POLYANILINE MODIFIED CELLULOSE NANOFIBRILS AS REINFORCEMENT OF A SMART POLYURETHANE

M. L. AUAD; T. RICHARDSON; W.J. ORTS; E.S. MEDEIROS; L.H.C. MATTOSO; M. .A. MOSIEWICKI; N. E. MARCOVICH,; M.I. ARANGUREN

POLYMER INTERNATIONAL

JOHN WILEY & SONS LTD

Lugar: Malden, MA; Año: 2011 vol. 60 p. 743 - 750

0959-8103

Segmented polyurethanes exhibiting shape memory properties (SMPs) were modified by the addition of polyaniline-coated cellulose nanofibrils (PANI-CNF). The two-phase structure of the polymer is responsible for the material’s ability to “remember” and autonomously recover its original shape after being deformed, in response to an external thermal stimulus. Polyaniline (PANI) was grown on the surface of the CNF via in situ polymerization. Modified nanocrystals were added to the segmented polyurethane in concentrations ranging from 0-15 wt%. The changes in the material properties associated with the percolation of the coated fibrils appeared at higher concentrations than previously observed for non-modified CNF, which suggests that fibril agglomeration is occurring due to the PANI coating. The shape memory behavior of the composites was maintained at about the same level of the unfilled PU, only up to 4 wt.% of fibrils. At higher concentrations, the rigidity of the nanofibrils as well as their interaction with the hard segment phase and the increasing difficulty of dispersing them in the polymer collaborate to produce early breakage of the specimens when stretched at temperatures above the melting of the soft segments.