a, The NLCO source samples are shown to be a mixture of monomers, dimers, trimers, tetramers, and other oligomers (blue solid line, peak appearing at longer retention time represents shorter chain length). In step-polymerization processes, when the extent-of-reaction is less than 0.9, then monomers dominate the overall molar fraction. For comparison, LC macromers (used in the supporting experiment in Methods) synthesized following the schemes of Ware et al.10 are also included in the plot; the latter show longer mean chain length and very few (if any) short-chain components (red dashed line). Furthermore, since our system is made in an aqueous solution, the polymerization rate is expected to be slower. For reference, the black dotted line shows the peak for pure RM82 monomer. b, Calculated from SEC data (example in (a)), the number-average molecular weight (, blue solid square) and polydispersity index (PDI, red solid circle) of the NLCOs are shown as function of oligomerization time. Both and PDI increase with oligomerization time. The dotted (for ) and dashed (for PDI) curves are to guide the eye. (For comparison, the LC macromer synthesized following the schemes of Ware et al.10 and used in Methods section, “Macromer-monomer mixing experiments”, has ≈ 6,900 Da and PDI ≈ 1.3.)