ICN Spring Seminar Student Profiles: Erik Johnston

I am a third year PhD candidate in the Materials Science Program here at the University of Montana.  The program is a collaborative degree between the University of Montana, Montana Tech, and Montana State University.  My graduate research is focused the use of D-glucaric acid as a versatile building block for the formation of biodegradable, renewably-sourced materials.  D-Glucaric acid is produced through the oxidation of D-glucose, which in North America is primarily sourced from corn.  Companies such as Rivertop Renewables, a green chemical manufacturer based in Missoula, MT, have found economically viable oxidation methods for the production of glucaric acid and its salts.  Current applications of glucaric acid salts are as corrosion inhibitors in the water treatment industry and as hard water sequestering agents in automatic dishwashing detergents.  My research however is focused on the use of glucaric acid as a monomer for the synthesis of polyamides through a simple condensation reaction with a wide range of diamines.
           
Polyamides produced from glucaric acid are more commonly referred to as poly(glucaramides), and have a similar structure to commercially available Nylon polymers.  These poly(glucaramides) have unique properties that are tunable through the selection of monomers used for polymerization.  Specifically the water solubility of poly(glucaramides) can be controlled through the aliphatic chain length of the diamine.  Polymers produced with shorter diamines, such as tetramethylenediamine, show more hydrophilic character and are water soluble.  When more hydrophobic diamines, such as the 6 carbon hexamethylenediamine, are used in the polymerization the resulting polymers are insoluble in water.  Through the careful selection and mixing of these diamines one can control the solubility of the resulting poly(glucaramides) and promote hydrogel formation.

Hydrogels are water-based, solid-like structures that can be over 99% water and still behave as a solid.  Jell-O® and contact lenses are two commonly known examples of hydrogels, but hydrogels can be used in a multitude of other areas such as controlled release delivery systems, tissue engineering, and in disposable diapers.  I am exploring the poly(glucaramide)-based hydrogels as materials for the controlled release of fertilizers.  Currently, a large portion of the fertilizer that is applied to crops is not utilized and is released into environment through runoff.  This leads to high concentration of nutrients in the surrounding water and results in the eutrophication of downstream water systems.  A controlled release system could alleviate some of these risks associated with fertilizing crops.  Additionally, if the delivery system is a biodegradable poly(glucaramide) hydrogel produced from corn, after the fertilizer has been delivered the material will be degraded with no further accumulation in the environment.