Synthesis, characterization, and thermal degradation studies on group VIA derived weak-link polymers

Polymers containing group VIA derived weak links, viz. poly(styrene disulfide) (PSD), poly- (styrene tetrasulfide) (PST), and poly(styrene diselenide) (PSDSE), have been synthesized. The polymers and PST were characterized by NMR, IR, UV, TGA, and fast atom bombardment m w spectrometric (FABMS) techniques. The presence of different configurational sequences in PSD and PST were identified *3C NMR spectroscopy. PSDSE, being insoluble in common organic solvents, was characterized using -state lac NMR (CP-MAS) spectroscopy. Thermal degradation of polymers under direct pyrolysis-mass (DP-MS) conditions revealed that all the polymers undergo degradation through the weaklink . A comparative study of the pyrolysis products of these polymers with that of poly(styrene ) (PSP) revealed a smooth transformation down the group with no monomer (styrene or oxygen) in PSP to only styrene and selenium metal in PSDSE. This trend of group VIA is explained from energetics of the C-X bond (X = 0, S, and Se) which also seems to be important in addition to the weak -X bond cleavage. In PSP and PSD, the behavior is also explained from the energetics of the alkoxy and radicals. The unique exothermic degradation in PSP compared to endothermic degradation in PSD PSDSE is explained from the nature of the producta of degradation.