Synthesis and characterization of eco‐friendly poly(ε‐caprolactone) plasticizer facilitating phthalate‐free polyvinyl chloride with novel star/net‐shaped structures

Abstract

AbstractPotential migration and toxicity limited applications of traditional plasticizers like bis(2‐ethylhexyl) phthalate (DEHP) in food packing and medical machinery and so forth. Safe and feasible bio‐based plasticizers have recently moved into the limelight of research hotspot. Here, we designed series polyester plasticizers of various branches with star‐shaped poly(ε‐caprolactone) (SPCLs) and net‐shaped poly(ε‐caprolactone) (NPCLs) structures by one‐pot solvent‐free synthesis with glycidol and polyglycerol as initiators. Structures of SPCLs and NPCLs were further verified by FTIR, 1H NMR, and 13C NMR. Moreover, the properties of the plasticizers and plasticized PVC were evaluated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and tensile test. PVC films plasticized with the SPCLs or NPCLs exhibited increased plasticizing effect, compatibility, flexibility and cold resistance. The lowest Tg value of plasticized PVC samples (PVC/NPCL1‐C4) was −45.3°C, which made the plasticization efficiency reach 122.5%. In particular, PVC/SPCLs‐C4 (SPCL2‐C4) had 107% higher elongation at break than PVC/DEHP. Meanwhile, the initial decomposition temperature Ti value of the PVC blends maximum increased from 240 to 328°C when DEHP was completely replaced by SPCLs or NPCLs, indicating improved thermal stability of the plasticizer. Overall, “green” plasticizers with fining topological branch design would be promising to partially replace petroleum‐based plasticizers.