Carbohydrate Polymers 88 (2012) 1407–1413 Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers jo u rn al hom epa ge: www.elsevier.com/locate/carbpol Amine activators influence on grafting reaction between methacrylic acid and starch Vladimir Nikolic a,∗ , Sava Velickovic b , Aleksandar Popovic c a Innovation Center, Faculty of Chemistry, Belgrade University, Studentski trg 12-16, Belgrade 11000, Serbia b Faculty of Technology and Metallurgy, Belgrade University, Karnegijeva 4, Belgrade 11000, Serbia c Faculty of Chemistry, Belgrade University, Studentski trg 12-16, Belgrade 11000, Serbia a r t i c l e i n f o Article history: Received 3 January 2012 Received in revised form 2 February 2012 Accepted 13 February 2012 Available online 22 February 2012 Keywords: Starch Methacrylic acid Graft copolymer Amine activator a b s t r a c t The aim of this work was synthesis of grafted copolymers of poly(methacrylic acid) and starch (PMAA- graft-starch) with high percentage of grafting, G (%). The effect of temperature (55–75 ◦ C), concentration of methacrylic acid monomer (0.775–1.452 mol/dm 3 ), amount of initiator potassium persulfate (PPS) (0.00075–0.0025 mol), reaction time (30–270 min) and nature and amount (0.001–0.005 mol) of amine activator on percentage of grafting were investigated. The following amine activators were used: N,N-dimethylaminoethanol, N,N-diethylaminoethanol, triethylamine, propylamine, iso-butylamine, pentylamine, hexylamine, 4-(2-hidroxyethyl) morpholine and 1-(2-hidroxyethyl) piperazine. The graft copolymer was characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. The highest G was 40.92%. Reaction conditions were as follows: 10.00 g of starch, monomer concentration was 0.775 mol/dm 3 , temperature of 70 ◦ C, the amount of PPS was 0.001 mol. The 4-(2- hidroxyethyl) morpholine was used as amine activator in amount of 0.001 mol. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Starch is a natural carbohydrate. It is composed of lin- ear polysaccharide molecules (amylose) and branched molecules (amylopectin). It is accumulated in plants. Starch is desirable as an environmentally friendly alternative material for making biodegradable plastics, because it is a natural polymer that can be degraded by microorganisms. It is inexpensive and obtained from renewable resources. Starch is also suitable for blending with other polymers (Abdel-Hatiz, 1997; Bernkop-Schnurch, Konig, Leitner, Krauland, & Brodnik, 2002; Bocchini, Battegazzore, & Frache, 2010; Shin, Narayan, Lee, & Lee, 2008; Shin, Jang, & Kim, 2011; Vaidya, Bhattacharya, & Zhang, 1995; Yang, Bhattacharya, & Vaidya, 1996; Zhou et al., 2009). Composites of starch and poly(methacrylic acid) are commonly used for medical applications for drugs delivering to specific locations in the body (Clausen, & Berknop-Schnurch, 2001; El-Hag Ali, & AlArifi, 2009; McConnell, Short, & Basit, 2008). Chemical modification of starch via grafting of vinyl monomers is one of the most effective methods to incorporate desirable prop- erties into starch without sacrificing its biodegradable nature. Lee ∗ Corresponding author. Tel.: +381 11 3303805; fax: +381 11 3370387. E-mail addresses: nikolicv@chem.bg.ac.rs (V. Nikolic), sava@tmf.bg.ac.rs (S. Velickovic), apopovic@chem.bg.ac.rs (A. Popovic). and Cho (1998) reported that methyl methacrylate (MMA) can be graft copolymerized onto corn starch by emulsion polymerization. Razi, Qudsieh, Yunus, Ahmad, and Rahman (2001) used potassium persulfate (PPS) as initiator for grafting MMA onto sago starch. Poly(acrylamide) can be grafted with starch (Kiatkamjornwong, Mongkolsawat, & Sonsuk, 2002; Singh, Tiwari, Pandey, & Singh, 2006; Willett, & Finkenstadt, 2003; Wu, Wei, Lin, & Lin, 2003). Polystyrene graft starch copolymers can be obtained by suspension polymerization (Kaewtatip, & Tanrattanakul, 2008), emulsion poly- merization (Cho, & Lee, 2002), 60 Co radiation (Fanta, Burr, Doane, & Russell, 1977; Henderson, & Rudin, 1981; Kiatkamjornwong, Sonsuk, Wittayapichet, Prasassarakich, & Vejjanukroh, 1999) and also in presence of different initiators (Graaf, & Janssen, 2000; Janarthanan, Yunus, & Ahmad, 2003; Singh, & Sharma, 2007). Another chemical modification of starch is grafting starch with biodegradable polymers, such as poly(lactide) (Chen et al., 2005) and polycaprolactone (Hang, Yu, Ma, & Jin, 2005; Rutot, Degee, Narayan, & Dubois, 2000). PMAA-graft-starch copolymers can be obtained by using dif- ferent initiator systems such as potassium persulfate (Khalil, Mostafa, & Hebeish, 1993), ammonium peroxydisulfate (Abo- Shosha, & Ibrahim, 1992), manganese (IV)–acid system (Khalil, Mostafa, & Hebeish, 1990), hydrogen peroxide–ferrous ammo- nium sulfate (Vazquez, Goni, Gurruchaga, Valero, & Guzman, 1989), KMnO 4 /citric acid (Mostafa, 1995), tetravalent cerium (Ce 4+ ) 0144-8617/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2012.02.027