Biomimetic fabrication of vaterite film from amorphous calcium carbonate on polymer melt: Effect of polymer chain mobility and functionality

We demonstrate that amorphous calcium carbonate (ACC) thin film crystallization on poly(epsilon-caprolactone) (PCL), poly(bisphenol A carbonate) (PC), poly(tert-butyl acrylate) (PtBA), and poly(methyl methacrylate) (PMMA) substrates is affected by the chain mobility and functionality of the polymers above and below their melting and glass transition temperatures. ACE films are transformed into metastable (004) vaterite films on PCL and PMMA melts and are transformed into thermodynamically stable calcite (110) films on PC and PtBA substrates at 100 degreesC. On the basis of our results, we suggest that, in the melt phase, polymer chains containing ester groups trigger the formation of oriented vaterite films through interactions between the ester functionalities and ionic species present in ACC. In contrast, less reactive ester groups in polymer substrates, as well as esters in the solid phase, were found not to affect the kinetic growth of CaCO3 crystals in ACC in air. A comparison of the ACC film crystallization processes on PCL and PC established a dependency on the chain mobility of the polymers, and on PtBA and PMMA, it was confirmed that the ester group reactivity also affects the crystallization of ACC films.