Kinetics Organic inorganic composites

In order to achieve more control of methanol crossover, composite membranes are synthesized. Organic-inorganic composite membranes comprising Nafion with inorganic materials silica, mesoporous zirconium phosphate (MZP) and mesoporous titanium phosphate (MTP) are made as proton-exchange-membrane electrolytes for direct methanol fuel cells (DMFCs) [206] with increase in proton conductivity and low methanol crossover. Composite membranes with mordenite incorporated in polyvinyl alcohol-polystyrene sulfonic acid blend tailored with varying degree of sulfonation also retards the methanol release kinetics considerably [199]. 

In the preparation of simultaneous networks, it is important to control both polymerizations rates. Systems with inorganic condensation rates much faster than the organic polymerization rates turn into brittle hybrids that shrink. The polymer content is low due to evaporation of unreacted monomer. Systems with fast organic polymerization rates usually show uncontrolled polymer precipitation leading to heterogeneous composites. In practice, the kinetics of polymerization are difficult to control, so the success of the simultaneous approach rests on the careful selection of the monomers and their composition. 

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