Synthesis, Characterization and Thermal Properties of Some Acrylamide and 𝐶𝑖𝑠-۲-Butene-۱, ۴-Diol Copolymers Using CAN as Initiator

In this study, poly (acrylamide-co-cis-۲-butene-۱, ۴-diol) was synthesized by polymerization of various molar ratios of acrylamide and cis-۲-butene-۱, ۴-diol using ceric ammonium nitrate (CAN) as redox initiator. The copolymer then has been modified through incorporating of linear alkyl ester chains (C۸ and C۱۸) into copolymer by esterification reaction as melts using pTsOH as catalyst. Resulting copolymers were purified and characterized by FT-IR, NMR, and GPC. All analyses indicate that cis-۲-butene-۱,۴-diol has the ability to act as both a monomer and a reducing agent which confirms the validity of the proposed mechanism. The reaction conditions have been varied and the best yield of copolymer is ۶۵.۱% under these following optimum reaction conditions; ۸ mL of CAN solution, ۲.۴´۱۰-۳ mmol of acrylamide, ۱۹.۶´۱۰-۳ mmol of cis-۲-butene-۱,۴-diol, ۶ hours reaction time, and ۵۰ °C reaction temperature. GPC and hydroxyl number determination showed acrylamide units consist of the larger portion in the copolymer chains. Thermal characterization of copolymers was also investigated using TGA, DTG, and DCS analysis. TGA/DTG revealed multi-stage decomposition, while DSC exhibited a shift in the Tg peak after reaction with aliphatic carboxylic acids. Kinetics of thermal decomposition was also investigated using models of the Coats–Redfern and the second order of the chemical reaction was found to be more appropriate to describe the reaction model for the thermal degradation of copolymers with R۲ correlation up to ۹۹.۷%. The activation energy in the region of Tmax also increased by adding longer alkyl ester group to the copolymer, which can contribute to the improvement of its thermal stability.

Keywords:

thermal properties , 𝐶𝑖𝑠-۲-butene-۱ , ۴-diol copolymers , Thermal stability , Inhibitor , Copolymer synthesis