Microstructural characterization of a natural/synthetic hybrid material by means of PALS and SAXS

J. AMALVY; C. MACCHI; P.S. ANBINDER; A. SOMOZA

Campinas

Encuentro; 26th RAU - Annual Users Meeting LNLS/CPEM; 2016

LNLS/CPEM

Chitosan is a biopolymer which offer great potentiality as packaging material, due to its inherent antimicrobial activity, non-toxicity and biodegradability [1,2]. Chemical modification of chitosan, specially grafting with different polymers is an important topic in the production of bio-based materials with enhanced properties. In the present study, two chitosan with different deacetylation degree (DD%) and molecular weight were grafted with different proportions of n-butyl acrylate, in a surfactant-free emulsion system. Stable dispersions with high grafting efficiency were obtained and the microstructure of the dispersions and casted films was analyzed by small angle x-ray scattering (SAXS) and positron annihilation lifetime spectroscopy (PALS). Results were studied and compared taking into account the DD%, molecular weight and grafting ratio.A core-shell structure was obtained on grafted samples dispersions and, on the other hand, a rupture of the typical rigid rod-structure of the polysaccharides was evidenced in hybrid films. Grafted polybutylacrylate chains break specific interactions in chitosan matrix, increasing the free nanoholevolume and their fraction. Differences in DD% and molecular weight in pristine chitosan play an important role in grafted samples microstructure because of the number and distribution of graft sites.