Mass Transfer Mediated by a Vapour Phase

This is probably the most studied mechanism of mechanochemical co-crystal formation. Co-crystallisation mediated by molecular diffusion through the vapour is likely to occur in cases where one or both reactants exhibit significant vapour pressures. Product formation is expected then to occur readily upon 

A possible explanation is that mechanochemical grinding can play a more important role in co-crystallisation than simply mixing volatile reactants. 

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