AC electric field-assisted assembly and alignment of cellulose nanocrystals

In this article, we describe an efficient physical electric-field-assisted method to study self-assembly and orientation of cellulose nanocrystals. When applying an alternating voltage to a cellulose nanocrystals suspension deposited onto a thin gap of coplanar lithographically patterned metallic electrodes, a highly homogeneous orientation of cellulose nanocrystals is obtained. Parameters such as strength and frequency of the applied electric field and cellulose nanocrystals aspect ratios were studied to determine how they affect cellulose nanocrystals assembly and orientation. The prepared films were analyzed by atomic force microscopy, and the results suggest that the alignment of cellulose nanocrystals generated films is greatly influenced by the frequency and the strength of the applied electric field. The orientation of cellulose nanocrystals becomes more homogeneous with increasing electric field higher than 2000 V/cm with a frequency ranging between 10(4) and 10(6) Hz. (C) 2008 Wiley Periodicals, Inc.