Hydrogels: An Effective Tool to Improve Nitrogen Use Efficiency in Crops

Hydrogels are hydrophilic polymeric materials with three-dimensional(3D) network structures physic and/or chemically crosslinked. They can absorb large amounts of water or aqueous solutions for a short period of time. When the hydrogel is loaded with a drug and meets an aqueous medium, the water penetrates the system and dissolves the drug. To improve the nitrogen use efficiency by plants, controlled release fertilizers are developed with hydrogels as matrices. In particular, biodegradable polymers such as starch, xanthan, chitosan, cellulose derivatives, pectin and their mixtures have been essayed to avoid residues in soils. In addition, the superabsorbent capacity of the hydrogels improves the retention of fertilizers in the soil, reduces water losses through evaporation and decreases the frequency of irrigation.In this chapter, the behavior of different hydrogels to improve the availability of nitrogen by the plants during their crop cycle will be reviewed.Fil: Melaj, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Giménez, Rocío Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentin

Blue Light Sensitive Dyes for Various Photopolymerization Reactions: Naphthalimide and Naphthalic Anhydride Derivatives

International audienceNovel naphthalimide derivatives (or naphthalic anhydride derivatives) have been prepared and combined with an iodonium salt, Nvinylcarbazole, amines or 2,4,6-tris(trichloromethyl)-1,3,5-triazine to produce radicals and cations upon exposure to low intensity blue lights (e.g., a household blue LED bulb). The photochemical mechanisms are studied by electron spin resonance spin trapping, fluorescence, cyclic voltammetry, laser flash photolysis, and steady state photolysis techniques. The naphthalimide derivatives (ND4) or the naphthalic anhydride derivative (ND10) based photoinitiating systems are particularly efficient for cationic, radical and thiol− ene photopolymerizations; the synthesis of interpenetrated polymer networks IPNs can also be easily carried out. Compared to camphorquinone/amine or camphorquinone/iodonium salt, the new proposed combinations appear as highly versatile and high performance visible light photoinitiating systems. Some of these photoinitiating systems can also be used for UV LED irradiations (e.g., 365, 385, or 395 nm)