Using a neutron beam to study nanocrystals, researchers have provided new information about hydrogen bonds that connect the building blocks of cellulose, the main molecule in cotton fibers and most other plant cell walls.



The study was coauthored by Agricultural Research Service (ARS) scientists with lead collaborators from Los Alamos National Laboratory in New Mexico and Joseph Fourier University in Grenoble, France.



The study, published in Biomacromolecules, brings researchers closer to completely describing the structure of cellulose. That structure will provide a greater understanding of the chemical and physical properties of cotton. Researchers have been studying the molecular structure of cellulose for more than a century.



To understand how cellulose changes when it is exposed to enzymes, water or chemical treatments, researchers need to learn more about its hydrogen bonding system. Certain enzymes, for example, are used to break down cellulose for use as biofuel, while others are used to treat textiles, such as stonewashing of blue jeans.



ARS chemist Alfred French and support scientist Glenn Johnson, both with the ARS Cotton Structure and Quality Research Unit in New Orleans, La., worked with computer-based molecular models, and the cooperators worked with neutron equipment. They looked at the bonds at both room temperature and at temperatures so cold that atoms almost stop moving -- about 430 degrees below zero Fahrenheit.



The researchers sought to discover whether the hydrogen atoms continuously transition or whether they remain in a fixed location. They detected only static hydrogen atoms at both temperatures. That suggests there is generally a well-ordered network of hydrogen bonds, and that there is also a different network that occurs on surfaces of the nanocrystals and in regions of defects.



Knowing more about how cotton crystals interact with neighboring molecules and their intramolecular electronic energy could eventually lead to a better understanding of defects or weaknesses at the molecular level. That better understanding could lead to improvements in permanent press and antimicrobial finishes for consumer products.



SOURCE: USDA.