Synthesis of amphiphilic triblock copolymers for the formation of magnesium fluoride (MgF 2 ) nanoparticles

A series of amphiphilic poly(2‐hydroxyethyl methacrylate)‐ b ‐polydimethylsiloxane‐ b ‐poly(2‐hydroxyethyl methacrylate) (pHEMA‐ b ‐PDMS‐ b ‐pHEMA) (A‐B‐A) triblock copolymers were synthesized from three different carbinol‐terminated polydimethylsiloxanes with varying molecular weight. A carbinol‐terminated polydimethylsiloxane was modified with 2‐bromoisobutyryl bromide to obtain a macroinitiator. The block copolymers were characterized by NMR, GPC, and dynamic light scattering (DLS). Reverse micelles of a copolymer were formed in mixture of benzene/methanol solution which served as nanoreactors for the synthesis of magnesium fluoride (MgF 2 ) nanoparticles. The MgF 2 was prepared via chemical precipitation using magnesium chloride and potassium fluoride as reactants. The MgF 2 ‐triblock copolymer composites were synthesized as a function of MgF 2 –weight ratio (0.5, 5, and 10 wt%) in copolymer. The MgF 2 colloids were dissolved in three organic solvents: methanol, iso propanol, and tetrahydrofuran. The polymer nanoparticles were characterized by DLS, transmission electron microscopy, thermogravimetric analysis, and X‐ray diffraction (XRD) analysis. The formation of MgF 2 crystals was observed by XRD. Particle size and particle size distribution showed significant changes in different solvents. The thermal stability of MgF 2 colloids increased as the amount of nanoparticle increased in polymeric matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012