Modular Preparation of Discrete Polyesters through Iterative Growth

Abstract

Discrete macromolecules featuring precise chemical structures and uniform chain lengths are ideal model systems for resolving fundamental principles with an exceedingly high resolution. This work develops a robust approach to prepare orthogonally protected monomers for the convergent synthesis of discrete sequence-defined polymers. Malic acid derivatives bearing hydrophilic, hydrophobic, or omniphobic substituents were designed and synthesized. All of these monomers have the same chemical features and can be modularly connected following the same chemistry. Discrete polyesters with diverse composition and programmable monomer sequence, including homopolymers, diblock/triblock copolymers, and alternating polymers, were readily prepared. The resultant discrete species were fully characterized by nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF MS). This study expands the diversity of monomers that can be applied in iterative growth, which is expected to serve as an efficient synthetic platform for precise macromolecular engineering.