Scheme 4. Synthesis and Polymerization of MTA.

Experimental procedure for nitrile hydrolysis (see the SI, pp. S16–S17), oxidation (see the SI, pp. S17–S18), carboxylation (see the SI, p. S17), and polymerization (see the SI, p. S18). The 2.4 mmol scale hydrolysis of 5 to 7 was conducted with 5 obtained from noble fir, and the following oxidation step was conducted with the noble fir-derived 7. The MTA used for the polymerization was obtained from a reported procedure.⁶¹ Qualitative assessment by ¹H- and ¹³C-NMR analysis of the hydrolysis, oxidation, and carboxylation steps indicate a high purity of the respective compounds 7 and 8. Purification methods used: hydrolysis step (acid–base wash), oxidation step (decantation with AcOH, H₂O, and pentane), carboxylation step (acid–base wash), polymerization (no purification). The glass-transition temperature was evaluated with differential scanning calorimetry (DSC), while the decomposition temperature was analyzed with thermogravimetric analysis (TGA) (see the SI, Figures S6 and S7). The error was measured to be ±1.0 °C for DSC analysis and ±1.7 °C for TGA.