Fig. 1

Raman spectra and sol–gel transition of PASP-SH and PASP-SS. a Raman spectra of PASP, reduced state PASP-SH and oxidised state PASP-SS; b detailed spectra of PASP-SH and PASP-SS in the range of 400–800 cm⁻¹; c rotating rheology measurement of reversible redox-induced sol–gel transition of PASP-SH; the upper left illustration shows oxidised PASP-SS gel, and the lower right illustration shows reduced PASP-SH sol