Síntese interfacial de nanocompósito de matriz celulósica e polímeros condutores

Abstract

The objective of the present study is to perform the synthesis and characterization of cellulose matrix nanocomposites associated polymers (o-methoxyaniline) and poly (o-ethoxyaniline) by interfacial synthesis, as well as to characterize the materials obtained. Cellulose was obtained from the stem of the Peperomia pellucida plant that was submitted to chemical treatments such as alcoholic cleaning, mercerization and bleaching. The conductive polymers were synthesized by interfacial chemical route, using HCl as doping acid in concentrations of 1M. The structural characterization of the materials was performed using the X-Ray Diffraction (XRD) techniques, followed by the estimation of crystallinity by Peak Deconvolution Method and Structural Refinement by Le Bail Method. The thermal behavior was studied through the Thermogravimetric Analysis (TG/dTG), and the characteristic morphologies by Scanning Electron Microscopy (SEM). The results of the present research indicate that the cellulose obtained in the form of nanofibrils was thermally more stable than the original fiber, and its structure was identified as belonging to the type Iα polymorph. The conductive polymers exhibited some structural changes related to the size of the lateral grouping, such as POEA that presented unit cell higher than POMA. Both conducting polymers presented characteristic morphologies of conductive polymers. POMA/cellulose and POEA/cellulose composites presented structural changes, like a reduction in the unit cell of the conducting polymer and an increase in that related to cellulose phase when compared to the neat polymers. The growth in the crystallite size of both the phases might be result of chemicals interactions between the phases, this produced an higher crystallinity in the composite. Although the conductive polymers act as a retarder of mass loss in the composites, they are thermally less stable than pure cellulose. A preferential growth of the conductive polymers on cellulose surface fibrils was observed through the MEVs. These results shows the structural changes related to the synthesis of conductive polymers POMA and POEA as reinforcement in the composite of cellulosic matrix, as well as their influence on the thermal behavior and morphology of the composite.