polyaspartic acid sodium salt
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
The polymerization reaction is an example of a step-growth polymerization to a polyamide and in one practical procedure aspartic acid is simply heated to 180 °C resulting in water release and the formation of a poly(succinimide). In the subsequent step, this polymer is reacted with sodium hydroxide in water, which hydrolyzes one of the two amide bonds of the succinimide ring to form a sodium carboxylate. The remaining amide bond is thus the linkage between successive aspartate units. Each aspartate unit is identified as α or β according to which carbonyl of it is part of the polymer chain. The α form has one carbon in the backbone in addition to the carbonyl itself (and a two-carbon sidechain) whereas the β form has two carbons in the backbone in addition to the carbonyl itself (and a one-carbon sidechain). This reaction gives a sodium poly(aspartate) copolymer composed of approximately 30% α-linkages and 70% β-linkages.
This material can be synthesized in an environmentally friendly way and is biodegradeable, thus it is a green alternative to several materials such as sodium polyacrylate used in disposable diapers and agriculture.
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- "Presidential Green Chemistry Challenge Awards: 1996 Small Business Award: Donlar Corporation (now NanoChem Solutions, Inc.): Production and Use of Thermal Polyaspartic Acid". US Environmental Protection Agency.
- Low, K. C.; Wheeler, A. P.; Koskan, L. P. (1996). Commercial poly(aspartic acid) and Its Uses. Advances in Chemistry Series 248. Washington, D.C.: American Chemical Society.
- Thombre, S.M.; Sarwade, B.D. (2005). "Synthesis and Biodegradability of Polyaspartic Acid: A Critical Review" (PDF). Journal of Macromolecular Science, Part A 42 (9): 1299–1315. doi:10.1080/10601320500189604.
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