Monodisperse Oligoamides as Precise Precursors for Nylon via Solid-State Polycondensation

This study presents a scalable, solution-phase protocol for the synthesis of monodisperse oligoamides with nylon-4, nylon-6 and hybrid nylon-4/6 backbones, enabled by a group assisted purification strategy. For this, unnatural amino acid monomers are iteratively coupled onto a phosphonate-functional soluble support, yielding uniform oligomers bearing orthogonal functional end groups that allow their solid-state polycondensation (SSP). Pure monodisperse oligomer precursors of nylon-4 exhibits thermal limitations due to their low ceiling temperature, resulting in low molecular weight products after SSP. In contrast, incorporation of strategically positioned nylon-6 units effectively suppress backbiting and facilitates efficient SSP, producing well-defined nylon-4/6 copolymers. This unique design approach offers unprecedented control over the polyamide microstructure and establishes a versatile route toward polyamide synthesis with potential for customizing material properties.