Non-Migratory Phthalates and Phthalate Mimics
Phthalate plasticizers are currently used on the million tons / year scale to convert inherently brittle polyvinyl chloride to form a wide variety of heat-extrudable, pliable consumer products. The most common phthalate plasticizer is DEHP:
Development of a substitute for Phthalate Plasticizers
Using our Nitroxide Mediated Polymerization (NMP), which is regularly carried out using styrene, we reasoned that vinyl phthalate esters should behave as substituted styrenes in NMP. We demonstrated that a variety of macromolecular plasticizers can be produced, as both homopolymers and random copolymers.
R. Braslau,* F. Schäffner, A. Earla “Polymeric phthalates: potential non-migratory macromolecular plasticizers,” Journal of Polymer Science Part A: Polymer Chemistry, 2013, 51, 1775-1184. doi: 10.1002/pola.26485.
• Polymerization of Vinyl Phthalate Esters to form Macromolecular Plasticizers
• Triazole Analogues of Phthalate Plasticizers covalently linked to PVC
Traditional plasticizers are mixed with granular PVC and melted into a matrix of PVC and plasticizer, from which building materials, clothes, food packaging, and medical supplies (ex. blood bags) are produced. The phthalates migrate out of these commodity products: if absorbed or ingested, they are metabolized to form endocrine signaling compounds, resulting in a variety of diseases including cancer, sexual malformation, and obesity.
Looking for an inexpensive method to attach phthalate plasticizers to PVC, we envisioned that a "click" reaction between an azide and acetylene dicarboxylates would form triazoles bearing ortho esters, as phthalate mimics covalently attached to PVC. This copper-free click reaction between azide and acetylene dicarboxylates occurs under mild conditions, making this attractive to industry.
A. Earla, R. Braslau* “Covalently Linked Plasticizers: Triazole Analogues of Phthalate Plasticizers Prepared by mild Copper-free “Click” Reactions with Azide-functionalized PVC,” Macromolecular Rapid Communications, 2014, 35, 666-671. doi: 10.1002/marc.201300865.
Efforts are underway to develop these triazole phthalate mimics as effective and inexpensive non-leachable phthalate alternatives.