Advances in sugar-based polymers: xylan and its derivatives for surface modification of pulp fibres

Xylans are one of the most common hemicellulose polysaccharides and natural polymers in plants. The utilization of xylan as a polymer has great potential for functional materials in different applications. In this chapter, different processes for the extraction of xylans from biomass are evaluated, due to their influence on the final properties of the extracted polymers such as molar mass and purity. Pressured hot water extraction (PHWE), a very common but versatile method for extracting xylans from hard wood, is described in detail. Cold caustic extraction (CCE) of xylans from bleached hard wood pulps is discussed as an alternative route for obtaining extremely pure xylan polymers. Derivatisation of the extracted xylans by incorporation of functional groups such as ethers and esters to the xylan backbone is a toolbox that allows the incorporation of a huge range of tailor-made new features for the polymer. Fibre engineering with sorption of xylans and xylan derivatives through self-assembly gives the perfect opportunity for incorporation of brand new functionalities to fibre-based products, which results in improved performance and helps to broaden the application areas for these materials.