Scale build up, the formation of insoluble inorganic compounds on a surface, can significantly impact a variety of industrial water handling processes. Materials that form complexes with water-soluble cations have proven to be effective antiscalants. Polyacrylate is an extensively used anionic antiscalant and dispersant made by reaction of poly(acrylic acid) with sodium hydroxide. While non-toxic, polyacrylate is not biodegradable and so must be precipitated as sludge and landfilled. This learning module discusses the synthesis of biodegradable, thermal polyaspartates (TPA) as a greener replacement for polyacrylate. TPA is prepared by heating L-aspartic acid to produce polysuccinimide in high yield with only water as a byproduct. Polysuccinimide is subsequently ring opened with sodium hydroxide to give polyaspartate with alpha and beta-linkages.
The Donlar Corporation developed, manufactures, and markets TPA and received the first Presidential Green Chemistry Challenge Award in the small business category in 1996. The module includes a list of seven questions, "Notes to Instructors" and a PowerPoint presentation. Concepts described in this module can be incorporated during a discussion of polymers and polymer chemistry.
Summary prepared July 2005 by Bruce D. Allison, Department of Chemistry at Rose-Hulman Institute of Technology.
Narsavage-Heald, D. Thermal Polyaspartate as a Biodegradable Alternative to Polyacrylate and Other Currently Used Water Soluble Polymers. http://academic.scranton.edu/ faculty/ CANNM1/ polymer/ polymermodule.html (accessed June 2011).