The strong interaction between poly(vinyl chloride) and a new eco-friendly plasticizer: A combined experiment and calculation study

Hydrogenation has been proved to be an efficient way to remove the toxicity of phthalate plasticizer. However, other influences of this hydrogenation are still unknown. Here we chose di-2-ethylhexyl phthalate (DOP) and di(2-ethylhexyl) cyclohexane-1,2-dicarboxylate (DEHHP) to study the influence on interaction with poly(vinyl chloride) (PVC). By combining experiment and calculation, we found the interaction was stronger in PVC/DEHHP than in PVC/DOP. Low-Field 1H NMR results showed that PVC chains could restrict much more DEHHP molecules than DOP. FTIR results showed that the interaction exists in form of hydrogen bonding complex, and it was stronger in PVC/DEHHP than in PVC/DOP system. Combined with FTIR results, theoretical calculation results revealed the three-center hydrogen bonded structure of the complex. Both the proportion and the binding energy of pre-complex in DEHHP are much larger than in DOP. Here, the hydrogenation-induced change of interaction was elucidated systematically and could be generalized to other phthalate plasticizers.