Synthesis and characterization of biopolymer‐based electrical conducting graft copolymers

Abstract

The naturally occurring Guar gum (GG) was chemically modified with polyaniline (PANI) using ammonium persulfate (APS) as oxidant/initiator in acidic condition. The representative graft copolymer was characterized using UV–vis, FTIR, H1 NMR, XRD, TGA, and SEM taking GG and PANI as reference. The affinity of the upper limit for the graft copolymerization has been extensively studied by varying different chemical and physical parameters. All the findings have been discussed, and proposed a plausible mechanism for the graft copolymerization. The grafted GG exhibited hybrid properties of biopolymer as well as PANI, and has electrical conductivity in the range of 1.6 × 10−2 S/cm at room temperature. The electrical conductivity of the grafted biomaterial was quite sensitive with pH, and it could be interesting to combine a biopolymer, isolated from the natural resources with synthetic polymer from petrochemical origin, and yielded an eco‐friendly material of high performance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Gum ghatti based novel electrically conductive biomaterials: A study of conductivity and surface morphology

“…The copolymer formed in this way consisted of a crosslinked structure [30]. Various authors reported free radical copolymerization of vinyl monomers with carbohydrate polymers using peroxydisulfate, a chain mechanism is involved due to the formation of sulphate ion radicals, which are well known ion chain carriers for the graft copolymerization [26,[31][32][33].…”

“…They initiate the oxidative polymerization of aniline. The macro radical semi-ipn* may be generated by the abstraction of H by the growing PANI ion radical in the acidic medium, which may add onto the semi-ipn macro radicals generating new radical semi-IPN* and these chains will be grow and combined with other semi-IPN* chains to give a graft copolymer ( Figure 3) [26,31]. Preparation of Gg-cl-poly(AAm-ipn-aniline) conducting hydrogel is schematically displayed in Figure 4.…”

“…The electrical conductivity measurements were made on compressed circular pellets (mass ~0.2 g, diameter = 8 mm, thickness = 1±0.07 mm, pressure = 8 t/cm 2 ). The resistivity of the sample was calculated using the Equation (1) [26]: (1) where ", R, A, and l are resistivity [#·cm], resistance [#], area of the pellet [cm 2 ], length of the pellet [cm], respectively. Conductivity can be computed using the relationship, # = 1/", where # is the conductivity, and " the resistivity of the sample.…”

“…Grafting is clear from the TGA that the Gg-cl-poly(AAm-ipn-aniline) has more thermal stability than the gum ghatti and Gg-clpoly(AAm) both [26]. The percent of weight losses at the selected temperatures are listed in Table 3.…”

“…Crosslinked hydrogels based on gum ghatti were studied to determine their absorbency and biodegradability [21,22]. Various authors synthesized electrical conducting hydrogels based on different polysaccharides and polyaniline through graft copolymerization [23][24][25][26]. The produced materials have found applications in the area of biosensors and gas sensors [3,25].…”