Polymerization of Maleic Acid and Itaconic Acid Studied by FT-Raman Spectroscopy CHARLES Q. YANG, XIAOHONG GU Department of Textiles, Merchandising and Interiors, The University of Georgia, Athens, Georgia 30602 Received 1 May 2000; accepted 14 December 2000 Published online 18 April 2001 ABSTRACT: In this research, we used a new redox free radical initiation system con- sisting of potassium persulfate (K 2 S 2 O 8 ) and sodium hypophosphite (NaH 2 PO 2 ). In the presence of NaH 2 PO 2 , the thermal decomposition of K 2 S 2 O 8 is accelerated, and the temperature required for the formation of free radical is reduced. We polymerized maleic acid (MA) using the K 2 S 2 O 8 /NaH 2 PO 2 initiation system in an aqueous solution, and monitored the polymerization process with FT-Raman spectroscopy. The Raman spectroscopy data indicate the formation of a saturated carboxylic acid with the disap- pearance of the characteristic bands of MA as the thermal decomposition of K 2 S 2 O 8 progresses, thus indicating the formation of poly(maleic acid) (PMA). We also found that itaconic acid (IA) polymerizes in the presence of the new initiation system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 223–228, 2001 Key words: free radical polymerization; FT-Raman spectroscopy; itaconic acid; ma- leic acid; poly(maleic acid); poly(itaconic acid); reactive polymers; redox initiation INTRODUCTION Historically, MA and IA were extremely difficult to homopolymerize in comparison to other mono- substituted ethylenical acid monomers such as acrylic acid. In the past, PMA was synthesized by free radical polymerization of maleic anhydride in organic solvents, such as toluene, to form poly- (maleic anhydride) (PMAN) followed by hydroly- sis of PMAN to form PMA. 1–3 MA was polymer- ized in the presence of polyvinylpyrrolidone in water at 50 – 80°C with potassium persulfate (K 2 S 2 O 8 ) as an initiator to form a polymer com- plex with polyvinylpyrrolidone, in which the MA- to-vinylpyrrolidone ratio was 1 : 1. 4 Low molecu- lar weight PMA was also produced by polymeriz- ing alkali or ammonium salts of MA in aqueous solutions in the presence of peroxide initiators, 5,6 hydrogen peroxide and a polyvalent metal ion, 7 or water-soluble transition metal salts (such as iron sulfate heptahydra) as “promoters” in combina- tion with a water soluble initiator. 8 IA is easier to polymerize than MA because of its 1,1-disubstitution structure rather than the 1,2-disubstitution structure of MA. The first ho- mopolymerization of IA was reported in 1959, which was carried in a 0.5M hydrochloric acid solution with K 2 S 2 O 8 as an initiator, and it took several days to achieve 35% yield. 9 IA was poly- merized in methanol at room temperature with AIBN as a free-radical initiator, but it took 30 days for the polymerization process to reach 70% yield. 10 The derivatives of IA can be easily free- radical polymerized to give high molecular weight polymers. 11 In the past, a mixture of IA, MA, sodium hy- pophosphite (NaH 2 PO 2 ) and K 2 S 2 O 8 was applied to cotton fabric, and the treated cotton fabric ex- posed to elevated temperatures shows improved wrinkle resistance. 12–14 We identified a saturated Correspondence to: C. Q. Yang. Journal of Applied Polymer Science, Vol. 81, 223–228 (2001) © 2001 John Wiley & Sons, Inc. 223