Carbohydrate Polymers 90 (2012) 901–907 Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers jo u rn al hom epa ge: www.elsevier.com/locate/carbpol Synthesis of graft copolymer (CgOH-g-AGA): Physicochemical properties, characterization and application Arpit Sand, Dinesh Kumar Mishra, Vijay Shankar Pandey, Madan Mohan Mishra, Kunj Behari ∗ Polymer Science Research Laboratory (PSRL), Department of Chemistry, University of Allahabad, Allahabad 211002, India a r t i c l e i n f o Article history: Received 3 April 2012 Received in revised form 21 May 2012 Accepted 10 June 2012 Available online 18 June 2012 Keywords: Graft copolymer -Carrageenan 2-Acrylamidoglycolic acid Swelling Flocculation Metal ion uptake a b s t r a c t A graft copolymer of -carrageenan and 2-acrylamidoglycolic acid (CgOH-g-AGA) was synthesized via free radical polymerization initiated by potassium peroxymonosulphate/malonic acid redox pair. For affording maximum percentage of grafting, optimum conditions were determined by varying the con- centrations of -carrageenan, 2-acrylamidoglycolic acid, potassium peroxymonosulphate, malonic acid, hydrogen ion, time and temperature. The swelling, metal ion uptake and flocculation studies were inves- tigated with water, three metals (Ni 2+ , Pb 2+ and Zn 2+ ) solutions, coal (coking and non-coking) suspensions, respectively. Both, polymer backbone and its corresponding graft copolymer samples were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, many researchers and scientists have paid their attention to develop a variety of advanced and hybrid polymeric materials (Ali, Saikia, & Sen, 1997; Liu et al., 2009; Pan, Zhao, & Lee, 2011; Yu, Dean, & Li, 2006) for their industrial applications. Of these materials, one of the most important materials is graft copoly- mer because of great importance in many applications (Baron, Rodriguez-Hernandez, Ibarboure, Derail, & Papon, 2009; Guan, Luo, Qiu, & Tang, 2010; Mostafa, Samarkandy, & El-Sanabary, 2011; Xun et al., 2011). Considerable interest has also been shown previously from our laboratory to synthesize different graft copolymers based on natural polymers chemically modified by synthetic monomers (Mishra, Tripathy, & Behari, 2008; Mishra, Tripathy, Srivastava, Mishra, & Behari, 2008; Mishra, Sand, Mishra, Yadav, & Behari, 2010; Sand, Yadav, Mishra, & Behari, 2010; Sand, Yadav, Mishra, Tripathy, & Behari, 2011; Srivastava, Mishra, Tripathy, & Behari, 2009; Yadav et al., 2012). The free radical polymerization is one of the best and convenient among various approaches (Abdel-Razik, 1997: Cardona, George, Hill, Rasoul, & Maeji, 2002; Dargaville, George, Hill, & Whittaker, 2003; Egboh, George, & Barrie, 1984) by which the desirable properties of synthetic monomers are mani- fested in the polymers. The present study is directed towards the ∗ Corresponding author. Tel.: +91 532 2545354. E-mail address: r dineshmishra@rediffmail.com (K. Behari). synthesis of a new graft copolymer (CgOH-g-AGA) of -carrageenan and 2-acrylamidoglycolic acid. Carrageenan is a generic name for a family of polysaccharides (Stanley, 1987), obtained by from differ- ent species of Rhodophyta: Gigartina, Chondrus crispus, Eucheuma and Hypnea. These polysaccharides are traditionally split into six basic forms: Iota ()-, Kappa ()-, Lambda ()-, Mu ()-, Nu ()- and Theta ()-carrageenan. In which, -carrageenan is predomi- nantly obtained by extraction of the tropical seaweed Kappaphycus alvarezii, known in trade as Eucheuma cottonii (or simply cot- tonii) (Rudolph, 2000). The structure of -carrageenan is made up of  (1→4) d-galactose-4-sulphate and  (1→3) 3,6-anhydro-d- galactose (Harding, Day, Dhami, & Lowe, 1997; Tha’nh et al., 2002). It is used in various food products as a thickening, gelling and stabilizing agent (Clark & Ross-Murphy, 1987; Glicksman, 1979) and non-food products such as pharmaceutical, cosmetics, print- ing and textile formulations (De Ruiter & Rudolph, 1997; Imeson, 2000; Joneja, Harcum, Skinner, Barnum, & Guo, 1999). Although - carrageenan has wide range of uses and applications, it suffers from certain drawback like biodegradability, which limits its uses. There- fore, 2-acrylamidoglycolic acid is, hydrophilic in nature, chosen as monomer to synthesize a new hybrid material of graft copolymer. Since, 2-acrylamidoglycolic acid also refers to a class of acrylamides containing OH, COOH and CONH functional groups, it also shows excellent selectivity in separating apatite from siliceous gangue (Nagaraj, Rothenberg, Lipp, & Panzer, 1987). Consider- ing all of these fascinating applications of 2-acrylamidoglycolic acid and -carrageenan, an attempt is made to synthesize hitherto unreported modified graft copolymer (CgOH-g-AGA) 0144-8617/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.carbpol.2012.06.018