Influence of Chitosan Grafted Poly(vinyl Sulfonic Acid) as Template on the Calcium Carbonate Crystallization
A. Neira-Carrilloa,*, P. Mercadé-Jaquec, M. Diaz-Dosqueb, C. Tapia-Villanuevac and M. Yazdani-Pedramc
aFaculty of Veterinary and Animal Sciences, Universidad de Chile
bFaculty of Odontology, University of Chile, Santiago, Chile
cFaculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago, Chile
Chitosan was grafted with polyvinylsulfonic acid (CHI-graft-PVS) through either chemical activation (CA) or ultrasound radiation (US) methods and the percentages of grafting (%G), grafting efficiency (%E) and the average degree of polymerization (R) were determined. The effect of CHI-graft-PVS as templates for in vitro crystallization of CaCO3 was evaluated by using gas diffusion method at different pH. It was found that CHI-graft-PVS act as an efficient modifier of crystal morphology or inhibit the crystallization depending on the experimental media and the method of grafting used. SEM analysis revealed that CHI-graft-PVS obtained through US method act as an inhibitor for CaCO3 crystallization. When CHI-graft-PVS from CA method was used, SEM analysis showed different CaCO3 morphologies such as spherical, prismatic, biconcave and needle-like crystals. Additionally, EDS confirmed the presence of S atoms from CHI-graft-PVS adsorbed on the surface of CaCO3 crystals. Results indicated that CHI-graft-PVS controls the nucleation, polymorphs and morphology of CaCO3 crystals. The composition of this new template and the control of pH of the mineralization solution seem to be crucial during CaCO3 crystallization. CHI-graft-PVS template represents an alternative approach for understanding the biomineralization process and offers a wide range of possibility for polymer controlled crystallization.
Keywords: Poly(vinyl sulfonic acid) grafted chitosan, Polymeric template, Gas diffusion method, Crystallization, Calcium carbonate