Synthesis of core/shell structure of glycidyl-functionalized poly(methyl methacrylate) latex nanoparticles via differential microemulsion polymerization

摘要

The differential microemulsion polymerization technique was used to synthesize the nanoparticles of glycidyl-functionalized poly(methyl methacrylate) or PMMA via a two-step process, by which the amount of sodium dodecyl sulfate (SDS) surfactant required was 1/217 of the monomer amount by weight and the surfactant/water ratio could be as low as 1/600. These surfactant levels are extremely low in comparison with those used in a conventional microemulsion polymerization system. The glycidyl-functionalized PMMA nanoparticles are composed of nanosized cores of high molecular weight PMMA and nano-thin shells of the random copolymer polyl(methyl methacrylate)-ran-(glycidyl methacrylate)l. The particle sizes were about 50 nm. The ratios of the glycidyl methacrylate in the glycidyl-functionalized PMMA were achieved at about 5-26 wt.%, depending on the reaction conditions. The molecular weight of glycidyl-functionalized PMMA was in the range of about 1 X 10(6) to 3 x 10(6) g mol(-1). The solid content of glycidyl-functionalized PMMA increased when the amount of added glycidyl methacrylate was increased. The glycidyl-functionalized polymer on the surface of nano-seed PMMA nanoparticles was a random copolymer which was confirmed by H-1-NMR spectroscopy. The amounts of functionalization were investigated by the titration of the glycidyl functional group. The structure of the glycidyl-functionalized PMMA nanoparticles was investigated by means of TEM. The glycidyl-functionalized PMMA has two regions of T-g which are at around 90 degrees C and 125 degrees C, respectively, of which the first one was attributed to the poly[(methyl methacrylate)-ran-(glycidyl methacrylate)] and the second one was due to the PMMA. A core/shell structure of the glycidyl-functionalized PMMA latex nanoparticles was observed.