Unraveling the effect of the hydration level on the molecular mobility of nanolayered polymeric systems

This work investigates the influence of the hydration level on the molecular mobility and glass transition dynamics of free-standing chitosan/alginate (CHT/ALG) nanolayered systems. Non-conventional dynamic mechanical analysis identified two relaxation processes assigned to the α-relaxation of the two biopolymers, respectively CHT and ALG, when immersed in water/ethanol mixtures. This phenomenon explains the shape memory properties of the multilayered systems induced by hydration, thus constituting promising smart materials that would be of paramount importance in a plethora of research fields, including in the biomedical and biotechnological fields.This work has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS. The work was also funded by FEDER through the Competitive Factors Operational Program (COMPETE) and by National funds through the Portuguese Foundation for Science and Technology (FCT) in the scope of the projects PTDC/FIS/115048/2009 and PTDC/CTM-BIO/1814/2012. S.G.C and J.M.S. gratefully acknowledge FCT for the concession of postdoctoral and doctoral grants with the reference numbers SFRH/BPD/96797/2013 and SFRH/BD/81372/2011, respectively