Marco Apostolo

Propagation velocity of the reaction front in addition polymerization systems

Traveling polymerization fronts in unstirred solutions of methylmethacrylate, methacrylic acid, or acrylamide with some free radicals initiators (through thermal decomposition) have been observed experimentally. A local heating of the initial reactant mixture, under suitable conditions, leads to a reaction front that propagates along the space coordinate with a constant velocity. In this article, a physical interpretation of this phenomenon is provided through a mathematical model that accounts for the depolimeri-zation reaction and is based on the constant pattern approach. Moreover, an approximate explicit analytic expression for the velocity of propagation of the polymerization front is proposed. The theoretical values are compared with those measured experimentally as a function of the initiator concentration for different addition polymerization systems.

Copper Plating of LiCoO2 Particles for Water Friendly Electrodes in Li-Ion Batteries

Lithium cobalt oxide (LiCoO2) is the most widesprea d used active material in conventional cathodes for l ithiumion batteries. Its structural and electrochemical p roperties have been extensively studied [1-3]. The value of LiCoO2 charge capacity, 150 mA h g-1, is one of the reasons that prompted research in seekin g for alternatives to be used at the positive electrode. Plenty of cathode materials have been studied, for example sp inel [2,4] and LiFePO4 [2,5] amongst the others. Moreove r, modification of lithium cobalt oxide properties has been achieved by coatings of the active material with di fferent materials and with various techniques [6,7]. In commercial grade lithium batteries, electrodes a re produced by mixing the active material and additive s with a polymeric binder in an organic solvent, and then applying the resulting slurry onto a metallic curre nt collector. The solvent is then removed from the ele ctrode via evaporation with an annealing treatment. The us of an organic solvent is necessary since LiCoO2 underg oes chemical decomposition in an aqueous environment [8 ].