Preparation and characterization of poly(glycidyl methacrylate) grafted from magnesium hydroxide particles via SI-ATRP

In order to improve the compatibility of magnesium hydroxide particles [Mg(OH)2] and polymer matrix, poly(glycidyl methacrylate) (PGMA) grafted from magnesium hydroxide particles were synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP). In this work, two approaches for the immobilization of ATRP initiator on the magnesium hydroxide particles surface were compared and selected. The density of initiator was significantly increased by the method of introducing more hydroxyl groups via ATRP of 2-hydroxyethyl methacrylate (HEMA) on the surface. The percentage of bromine atom for the initiator-functionalized magnesium hydroxide particles [Mg(OH)2-g-PHEMA-Br] reached to 1.75%, compared to 0.48% for Mg(OH)2-Br determined by XPS analysis. The surface-initiated ATRP of glycidyl methacrylate (GMA) can be conducted in a controlled manner, as revealed by the linear kinetic plot, linear increase of number average molecular weight (Mn) with monomer conversions, and the relatively narrow molecular weight distributions (Mw/Mn ∼ 1.4) of PGMA chains. The percentage of grafting PG (%) and the thickness of the grafted polymer layer increased with the increasing of polymerization time and reached to 116.6% and 197.6 nm after 300 min respectively. As for the polymerization with different initial monomer concentration, the number average molecular weights (Mn) and weight average molecular weights (Mw) of PGMA increased with the increasing of initial monomer concentration. TGA indicated that the initial decomposition temperature of Mg(OH)2-g-PHEMA-PGMA composite particles (253 °C) was much lower than that of unmodified magnesium hydroxide particles (337 °C).

► PGMA grafted from Mg(OH)2 particles were synthesized via SI-ATRP. ► The density of initiator on the surface was significantly increased by introducing more hydroxyl groups via ATRP of HEMA on the surface. ► The percentage of grafting PG (%) of PGMA on Mg(OH)2 particles reached to 116.6%. ► The thickness of the grafted polymer layer increased with the increasing of polymerization time and reached to 197.6 nm after 300 min. ► The initial decomposition temperature of Mg(OH)2-g-PHEMA-PGMA composite particles (253 °C) is much lower than that of untreated magnesium hydroxide (337 °C).