Location: Plant Polymer Research2013 Annual Report
1a. Objectives (from AD-416):
The long-term objective of this project is to develop processes to enhance the conversion of cereal crops and residues into value added polymers, demonstrate the useful properties and applications of these biobased materials, reduce dependence on petroleum and increase utilization of environmentally friendly renewable resources. Objective 1: Develop technologies that enable commercially viable products composed of lipid and amylose or modified starch complexes with novel micro- and nano-sized spherulitic morphologies; Objective 2: Develop reactive extrusion-based technologies that enable commercially viable graft co-polymers from starches and lignocellulosics; Objective 3: Develop novel chemical and thermal processes that enable the commercially viable production of derivatives of starches, lignins, and lignocellulosics; Objective 4: Develop novel biocatalytic processes to produce commercially viable derivatives of starches, lignins, and/or lignocellulosics.
1b. Approach (from AD-416):
New biobased products and sustainable processing technologies are needed to replace industrial and consumer products made from petroleum based feedstocks. This project focuses on making polymeric materials with a variety of useful applications from starch and associated low cost coproducts of corn processing and harvesting. In order to accomplish this, modified biopolymers with new or improved properties need to be prepared and processing technologies which are more efficient, i.e. use safer or less solvent, are faster, have more complete reaction and fewer byproducts need to be developed. Specific objectives for this project include: 1) prepare novel spherulitic starch-polymer composites via jet-cooking; 2) prepare starch graft copolymers with controlled structure by reactive extrusion and evaluate applications; 3) prepare modified starches, celluloses and lignins with novel structures via processing with ionic liquids, microwaves and autoclave heating; and 4) prepare new starch and lignin graft copolymers as well as polyglutamic acid and polyhydroxyalkanoates by enzymatic and microbial catalysis. Overall, this research will lead to biobased polymer products which will have new or improved properties, have lower cost, are more environmentally friendly and thus will be more acceptable to consumer markets.
3. Progress Report:
A detailed study of the acetylation of starch in four ionic liquids was conducted. All four ionic liquids were found to be acceptable with respect to the acetylation reaction. An advantage to this route is that pyridine was found to be unnecessary for the reaction to proceed. It was also discovered that starch could readily react with two identified anhydrides in ionic liquids to give the corresponding derivatives. The products were anionic and might be useful as anionic polysaccharides. Amylose inclusion complexes were prepared by jet-cooking mixtures of high amylose corn starch and 1-hexadecylamine (HDA) or its hydrochloric acid (HC1) salt. Water insoluble spherulites were formed from the amylose-HDA complex and were similar to those prepared from palmitic acid. Aqueous solutions of a cationic amylose complex were obtained when the HCl salt of HDA was used. These starch-HDA salts functioned as flocculating agents, suggesting their use in water purification and as retention aids in papermaking. Starch-polyglutamic acid (PGA) graft copolymers have been produced. PGA was prepared from low cost corn condensed distillers solubles and distillers dry grains and solubles. The impact of pH and temperature on production and structure of PGA was evaluated. The rheological and flocculation properties as well as water solubility/absorption index of the starch-PGA graft are being conducted. The study of starch-poly(methyl acrylate) graft copolymers prepared from jet-cooked aqueous dispersions of amylose-oleic acid spherulites has been expanded to include aqueous spherulite dispersions in which un-complexed, water soluble amylopectin was removed by water extraction. Spherulite-reinforced plastics with good tensile properties were obtained from these graft copolymers by extrusion processing. Nano-particles of lignin were prepared using a high temperature and pressure homogenizer. Impact of temperature, pressure, and time on lignin particles were tested and will be evaluated using transmitted electronic microscopy, scanning electronic microscopy, and light scattering. The viscoelastic properties of starch-polyacrylamide graft co-polymers prepared from water (few long branches) and dimethyl sulfoxide (many short branches) was evaluated. These co-polymers can swell water at room temperature and form gels. These two starch graft co-polymers exhibited different behaviors under shear. These two different starch graft copolymers can be good candidates for wound-healing gel, drug delivery material, and cosmetic cream according to their different properties. It was determined that microwave processing could replace jet cooking to prepare starch-palmitic acid spherulites in similar yield. The steam jet cooking process is more robust, however if only small quantities of spherulites are needed, then microwave processing has value.