Comomer compositions for production of imide-containing polyamino acids

#The present invention includes monomer compositions containing aspartic acid and other comonomers, such as monosodium aspartate, and methods for their production. The monomer compositions can be polymerized, particularly by thermal polymerization, to obtain useful and novel imide-containing polyamino acids, i.e., copolymers containing polymerized aspartic acid or aspartate units and succinimide units. Thus, the invention is also directed to the resulting polymeric materials, their methods of production, and their uses as described herein. Uses of the imide-containing polyamino acids include, for example, dispersants in detergents and cleansers, water-treatment chemicals as anti-scalants and corrosion inhibitors, personal-care additives for softening and moisturizing, and many others.

#Aspartic acid has been produced commercially since the 1980's via immobilized enzyme methods. The aspartic acid so produced mainly has been used as a component of the synthetic sweetener, N-aspartyl phenylalanine methyl ester (ASPARTAME®).

#In a typical production pathway, a solution of ammonium maleate is converted to fumarate via action of an immobilized enzyme, maleate isomerase, by continuous flow over an immobilized enzyme bed. Next, the solution of ammonium fumarate is treated also by continuous flow of the solution over a bed of the immobilized enzyme, aspartase. A relatively concentrated solution of ammonium aspartate is produced, which then is treated with an acid, for example nitric acid, to precipitate aspartic acid. After drying, the resultant product of the process is powdered or crystalline L-aspartic acid. Prior art that exemplifies this production pathway includes U.S. Pat. No. 4,560,653 to Sherwin and Blouin (1985), U.S. Pat. No. 5,541,090 to Sakano et al. (1996), and U.S. Pat. No. 5,741,681 to Kato et al. (1998).

#Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings wherein the figures depict the following:

#FIG. 1. Infrared spectrum of polysuccinimide. Note the characteristic imide peak at ˜1716 cm−1. This polysuccinimide was produced via thermal polymerization of aspartic acid at 220° C. for 8 hours, yielding a completely water-insoluble polymer of Mw˜3000. Note the evidence of some degree of ring-opened structure as suggested by the amide peak at 1630 cm−1, which is thought to signify branch points, each of which would terminate in carboxylic groups. The carboxylic groups are signaled by the peak at 1400 cm−1.

#FIG. 2. Infrared spectrum of sodium polyaspartate, prepared by mild alkaline hydrolysis (succinimide ring-opening) of the polysuccinimide of FIG. 1. This polyaspartate was 11% by weight Na+, determined by flame photometry. Note the characteristic amide doublet at ˜1600 and 1650 cm−1, as well as the prominent carboxylate signal at ˜1400 cm−1.

#The entire disclosure of all applications, patents and publications, cited above and below, are hereby incorporated by reference.

#In the foregoing and in the following examples, all temperatures are set forth uncorrected in degrees Celsius.

#Infrared Spectroscopy