Holocellulose fibers were obtained

Holocellulose fibers were obtained using a PAA treatment,adapted with some modifications from a previous work.32 Softwood spruce chips were cut into fine “matchsticks” (~2 mm widths) and soaked in water under vacuum to remove any trapped air. Then the matchsticks were treated with PAA (4 wt. % in water, pH=4.8 before reaction) for 45 min at 85 °C.The chemical loading of PAA was 35 g PAA to 100 g of raw materials (spruce).The reaction vessel (a plastic bottle) was gently agitated every 10 min,with no stirring required.After reaction, the treated matchsticks were drained and treated with a fresh batch of PAAsolution under the same conditions as the previous PAA treatment. In this way, multiple rounds of PAA treatment were performed until all individual fibers were liberated, which depends on the wood source and size.