Graft Copolymerization of Vinyl Monomers on Modified Tragacanth via ATRP Method

In recent years, modification of natural polymers to employ in different fields of applications has attracted much more attention [1]. Because of biodegradability and low-cost, biopolymers are being considered as suitable polymeric precursors which can be converted to valuable materials [2]. One of the most common ways to employ biopolymers is to modify the outer surface of the biopolymer in order to prepare the backbone for graft copolymerization. Among polymerization methods, living radical polymerization is much more common, since it results in a graft copolymer with narrow polydispersity [3]. Atom transfer radical polymerization (ATRP) is a popular method among other living radical polymerization methods, which is used in this study to prepare tragacanth graft copolymers. In the present work, the outer surface of tragacanth was bromoacetylated using two different methods: grinding method and dispersion medium method. The acyl content for each product was calculated in order to determine the active polymerization sites. Different vinyl monomers such as acrylic acid and acrylamide were then polymerized on the bromoacetylated tragacanth using ATRP method. Results showed successful grafting on the modified tragacanth backbone. Different studies such as FT-IR, TGA and AFM analyses proved this issue. Besides, the solubility of each product in different solvents was investigated.