Thiol-Ene Networks from Sequence-Defined Polyurethane Macromers.

To date, scalability limitations have hindered the exploration and application of sequence-defined polymers in areas such as syn-thetic plastics, fibers, rubbers, coatings, and composites. Additionally, the impact of sequence on the properties of cross-linked networks remains largely unknown. To address the need for synthetic methods to generate sequence-defined materials in gram quantities, we have developed a strategy involving inexpensive and readily functional vanillin-based monomers to assemble se-quence-defined polyurethane oligomers via sequential reductive amination and carbamation. Three oligomers were synthesized with monomer sequence precisely dictated by the placement of reactive side chains during the reductive amination reaction. Avoiding excessive chromatographic purification and solid- or liquid-phase supports enabled synthesis of sequence-defined oligo-mers on the gram-scale. Remarkably, sequence was shown to influence network topology upon cross-linking as evidenced by se-quence-dependent rubbery moduli values. This work provides one of the first examples of a scalable synthetic route towards se-quence-defined thermosets that exhibit sequence-dependent properties.