Anionic polymers composed of dicarboxylic acids and uses thereof

#1. Field of the Invention

#The present invention is broadly concerned with novel substantially biodegradable and substantially water soluble anionic polymers and derivatives thereof which have significant utility in agricultural applications, especially plant nutrition and related areas. More particularly, the invention is concerned with such polymers, as well as methods of synthesis and use thereof, wherein the preferred polymers have significant levels of anionic groups. The most preferred polymers of the invention include recurring polymeric subunits made up of dicarboxylic (e.g., maleic acid or anhydride, itaconic acid or anhydride, and other derivatives thereof monomers. The polymers may be applied directly to the ground adjacent growing plants, complexed onto ions, applied directly to seeds, and/or mixed with or coated with phosphate-based fertilizers to provide improved plant nutrition products.

#2. Description of the Prior Art

#FIG. 1 is a graph illustrating the percentage of nitrogen and ammonia lost from untreated urea over a sixteen day testing period; and

#FIG. 2 is a graph illustrating the percentage of nitrogen and ammonia lost over a sixteen day testing period from urea coated with polymer.

#The following examples set forth techniques for the synthesis of polymers in accordance with the invention, and various uses thereof. It is to be understood that these examples are provided by way of illustration only and nothing therein should be taken as a limitation upon the overall scope of the invention.

#Acetone (803 g), maleic anhydride (140 g), itaconic acid (185 g) and benzoyl peroxide (11 g) were stirred together under inert gas in a reactor. The reactor provided included a suitably sized cylindrical jacketed glass reactor with mechanical agitator, a contents temperature measurement device in contact with the contents of the reactor, an inert gas inlet, and a removable reflux condenser. This mixture was heated by circulating heated oil in the reactor jacket and stirred vigorously at an internal temperature of about 65-70° C. This reaction was carried out over a period of about 5 hours. At this point, the contents of the reaction vessel were poured into 300 g water with vigorous mixing. This gave a clear solution. The solution was subjected to distillation at reduced pressure to drive off excess solvent and water. After sufficient solvent and water have been removed, the solid product of the reaction precipitates from the concentrated solution, and is recovered. The solids are subsequently dried in vacua. A schematic representation of this reaction is shown below. 4

#This reaction was carried out in equipment similar to that used in Example 1 above. The following procedure was followed: 847 g purified water was placed into the reactor. Next, 172 g itaconic acid and 130 g maleic anhydride were added with vigorous stirring. This mixture was heated to about 85-90° C., at which temperature this mixture exists as a clear solution. When the mixture reached the desired temperature, 15 g of potassium persulfate was added to the solution. The reaction mixture was allowed to stir for 3 hours, and a second portion of persulfate, equal to the first, was added, and allowed to react for a further 3 hours. Product was isolated in the same manner as described for Example 1. A schematic representation of this reaction is shown below 5