Polymer sequencing via unsupervised learning of pyrolysis-mass spectra

A sequence—an arrangement of monomers—dominates polymer properties, as best exemplified by proteins; however, an efficient sequencing method for synthetic polymers has not been established yet. Herein, we propose a polymer sequencer based on mass spectrometry of pyrolyzed oligomeric fragments. By interpreting an observed fragment pattern as one generated from a mixture of sequence-defined copolymers, sequencing can be simplified to compositional analysis. Our key development is a reference-free quantitative mass spectrometry. The reference spectra of the hardly synthesizable sequence-defined copolymers were not actually measured but virtually inferred via unsupervised learning of the spectral dataset of easily synthesizable random copolymers. The polymer sequencer quantitatively evaluates complex sequence distribution in versatile multi-monomer systems, which would allow sequence–property correlation studies and practical sequence-controlled polymerization.