Microwave promoted synthesis of chitosan‐graft‐poly(acrylonitrile)

Abstract

Using microwave (MW) irradiation, polyacrylonitrile was grafted onto chitosan with 170% grafting yield under homogeneous conditions in 1.5 min in the bsence of any radical initiator or catalyst. Under similar conditions a maximum grafting of 105% could be achieved when the K 2 S 2 O 8 /ascorbic acid redox system was used as radical initiator in a thermostatic water bath at 35 Ϯ 2°C. The representative graft copolymer was characterized by Fourier transform infrared spectra, thermogravimetric analysis, and X-ray diffraction measurement, taking chitosan as a reference. The effects of such reaction variables as monomer/ chitosan concentration, MW power, and exposure time on the graft co polymerization were studied. A probable mechanism for grafting without the redox system under microwaves was proposed.

Peroxydisulfate initiated synthesis of potato starch-graft-poly(acrylonitrile) under microwave irradiation

“…Starch which is a low cost abundantly available renewable biopolymer on modification may develop properties comparable to synthetic petroleum-based polymers [1,2] Chemical grafting [3][4][5][6][7] is one of the popular methods for modifying structure and properties of biopolymers. Vinyl grafting on to the polysaccharides improves their shelf life against biodegradation, thermal stability and metal ion binding ability and therefore grafted polysaccharides have a wide range of industrial utility [8].…”

“…Main advantage is that it results in almost instantaneous bulk heating of materials in a homogeneous and selective manner. Under microwave irradiation grafting and homopolymerization have been studied without initiators [3,4] or in the presence of very low concentration of initiator [20,21] and this prompted us to undertake microwave promoted grafting of poly(acrylonitrile) onto potato starch using small concentration of ammonium peroxydisulfate as initiator.…”

Approaches for Functional Modification or Cross‐Linking of Chitosan

“…This study highlighted the feasibility of using chitosan for electrochemical biosensor applications [117]. Microwave irradiation has also been used for grafting chitosan with polyacrylonitrile [118]. The effects of reaction variables, such as monomer or chitosan concentration, microwave power, and exposure time on the graft copolymerization, were studied.…”

Synthesis and characterization of electrical conducting chitosan-graft-polyaniline

“…A chain mechanism [23] is involved due to formation of sulphate ion radicals (SO 4 -. ), which are well-known ion chain carriers for graft copolymerization.…”

“…Chi-tosan has found potential use in many areas, it is a brittle material and tends to absorb a quantity of moisture and to improve its toughness, solubility and rheological properties, graft copolymerization of a vinyl monomer onto chitosan chains is commonly employed for several applications. Therefore, chitosan as a low cost, degradable, biocompatible, high molecular weight, branched biopolymer with unique physiochemical properties [16] (presence of -OH and -NH 2 groups offers self doping) is a good candidate to introduce functional groups in PANI, and enhance its selectivity for chemical sensors. In the present study, PANI was grafted on to chitosan in order to synthesize electrically conducting tailor-made material having good pH-switching properties.…”