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Nanocelluloses (NC) increase mechanical and barrier paper properties allowing the use of paper in applications actually covered by other materials. Despite the exponential increase of information, NC have not been fully implemented in papermaking yet, due to the challenges of using NC. This paper provides a review of the main new findings and emerging possibilities in this field by focusing mainly on: (i) Decoupling the effects of NC on wet-end and paper properties by using synergies with retention aids, chemical modification, or filler preflocculation; (ii) challenges and solutions related to the incorporation of NC in the pulp suspension and its effects on barrier properties; and (iii) characterization needs of NC at an industrial scale. The paper also includes the market perspectives. It is concluded that to solve these challenges specific solutions are required for each paper product and process, being the wet-end optimization the key to decouple NC effects on drainage and paper properties. Furthermore, the effect of NC on recyclability must also be taken into account to reach a compromise solution. This review helps readers find upscale options for using NC in papermaking and identify further research needs within this field., Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Depto. de Ingeniería Química y de Materiales, Fac. de Ciencias Químicas, TRUE, pub

Cellulose and chitin are the most abundant polymeric materials in nature, capable of replacing conventional synthetic polymers. From them, cellulose nano/microfibers (CNFs/CMFs) and chitosan are obtained. Both polymers have been used separately in graft copolymerization but there are not many studies on the use of cellulose and chitosan together as copolymers and the reaction mechanism is unknown. In this work, the reaction mechanism to produce nano/microcellulose-graft-chitosan polymer has been studied. Recycled cellulose pulp was used, with and without a 2,2,6,6-tetramethylpiperidin-1-oxyl-radical (TEMPO)-mediated oxidation pretreatment, to produce CNFs and CMFs, respectively. For chitosan, a low-molecular weight product dissolved in an acetic acid solution was prepared. Grafted polymers were synthesized using a microwave digester. Results showed that TEMPO-mediated oxidation as the cellulose pretreatment is a key factor to obtain the grafted polymer CNF-g-CH. A reaction mechanism has been proposed where the amino group of chitosan attacks the carboxylic group of oxidized cellulose, since non-oxidized CMFs do not achieve the desired grafting. 13C NMR spectra, elemental analysis and SEM images validated the proposed mechanism. Finally, CNF-g-CH was used as a promising material to remove water-based inks and dyes from wastewater., Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid/Banco de Santander, Depto. de Ingeniería Química y de Materiales, Fac. de Ciencias Químicas, TRUE, pub