Polyaniline‐modified cellulose nanofibrils as reinforcement of a smart polyurethane

Abstract

Segmented polyurethanes exhibiting shape memory properties were modified by the addition of polyaniline (PANI)-coated cellulose nanofibrils (CNFs). 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. PANI was grown on the surface of the CNFs via in situ polymerization. Modified nanocrystals were added to the segmented polyurethane in concentrations ranging from 0 to 15 wt%. The changes in the material properties associated with the percolation of the coated fibrils appear at higher concentrations than previously observed for non-modified CNFs, which suggests that fibril agglomeration is occurring due to the PANI coating. The shape memory behavior of the composites is maintained at about the same level as that of the unfilled polyurethane 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 point of the soft segments.

Transport performance in novel elastomer nanocomposites: Mechanism, design and control

“…The electrical resistivity of the SiR nanocomposites containing nickel-coated graphite exhibited high resistance to thermo-oxidative aging and salt spraying [62]. Polypyrrole and polyaniline could be coated onto the surface of cellulose nanofibrils by in situ polymerization of aniline and pyrrole [63,64]. The coated cellulose nanofibrils efficiently improved the electrical conductivity of rubber nanocomposites.…”

Effect of surface-grafted cellulose nanocrystals on the thermal and mechanical properties of PLLA based nanocomposites

“…For example, functional sites from a reaction of 2-bromoisobutyrylbromide on the surface of nanocrystals initiated the polymerization of styrene by atom transfer radical polymerization (ATRP) [13]. The "grafting to" strategy has also been used to graft poly(N-isopropylacrylamide) [14], polyaniline [15], poly(acrylic acid) [16] and poly(ethylene oxide) [17]. Poly(ε-caprolactone) has been grafted onto cellulose nanocrystals by the ring opening polymerization (ROP) of monomer using citric acid as a catalyst [18][19][20].…”

Nanocellulose and Its Application for Shape-Memory Materials

“…NC/SMP nanocomposites obtained by incorporating polyaniline-grafted CNCs SMPU, with a content of 4-10 wt%, exhibited conductivity-induced shape-memory effects. They also showed a stepwise change in thermal, rheological, and electrical properties, the maintenance of shape responsiveness of the nanocomposites [7].…”