Comparative study of nano and macro mechanical properties of cellulose triacetate based nanocomposites by mean of quantitative nanomechanical mapping and mechanical testing

Cellulose triacetate (CTA) based nanocomposites modified with sol-gel synthesised vanadium oxide nanoparticles (V2O5) and poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO or EPE) triblock copolymer were prepared by solvent vapour annealing (SVA) method. The present investigation was mainly focused on the study of the mechanical properties of designed nanocomposites from nanoscale, employing atomic force microscopy (AFM) and quantitative nanomechanical mapping (QNM), to macroscale using a universal testing machine. AFM results showed microseparated PPO domains in V2O5-EPE/CTA nanocomposites, being the sol-gel content of the nanocomposites the factor which affected the size and structure of these domains. These microphase separation affected strongly mechanical properties at both nano- and macroscale, which was especially reflected in QNM adhesion measurement. 3V2O5-EPE/CTA nanocomposite displayed the best well-ordered nanostructuration, which improved nanoparticles dispersion and enhanced both QNM and Young's modulus. Moreover, QNM modulus images enabled to measure the modulus of each microseparated phase, presenting the modulus of V2O5 nanoparticles the higher values. On the other hand, the addition of sol-gel solution provoked a maximum increment of 41% in the Young's modulus of V2O5/CTA nanocomposites if compared with neat CTA, being this increase of 32% in the case of V2O5-EPE/CTA nanocomposites, if compared with EPE/CTA blend.