SWBC pretreatment
The untreated SWBC feedstock (Fig. S1a) was added to three vials that were pretreated by heating in PAA solution at 80 °C for 3 h, and then freeze-dried. As shown in Fig. S1b, PAA-pretreated SWBCs are bulkier and whiter than untreated SWBC. The increased white intensity of the pretreated SWBC is caused by PAA, which acts as a strong bleaching agent.