Location: Plant Polymer Research2012 Annual Report
1a. Objectives (from AD-416):
The long-term objectives of this project are to develop new technologies and knowledge to enable expanded growth of biobased materials, new market opportunities for agricultural products, and reduced environmental impact. Objective 1: Develop and characterize electroactive materials from natural polymers that enable commercially viable technologies. Objective 2: Develop and characterize stimulus-responsive starch-based materials that enable the commercially viable technologies. Objective 3: Develop cutting-edge computational tools for starch and other natural polymers using density functional theory and empirical energy approaches that enable development of new technologies.
1b. Approach (from AD-416):
Develop new biobased materials with novel properties from starch-based commodities. Novel properties include electroactive and stimuli-responsive polymeric materials. Develop molecular modeling tools for use in rational design approaches.
3. Progress Report:
Carbon black, produced using non-renewable starting materials, is often incorporated into a polymer to make the polymer more electroactive. There is a need to develop technologies using renewable materials. ARS, Plant Polymer Research scientists at the National Center for Agricultural Utilization Research in Peoria, IL, determined structure-function properties of agricultural polymers. Specifically, we studied biobased polymers as electroactive composites but the far-ranging applications could be biosensors, environmentally sensitive membranes, artificial muscles, actuators, electronic shielding, visual displays, solar materials, and components in high-energy batteries. Starch was combined with lignite (a fossilized lignocellulose from coal mines) and biochar (carbon residue from syngas production) to form electroactive composites and evaluated for surface activity and bulk conductivity. Composites were extruded using a single-screw extruder using a manual feeder. Film thicknesses ranged from 0.1-1.0 mm. Mechanical properties were measured and showed physical reinforcement of the polymer matrix. The conductivity of composites showed a 100-fold increase over the polymer matrix. Lignite, while containing substantial amounts of carbon, did not perform as well as biochar. In addition, studies with a university partner characterized exopolysaccharides using light scattering and allowed the correlation of structural components to functional properties of anticorrosive biobased materials. By reducing the damage of fungal rot on developing corn kernels, the overall yield of corn per acre can be increased. ARS, Plant Polymer Research scientists at the National Center for Agricultural Utilization Research in Peoria, IL, used computer modeling to determine the structure of large peptides (24 amino acids). This calculated data can then be used to compare with experimentally determined structures. Two techniques, were used with limited success. The molecule studied was corn chitinase peptide (ChitA) in collaboration with (Renewable Product Technology, NCAUR). ChitA is present in developing kernels of corn and is attacked by fungal rot. Determining the structure of ChitA is important to plant breeders to produce maize hybrids resistant to fungal diseases. The ability to release compounds of interest, whether these be pharmaceuticals, flavorants, pesticides or other chemicals, at the desired rate can be very beneficial. Computer modeling studies on corn starch with different structures have been performed on up to 8 sugar residues. The structure of starch formation is essential to forming products where controlled-release or protection of biologically active compounds is desirable.
1. Electroactive (polymers that respond to electricity) biobased polymer composites. ARS, Plant Polymer Research scientists at the National Center for Agricultural Utilization Research in Peoria, IL, made green polymer composites using biobased carbon materials. Carbon materials were provided by local syngas producers (biochar) or from regional coal mines (lignite). Biochar or lignite from agricultural and mining waste streams were combined with biobased polymers (corn starch, polylactic acid) to form green composites which resulted in reinforced thin films and also increased the conductivity to functional levels. Electroactive composites could be used as environmentally sensitive membranes for active food packaging or controlled release of biologically active compounds in field applications. This technology also contributes to the sustainability of local energy production using renewable resources.
2. Structures of important enzymes. ARS, Plant Polymer Research scientists at the National Center for Agricultural Utilization Research in Peoria, IL, determined structures of important enzymes that affect the ability of corn to protect itself. They used sophisticated computer modeling tools to predict the structure for large proteins. The protein studied was corn chitinase peptide (ChitA) which is an important protein in the corn that is attacked by a fungal rot disease. The data were used to determine the structure of ChitA as it is bound and cleaved. By understanding it is structure, plant breeders may be able to introduce ChitA variants into the corn that will be resistant to fungal diseases.
3. Modeling inclusion complexes of starch. ARS, Plant Polymer Research scientists at the National Center for Agricultural Utilization Research in Peoria, IL, examined a unique structure of starch. Starch is the main storage polymer that plants, like corn, use for energy. Starch can also be used to deliver valuable compounds that have utility in agricultural, pharmaceutical, and food systems. The structure of starch was studied using computer techniques. By learning more about the structure of starch, compounds can be designed that can fit inside of the starch (a starch inclusion complex) and be released from the starch to deliver valued properties.