%0 Journal Article %T Effect of Cellulose Nanofibers’ Structure and Incorporation Route in Waterborne Polyurethane–Urea Based Nanocomposite Inks %+ Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM) %A Larraza, Izaskun %A Vadillo, Julen %A Calvo-Correas, Tamara %A Tejado, Alvaro %A Martin, Loli %A Arbelaiz, Aitor %A Eceiza, Arantxa %< avec comité de lecture %@ 2073-4360 %J Polymers %I MDPI %V 14 %N 21 %P 4516 %8 2022-10-25 %D 2022 %R 10.3390/polym14214516 %K waterborne polyurethane-urea 3D printing cold extrusion cellulose nanofibers bioinks %K waterborne polyurethane-urea %K 3D printing %K cold extrusion %K cellulose nanofibers %K bioinks %Z Chemical Sciences/Material chemistry %Z Chemical Sciences/Polymers %Z Chemical Sciences/Theoretical and/or physical chemistry %Z Chemical Sciences/Analytical chemistryJournal articles %X In order to continue the development of inks valid for cold extrusion 3D printing, waterborne, polyurethane-urea (WBPUU) based inks with cellulose nanofibers (CNF), as a rheological modulator, were prepared by two incorporation methods, ex situ and in situ, in which the CNF were added after and during the synthesis process, respectively. Moreover, in order to improve the affinity of the reinforcement with the matrix, modified CNF was also employed. In the ex situ preparation, interactions between CNFs and water prevail over interactions between CNFs and WBPUU nanoparticles, resulting in strong gel-like structures. On the other hand, in situ addition allows the proximity of WBPUU particles and CNF, favoring interactions between both components and allowing the formation of chemical bonds. The fewer amount of CNF/water interactions present in the in situ formulations translates into weaker gel-like structures, with poorer rheological behavior for inks for 3D printing. Stronger gel-like behavior translated into 3D-printed parts with higher precision. However, the direct interactions present between the cellulose and the polyurethane-urea molecules in the in situ preparations, and more so in materials reinforced with carboxylated CNF, result in stronger mechanical properties of the final 3D parts. %G English %2 https://univ-pau.hal.science/hal-03879805/document %2 https://univ-pau.hal.science/hal-03879805/file/polymers-14-04516-v2.pdf %L hal-03879805 %U https://univ-pau.hal.science/hal-03879805 %~ CNRS %~ UNIV-PAU %~ IPREM %~ INC-CNRS %~ UPPA-OA %~ TEST2-HALCNRS