(488ab) Synthesis, Characterization, and Kinetic Modeling of Renewable Bioplastics

A green polymerization method, melt polycondensation, using monomers available from renewable biomass, 1,3-propandediol (PDO), malonic acid (MA), and itaconic acid (IA), was investigated. PDO-MA and PDO-IA were copolymerized with reaction temperatures between 125 and 175 °C and reaction times between 2 and 32 h producing polymers at 1-98 wt.% yields. Fourier transform infrared (FTIR) spectroscopy showed the copolymers contained ester functional groups as initially predicted, and also anhydride and ether functional groups. X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance (H-NMR) was used to confirm the chemical composition. Gel-permeation chromatography (GPC) showed both single modal and bi-modal distributions of molecular weights from 0.2 kDa to 80 kDa. Changes in functional group concentrations, molecular weight, and polydispersity index were examined by FTIR and gel permeation chromatography (GPC) with reaction temperature showing the strongest effect on the molecular weight and chemical structure. A simplistic kinetic model was developed, using Flory's fundamental principles as a starting point [1,2], for the polycondensation of PDO-MA and PDO-IA. To account for water and other small by-products, a Szabo-Rethy correction was used in the model [3]. For PDO-IA, the inclusion of additional branching parameters was needed. Using cascade theory developed by Flory for branched polymers, branching probability and the sol-gel point were predicted for PDO-IA [4,5].