Affiliation:
1. Department of Chemistry Colorado State University Fort Collins CO 80523-1872 USA
2. Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Road Evanston IL 60208-3113 USA
3. Department of Chemistry and the Trienens Institute for Sustainability and Energy Northwestern University 2145 Sheridan Road Evanston IL 60208-3113 USA
Abstract
AbstractGeminal (gem−) disubstitution in heterocyclic monomers is an effective strategy to enhance polymer chemical recyclability by lowering their ceiling temperatures. However, the effects of specific substitution patterns on the monomer's reactivity and the resulting polymer's properties are largely unexplored. Here we show that, by systematically installing gem‐dimethyl groups onto ϵ‐caprolactam (monomer of nylon 6) from the α to ϵ positions, both the redesigned lactam monomer's reactivity and the resulting gem‐nylon 6’s properties are highly sensitive to the substitution position, with the monomers ranging from non‐polymerizable to polymerizable and the gem‐nylon properties ranging from inferior to far superior to the parent nylon 6. Remarkably, the nylon 6 with the gem‐dimethyls substituted at the γ position is amorphous and optically transparent, with a higher Tg (by 30 °C), yield stress (by 1.5 MPa), ductility (by 3×), and lower depolymerization temperature (by 60 °C) than conventional nylon 6.