Since the pristine material consists of propanol intercalated ZrP nanosheets, initially the phosphonic acid can easily diffuse within the layers and react. As the reaction proceeds, the reacted phase will result enriched in phosphonate groups and, especially at high R values, the protruding and rigid phenylphosphonate groups are expected to hamper the diffusion of additional phosphonic acid molecules within the interlayer space and their reaction with Zr(IV).