Synthesis Of Amphiphilic Block Copolymer, Self-assembly And Mineralization Of Hydroxyapatite

In the rapidly developing field of biomaterials, pharmaceutical, biochemistry and polymer science, amphiphilic block copolymers have exhibited various interesting properties such as surface activity, aggregate formation, mineralization template and so on, which have made them as potential candidates advanced materials formation and engineering applications.Amphiphilic block copolymers:poly(ethylene glycol)-block-poly(acrylate acid)-block- poly (ε-caprolactone) (PEG-PAA-PCL) and poly(acrylate acid)-block-poly (s-caprolactone) (PAA-PCL) were synthesized via sequential anionic polymerization. The structures of the polymers were confirmed by 1H-NMR spectroscopy and gel permeation chromatography (GPC).The self-assembly behavior of the tirblock copolymer PEG-PAA-PCL in aqueous solution was studied by using dynamic light scattering (DLS). It shows the PAA segments not only affect the size of micelles but also respond to the pH changing. With variety of pH and block ratio, the size and distribution of micelles will be changed, which makes the copolymer designable for template.Hydroxyapatite (HA) mineralization was tuned using PEG-PAA-PCL as the template. The HA mineralization process was studied by using Ca+ ion selective electrode, TEM, SEM and zeta potential, which indicates the "reservoir" effect of micelle and the "barrier" effect of PEG segments. Besides that, the addition method of inorganic ions can influence the formation. The conversion mechanism of calcium phosphate to HA may be in terms of a diffusion-precipitation process.