Synthesis and characterization of self-assembled block copolymer templated calcium phosphate nanocomposite gels

Self-assembled macroscale calcium phosphate-copolymer nanocomposite gels were prepared using a bottom-up approach from aqueous solutions. Amphiphilic block copolymer micelles in aqueous solutions were used as templates for the growth of calcium phosphate nanocrystals and then allowed to self-assemble in solution to form thermoreversible nanocomposite gels. NMR and XRD showed that calcium phosphate precipitation in a Pluronic(R) F127 copolymer gel resulted in a disordered brushite phase while the calcium phosphate-poly(2-diethylaminoethyl methacrylate) (PDEAEM) modified Pluronic(R) F127 pentablock copolymer nanocomposite contained the same brushite phase along with a calcium dihydrogen phosphate second phase. TEM, SAXS, and NMR experiments confirmed that the calcium phosphate precipitated on and interacted with the polymer micelles forming an organized network of similar to 20 nm diameter nanospheres. The resulting polymer-calcium phosphate nanocomposite gels contained between 6.5 and 15 weight percent calcium phosphate, which could be controlled by manipulating the pH of the constituent solutions.