Tools for the Characterization of Biomass at the Nanometer Scale - The Nanoscience and Technology of Renewable Biomaterials - page 61

3

Tools for the Characterization
of Biomass at the Nanometer Scale

James F. Beecher, Christopher G. Hunt and J.Y. Zhu

3.1 Introduction

To take advantage of nanoscale features in plant cell walls and create our own nanos-
tructures based on plant biomass, we must make reliable measurements at the nanoscale.
Although nanoscale measurement methods have expanded in recent years, not all these
techniques are useful for soft, hydrophilic, nonconducting biomass specimens. Here we
discuss those methods with the potential to be particularly useful in studying nanoscale
properties of plant biomass.
In contrast to most engineering materials, plant biomass structure changes with water
availability. Water swells biomass, creating pores that transport enzymes and reagents
into and out of the cell wall during processing. Therefore we begin with a description
of basic interactions of water and biomass. Nanoscale accessibility and reactivity of the
cell wall are often critical to bioprocessing, so we discuss several methods of evaluating
these properties. This chapter also describes methods to measure cellulose crystallinity,
because crystallinity affects properties and crystallites are an interesting material in them-
selves. Finally the chapter reviews microscopic and spectroscopic methods useful for
the study of biomass at the nanoscale.

3.2 Water in Biomass

Water has a profound effect on the nanoscale structure of plant cell walls. Nanoscale
pores in wet spruce wood, a representative biomass, commonly contain 0.3 g water