Inorganic Particle Synthesis in Lyotropic Liquid Crystals
The main objective of this thesis is to investigate the crystallization of calcium phosphate in the lyotropic liquid crystal (LLC) systems formed by poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) amphiphilic block copolymers (Pluronics). Pluronics have the tendency to associate spontaneously to form various LLC structures (cubic, hexagonal and lamellar) at sufficiently high concentration (typically above 20 vt%). These various Pluronic LLC structures act as stable templates to control the polymorphs and morphologies of biominerals. The structure of LLC systems affects the polymorphic form of calcium phosphate. In the Pluronic L64 (EO 13 PO 30 EO 13 ) LLC system, small calcium phosphate particles with coarse surfaces prefer to form in H 1 LLC structure, while large calcium phosphate particles with layered surfaces are the main products in the L α and the H 2 LLC structures. The reaction time affects the polymorphs of calcium phosphate. Calcium phosphate formed in Pluronic LLC systems transforms from thermodynamically unstable dicalcium phosphate (DCP), octacalcium phosphate (OCP) to thermodynamically stable calcium deficient hydroxyapatite (CDHA) or hydroxyapatite (HA). According to FT-IR results in this work, the calcium phosphate particles formed in LLC structures are similar to bone apatite (Ca 10-x/2-x/2 [(HPO 4 )z(PO 4 ) 6-x-z CO 3 ) x ][(OH) 2-2y (CO 3 ) y ]. So they are promising biomaterials within the fields of injectable cements, implant coatings, and drug carriers.