Preparation Of Poly(Carbonyl Urea) Oligomer (PCUO) And Its Novel Slow-released Liquid Fertilizer With Multi-nutrient

In this paper, we report the facile synthesis of a novel slow-release fertilizerpoly（carbonyl urea） oligomer （PCUO） with nitrogen and carbon nutrients, which was a“designed”molecule synthesized from dicarbonic ester and urea at optimized conditions. Theproducts we prepared have slow-release property depending on the average polymerizationdegree, and especially, it may be completely degraded into ammonia and carbon dioxide bychemical and biological degradation in soils. In addition, a novel slow-released liquidfertilizer with multi-nutrient was further obtained from PCUO and potassium dihydrogenphosphate （KDP） by melt polycondensation. The slow-released property and the mass ratio ofthe nutrients can also be controlled by the average degree of polymerization n and m.Consequently, it could be used as various special fertilizer applied to different kinds of crops.A complete study of PCUO was carried out by three steps. Triuret was first successfullysynthesized by the reaction of urea with dimethyl carbonate （DMC） under mild conditions inthe presence of potassium methoxide as a catalyst. And PLUO was then prepared by thecondensation polymerization of urea and dipropyl carbonate （DPrC） at normal pressure.Furthermore, PCUO could also be prepared by the ammonolysis reaction of urea and DMC（dimethyl carbonate） in autoclave with carbon dioxide filled. The best yield can be 88.3%under the optimization condition. The average degree of the polymerization was confirmed 11by¹³C-NMR, FT-IR and elemental analysis.The slow-released liquid fertilizer with multi-nutrient was further synthesized from PCUOand KDP by melt polymerization. The effect of the molar ratio of PCUO to KDP, the reactiontime and the reaction temperature on the yields as well as viscosity was further investigated indetail. The product as a liquid soluble fertilizer was particularly suitable for the drip irrigation and furrow irrigation of vegetable greenhouse, which may be gradually degraded into thesmaller molecular nutrition by degradation of the water and microorganism.