h i g h l i g h t sDicyandiamide (DCD) was encapsulated in glyoxal-crosslinked chitosan hydrogel beads. Chitosan delayed the release of nitrification inhibitor DCD in water and soil. DCD release was controlled by glyoxal polymerisation inside chitosan. The higher glyoxal polymerisation the more delayed DCD release in water or in soil. The higher glyoxal polymerisation the less DCD encapsulated in the beads. a r t i c l e i n f o b s t r a c tUsing chemical inhibitors to reduce soil nitrification decreases emissions of environmental damaging nitrate and nitrous oxide and improves nitrogen use efficiency in agricultural systems. The efficacy of nitrification inhibitors such as dicyandiamide (DCD) is limited in soil due to biodegradation. This study investigated if the persistence of DCD could be sustained in soil by slow release from a chitosan hydrogel. DCD was encapsulated in glyoxal-crosslinked chitosan beads where excess glyoxal was (i) partly removed (C beads) or (ii) allowed to dry (CG beads). The beads were tested in water and in soil. The beads contained two fractions of DCD: one which was quickly released in water, and one which was not. A large DCD fraction within C beads was readily available: 84% of total DCD bead content was released after 9 h immersion in water, while between 74% and 98% was released after 7 d in soil under low to high moisture conditions. A lower percentage of encapsulated DCD was readily released from CG beads: 19% after 9 h in water, and 33% after 7 d in soil under high rainfall conditions. Kinetic analysis indicated that the release in water occurred by quasi-Fickian diffusion. The results also suggest that DCD release was controlled by bead erosion and the leaching of glyoxal derivatives, predominantly a glyoxal-DCD adduct whose release was positively correlated with that of DCD (R 2 = 0.99, p 6 0.0001). Therefore, novel chitosan/glyoxal composite beads show a promising slow-release potential in soil for agrochemicals like DCD.

a b s t r a c t a r t i c l e i n f oIn this paper the first synthesis of poly[N-(2-cyanoethyl)pyrrole] (PPyEtCN) in a nanowire morphology is reported. The method employed is a facile, one step electrochemical growth, which does not require the use of any templates or surfactants. Using optimised conditions the nanowires nucleate to give a homogeneous film across the electrode surface, with lengths of approximately 2 μm and diameters of approximately 150 nm. Structural information on the nanowires was obtained using vibrational spectroscopy. Evidence is presented to support an instantaneous 3-D nucleation and growth mechanism for the nanowires.

ABSTRACT:We outline an electrodeposition procedure from an emulsion to fabricate novel vertically aligned open and closed-pore microstructures of poly(N-(2-cyanoethyl)-pyrrole) (PPyEtCN) at an electrode surface. Adsorbed toluene droplets were employed as soft templates to direct polymer growth. The microstructures developed only in the presence of both ClO 4 − and H 2 PO 4 − doping ions due to a slower rate of polymer propagation in this electrolyte. Two sonication methods (probe and bath) were used to form the emulsion, producing significantly different microstructure morphologies. Control over microtube diameter can be achieved by simply altering the emulsion sonication time or the amount of toluene added to form the emulsion. Electrochemical characterization indicated the PPyEtCN microtube morphology had an increased electrochemical response compared to its bulk counterpart. TEM analysis of individual closed-pore microtubes identified a hollow interior at the base within which the toluene droplet was encapsulated. This cavity may be used to entrap other compounds making these materials useful in a range of applications. The methodology was also applied to form microstructures of poly(3,4-ethylenedioxythiophene) and polypyrrole.

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