Acetone

PGS pre-polymers (pPGS), sebacic acid powder (Sigma Aldrich, Seoul, Korea), and glycerol (>99.5%, Sigma Aldrich, Seoul, Korea) were prepared according to the previously published method [58 (link)]. A 1:1.5 molar mixture of sebacic acid and glycerol was placed in a three-neck round bottom flask. The monomers were heated at 120 °C in a nitrogen environment for 24 h. The synthesized solution was filtered using cold acetone (Sigma Aldrich, Seoul, Korea) to remove the loosely cross-linked monomers and the filtrate was used for experiments. The filtrate was reheated and a few drops of N,N-dimethyl formamide (DMF) solvent (Sigma Aldrich, Seoul, Korea) were added to make a homogeneous solution. The PVA solution was prepared by dissolving 1.5 g of PVA powder (Mw~27,000, Sigma Aldrich) in 10 mL of distilled water at 90 °C under continuous stirring for 4 h. Both solutions were blended at various loading ratios of PGS and PVA (2:1.5, 2:1, 2:2 (v/v)) at 50 °C for 30 min. The solution was processed for wet spinning, in which the coagulation bath contained acetone (Sigma Aldrich, Seoul, Korea) and water with an acetone concentration of 70% (v/v). The AuNPs (20 nm in diameter, Sigma Aldrich, Seoul, Korea) were incorporated in a composite conductive microfiber solution.