Differences in surface chemistry of regenerated lignocellulose fibers determined by chemically sensitive scanning probe microscopy

Abstract

Tuning the composition of regenerated lignocellulosic fibers in the production process enables targeting of specific material properties. In composite materials, such properties could be manipulated by controlled heterogeneous distribution of chemical components of regenerated fibers. This attribute requires a visualization method to show their inherent chemical characteristics. We compared complementary microscopic techniques to analyze the surface chemistry of four differently tuned regenerated lignocellulosic fibers. Adhesion properties were visualized with chemical force microscopy and showed contrasts towards hydrophilic and hydrophobic atomic force microscopy tips. Fibers containing xylan showed heterogeneous adhesion properties within the fiber structure towards hydrophilic tips. Additionally, peak force infrared microscopy mapped spectroscopic contrasts with nanometer resolution and provided point infrared spectra, which were consistent to classical infrared microscopy data. With this setup, infrared signals with a spatial resolution below 20 nm reveal chemical gradients in specific fiber types.