The development of high dielectric (k) materials has generated enormous interest due to wide range of applications for rechargeable batteries, capacitors and other electrochemical devices [1]. Present research is focused on preparation and fabrication of nanostructured dopants such as nanoparticles, nanofibers, nanotubes, nanorods, and nanowires etc., for the improvement of dielectric, chemical and physical properties of polymer composites for various applications [2–3]. But due to low conductivity at room temperature, the use of such materials is limited and hence finding a suitable low cost material with a high dielectric constant (k) is crucial. Polystyrene, Polymethyl methacrylate, Polyvinylpyrrolidone, Polyvinyl alcohol, Polyacrylamide have been used as gate dielectric materials but the poor electrical strengths of these polymers lead to gate leakage current and poor device stability. Carbon-based materials have recently drawn more attention as fillers since these materials are known to enhance the mechanical and thermal properties of polymers [4]. Several reports in literature have focussed on using graphene oxide (GO) and graphene sheets, graphite nano-platelets and carbon nanospheres (CNS) as dopants for poly olefins, poly(acrylates), epoxy, elastomers and cellulose, chitosan, polyamide and poly(methyl methacrylate) etc[5].
Polyvinyl alcohol (PVA) is a transparent polymeric material consisting carbon chain as backbone and hydroxyl (OH) groups [6]. PVA shows good dielectric strength, fast charge transfer at electrode-composite interface in separator, supports for electrical and optical properties [7]. Polyacryl amide (PAM) is a hydrophilic polymer which is highly water-absorbent and forms a soft gel when hydrated and hence has gained a great extent of utility in wide range of industrial applications such as manufacturing of soft contact lenses, potable water treatment industry etc [8–9]. PAM hydrogel is low cost, non-toxicity, biological inertness, has good stability over mechanical and morphological properties [10–11].Carbon nanospheres (CNS) are attractive material for nanocomposites due to control over their morphology and properties which makes it an appealing material for adsorption, catalysis, and hydrogen storage or electronics material applications.
To enhance the dielectric properties of polymer nanocomposites, methods like blending plasticization, copolymerization and addition of salts are adopted[12]. Polymer blending technique has found a wide range of commercial applications in past couple of decades due to its ease-of-synthesis, cost-effectiveness and versatility[13]. Especially in recent decades, blending of polymers with carbon nanomaterials have grabbed attention due to their electrical conductivity, low cost and chemical stability[14].
One of the most used elemental nanomaterials is nanosilver, which is used to dope polymer composites and shows ill effects on humans [15]. Similarly, TiO2-based blend composites focus on few practical challenges like low conductivity, uniform dispersion in aqueous suspension [16]. But Carbon nanoparticles show good mechanical, electrical conductivity, heat conductivity properties. Carbon nano-materials have an advantage of being stable, nontoxic and environmentally friendly over other elemental nanomaterials. Different kinds of carbon nanoparticles in the form of nanotubes, nano flakes, nano rods, nano spheres have been synthesized till date and have been demonstrated to possess excellent blending properties compared to other nanomaterials. Amongst this carbon Nano spheres show potential application in optoelectronics, energy storage, sensors and encapsulating electrodes[17–19].
Numerous reports pertaining to the studies of carbon nanoparticles based blends have been published in past two decades. Ashwini Swaminathan et. al have investigated preparation and characterization of PVA/PAM/NH4SCN polymer film by ultrasound-assisted solution casting method for application in electric double layer capacitor[20]. Jin-Min Luo et al., studied on Hollow carbon nanospheres: syntheses and applications for post lithium-ion batteries [21]. Nitrogen doped hollow carbon nanospheres study by Hua Lin et al., showed a chemical approach toward preparing nitrogen-doped hollow carbon nanospheres [22].
In this work, we report the effect of CNS on PVA and PAM polymer nanocomposite on their structural and dielctric properties as well as the effect of temperature on them. The structural, thermal and morphological properties of CNS doped polymer nanocomposites has been studied using FT-IR and SEM techniques.