By an oxidative-coupling copolymerization with coumarin, the oxidation potential of polytriphenylamine was improved to 3.75V from 3.60V. The copolymer exhibited excellent electrochemical activity in redox cycling. The separator used in the experiment was prepared by roll pressing the copolymer powder with 30% (wt.) polytetrafluoroethylene into a ∼80μm thick sheet, which was incorporated into a LiFePO4–Li cell. Tests showed that when the cell was overcharged to 3.789V, the copolymer separator was oxidized and became electronically conducting, which caused short circuit formation and prevented the organic electrolyte from being oxidized. Although the cell was overcharged at 0.3C for 5h, the voltage was stable at 3.789V. When discharged, the cell released all its capacity at normal charge. The cell was overcharged seven times with identical results obtained for each cycle. Overcharging at different rates demonstrated that the separator could exhibit reversible, self-activating protection for LiFePO4-based batteries, even at 1.3mA/cm2 (3.2C to the cell).

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

In principle, it is possible to exercise control over the molecular weight distribution (MWD) of the polymers produced from living polymerisation processes in flow reactors through the control of reactant feeds in a predetermined fashion. Some of the factors that influence the extent to which control can be achieved with feed perturbations to a single stage continuous flow stirred tank (CSTR) reactor have been reported previously. Here, attention is given to the problem of establishing inverse process models as a first step towards a fully automatic control strategy for the synthesis of polymers with pre-ordained MWD in a real process. Particular attention is given to the development of a neural network model for predicting the instantaneous reactor feed conditions for a specified product MWD and characterising the MWD for the purpose of dimension reduction using principal component analysis. Data collected from a simulated ideal reactor process are used in the study. The way in which this approach will underpin a real laboratory-scale polymerisation system is briefly outlined.