A Fundamental Review of the Relationships between Nanotechnology and Lignocellulosic Biomass - The Nanoscience and Technology of Renewable Biomaterials - page 26

and surface properties. For example, nanocrystalline cellulose is roughly 3-5 nm in
diameter and hundreds of nanometers in length. While nanocrystalline cellulose has the
potential to be produced in extremely large volumes, the utility of the nanocrystalline
cellulose for commercially desirable products will greatly depend upon its uniformity of
size, composition, structure, and surface functionality. The properties of nanocrystalline
cellulose must not differ from one lot or batch to another. Cost-effective methodologies
must be developed to liberate, fractionate, and separate cellulosic nanomaterials into
uniform, reproducible cohorts that can be easily dispersed for fabrication of macroscale
products. Isolation of nanocrystalline cellulose and nanofibrils is an important area for
research and development because current techniques appear to be lacking. For example,
hydrolysis of wood with strong acids to liberate nanocrystalline cellulose does not appear
to be an environmentally or economically friendly process and ultrasonic disintegration
has shown only partial success. In addition, real-time, inline measurement techniques
are needed to monitor and provide reproducible control of properties such as particle
size and distribution. Predictive models of nanomaterials behavior are also needed
in order to correlate nanomaterials' properties and end-use performance requirements.
Such predictive models are critically important to cost effectively determine macroscale
properties from constitutive bulk matrix and admixed nanomaterials properties without
having to do costly and time-consuming trial and error experimentation for product
development.

1.12.3 Controlling Water/Moisture Interactions with Cellulose

This nanotechnology priority area is aimed at the very broad area of understanding and
controlling lignocellulosic/water interactions. A primary goal is to develop a substantial
knowledge base which will enable us to advantageously alter lignocellulosic/water inter-
actions to produce new and improved products and achieve more efficient and effective
processes. Because of the almost universal influence of the relationship between water
and lignocellulosics, this priority area is closely tied to many of the technology plat-
form areas goals for research, development and demonstration expressed in The Forest
Products Industry Technology Roadmap . The specific objectives in this nanotechnology
area are to (1) develop an extensive knowledge base of the interactions of water and
lignocellulosics at the nanoscale and (2) influence and modify these relationships with
the goal of producing new as well as improved existing products and processes.
Virtually all aspects of lignocellulosic-based products and the processes by which
they are made are impacted by the relationship between water and the lignocellulosic
components of the products. The response of cellulose, hemicelluloses and lignin to
moisture (both liquid and vapor) is due almost entirely to the super molecular structure
of the biopolymers and the nanoscale structures of the lignocellulosic composites that
comprise the wood fiber. Factors such as extractives content and location also play
a role. However, most of the response to moisture depends on characteristics of the
nanoscale structures in the fiber walls. Elementary nanofibrils, which have cross-section
dimensions of about 3-5 nm are composed of cellulose polymer chains arranged in
ordered (crystalline) and less ordered (amorphous) regions. The nature of these structures
greatly influence the way in which the woody plant fiber responds to moisture. Gaining
an understanding of these interactions and learning how to manipulate the structures