Cross-linked PMMA-based bifunctional amino derivatives: An experimental and DFT study

The main purpose of the present study is to investigate the role of 1,12-diaminododecane and 4,4-diaminobiphenyl, as bifunctional amino derivatives, on the properties of poly(methyl methacrylate) (PMMA). Cross-linked PMMA derivatives of different degrees (2, 5, 10, 20, 30, 50, and 70 mass%) were synthesized by the interaction of neat PMMA with these two cross-linking agents through a polycondensation technique. FT-IR probes the possible interaction between the carbonyl (C=O) group of PMMA and the amino group of the diamine compounds. The change in the degree of crystallinity from one polymer to another is affected by the ratio and type of cross-linking. The surface morphology is dramatically changed by increasing the degree of cross-linking as evidenced from the SEM images. A major mass loss between 209 and 471 degrees C was observed from the TG curve of C-PMMA-H-2, whereas C-PMMA-ph(2) showed a major mass loss between 223 and 538 degrees C. A significant change in the thermal degradation behavior of cross-linked polymers was investigated at high cross-linking degrees. All products showed a final decomposition temperature (FDT) higher than pure PMMA. Considering the best result, FDT increased from 390 degrees C for pure PMMA to 577 degrees C for C-PMMA-H-4 and 607 degrees C for C-PMMA-ph(7). Moreover, a theoretical thermochemical analysis of the monomeric cross-linked isodesmic reaction was performed using density functional theory (DFT). The heat of formation of reactants and products was calculated and analyzed. The study, also, showed that the reactions are endothermic and spontaneous in the reverse direction at all temperatures. [GRAPHICS] .