UC Santa Cruz

Copper-free azide-alkyne click chemistry is utilized to covalently modify polyvinyl chloride (PVC). Phthalate plasticizer mimics di(2-ethylhexyl)-1H- triazole-4,5 dicarboxylate (DEHT), di(n-butyl)-1H-1,2,3-triazole-4,5- dicarboxylate (DBT), and dimethyl-1H-triazole-4,5-dicarboxylate (DMT) are covalently attached to PVC. DEHT, DBT, and DMT have similar chemical structures to traditional plasticizers di(2-ethylhexyl) phthalate (DEHP), di(n-butyl) phthalate (DBP), and dimethyl phthalate (DMP), but pose no danger of leaching from the polymer matrix and forming small endocrine disrupting chemicals. The synthesis of these covalent plasticizers is expected to be scalable, providing a viable alternative to the use of phthalates, thus mitigating dangers to human health and the environment. Covalently attached mimics of conventional phthalate plastacizers are synthesized on modified PVC by simple and scalable chemistry. Substitution of some of the chloride by azide, followed by thermal Huisgen cycloaddition with dialkyl acetylenedicarboxylates forms pendant triazoles bearing ortho esters resembling phthalate diesters. This copper-free cyclization is demonstrated at room temperature: first on small molecule models, then on PVC. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.