorptivity change is accompanied by aconcomitant change in refractive index. By taking advantage of this effect, we havefabricated electrochemically responsive optical diffraction gratings. A single stepfabrication of surface relief gratings based on azo-chromophore involves in theprocedure.