Preparation and characterization of biocomposites based on sisal cellulose esters/cellulose: use of XPS and ToF-SIMS techniques for surface analysis

Abstract

Up to the present moment, syntheses of sisal cellulose esters were explored, as well as the preparation of films (reinforced or not with sisal cellulose) from these esters. These will be the starting materials for the study that will be developed, ie, films prepared from cellulose esters [different chain lengths and degree of substitution (DS)] solutions and biocomposites-type films prepared from mixed solutions based on esters plus sisal cellulose. The films will be characterized by techniques already under consideration, as DMTA (for evaluation of mechanical properties, in order to evaluate if the cellulose acts as a reinforcing agent) and SEM (for morphology evaluation). In addition, X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) will be used to characterize the films. Sisal cellulose beads and beads from its esters will be also prepared. Cellulose beads are spherical microparticles with a wide range of applications in various fields, such as drug delivery systems for controlled release, removal of heavy metal ions etc. These materials wil be characterized via SEM, XPS and ToF-SIMS. These two last techniques are powerful analysis tools, which provide sample depths on the order of 3-10 nm and 0.2-1 nm, respectively. The combination of these two techniques is therefore particularly appropriate: XPS technique providing semi-quantitative information on the surface elemental composition (including the inter-elements bonding) and ToF-SIMS providing a detailed surface chemical characterization. XPS and ToF-SIMS techniques will be helpful in understanding of the ester groups distribution on the surface of the films and beads, contributing to the comprehension of its dependence with the ester chain length, DS, presence of cellulose in the films, which should allow a correlation between these characteristics and other films properties, such as mechanical and barrier properties. (AU)