| Poly(ethylene terephthalate) (PET) is one of the world's most important commodity plastics. The largest volume applications of PET include textile fiber, tire cord, and packaging materials. There are many opportunities for improving the properties of PET that are associated with its various applications. We address three of the major application driven issues in PET: Increasing the optical brightness, increasing the crystallization rate, and enhancing the optical clarity through inhibition of crystallization. Each of the projects is summarized below.; A new class of monomeric fused aromatic fluorescent brightening agents based on pyrene and anthracene have been designed and synthesized. The monomers: dimethyl 1,6-pyrene dicarboxylate, dimethyl 1,8-pyrenedicarboxylate, dimethyl 2,7-pyrenedicarboxylate, 1,9-bis(2-carboxybenzoyl)pyrene dimethyl ester, dimethyl 2,6-anthracenedicarboxylate, dimethyl 2,7-anthracenedicarboxylate and dimethyl 9,10-anthracenedicarboxylate were copolymerized with poly(ethylene terephthalate) and their optical properties were assessed. All of the polymers gave blue fluorescence with the copolymer containing dimethyl 1,6-pyrenedicarboxylate being the brightest.; The synthesis of 2,7-substituted pyrene derivatives needed for the optical brightening project and for the crystallization rate enhancement project posed unique challenges. Optimized synthetic procedures for these compounds were developed. Pyrenes derivatized in the 2- and 7-positions were prepared by reduction of pyrene to 4,5,9,10-tetrahydropyrene followed by electrophilic aromatic substitution and re-aromatization. An optimized procedure is presented for hydrogenation of pyrene to provide 4,5,9,10-tetrahydropyene in high yield, which facilitates a convenient synthesis of dimethyl 2,7-pyrenedicarboxylate. |
