Defence of doctoral thesis: Antonia von Schreeb – Cellulose Accessibility and Reactivity after Cold-Alkali Swelling

Abstract:

Increasing cellulose accessibility and reactivity can expand its use beyond paper products, facilitating the development of high‑performance derivatives and regenerated cellulose, as well as efficient pathways for degrading cellulose to glucose. Structurally, cellulose consists of β‑1,4‑linked D‑glucopyranoside units, each of which contains three available hydroxyl groups. However, these hydroxyl groups are not fully accessible due to cellulose’s crystalline structure. This limits reactivity, which is a key parameter not only for derivatization but also for regeneration and efficient degradation. Swelling or partial dissolution of cellulose in sodium hydroxide followed by reprecipitation has been shown to disrupt the ordered structure and increase the exposure of reactive sites. Yet the swollen material retains large amounts of water, and upon drying, it is susceptible to hornification, which reduces its ability to reswell and lowers its reactivity. This thesis explores a cold‑alkali swelling method designed to increase the reactivity across a wide range of feedstocks. A proof-of-concept with microcrystalline cellulose established strategies to mitigate hornification while preserving the swollen structure after drying. The method was then applied to paper‑grade pulps and recycled textile waste, demonstrating that these lower‑grade materials can be upcycled into more reactive cellulose suitable for derivatization, regeneration, and cellulose degradation.

https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-380534