Fishbone-Like Polymer from Green Cationic Polymerization of Methyl Eleostearate as Biobased Nontoxic PVC Plasticizer

Herein, fishbone-like poly(methyl eleostearate) (PME) plasticizer with high biobased content of near 90% was developed for the production of flexible poly(vinyl chloride) (PVC) by the green cationic polymerization of biobased monomer methyl eleostearate (ME) using renewable coconut oil as solvent, rather than the traditional alkyl halides with toxicity and volatility. The microstructure of PME was investigated by multiple technologies, and the results show that the favored microstructure of PME is the 9,10-unit because of the lower surface electrostatic potential and average local ionization energy near the double bond at C9 and C10. The acute toxicity test of PME shows that it is biologically safe and nontoxic. The effect of content of PME and the commercial plasticizer bis(2-ethylhexyl) phthalate (DOP) on the performance of plasticized PVC was investigated. When the weight ratio of PME and DOP is fixed at 1:1, PVC film presents higher stretchability (604.7% vs 309.1%) and enhanced strength (21.0 MPa vs 11.0 MPa) compared with PVC plasticized with DOP. A possible mechanism related to chain entanglements and dipole-dipole interaction is proposed. Further, as DOP is substituted with PME, PVC films show improved migration resistance with the weight loss being more than 75% lower after leaching in petroleum ether and olive oil.