Bimodal Polymer-grafted Nanoparticles with Precisely Controlled Structures

A series of poly(3-(triethoxysilyl)propyl methacrylate) (PTEPM) oligomers (oT), polymethylmethacrylate (PMMA) oligomers (oM), and block copolymers of PTEPM-b-PMMA with narrow molecular weight distributions were synthesized using RAFT polymerization. Two PTEPM-b-PMMA copolymers with the PMMA blocks of different molecular weights were co-assembled with the oligomers of PMMA or PTEPM to form various ordered nanoscale structures, such as lamellae, cylinders, and spheres. PTEPM block could be crosslinked to form silsesquioxane core (i.e., SiO1.5), when the obtained co-assembly materials were immersed in hydrochloric acid atmosphere. After appropriate separation and purification, the bimodal polymer grafted nanoparticles (PGNPs) with different microstructures could be prepared. Using this assembling-crosslinking-dispersing (ACD) method and adjusting the molecular structure of block copolymer and the ratio of the three components (PTEPM-b-PMMA, oT, and oM), the structural parameters of bimodal PGNPs, including the shape and size of core, grafting density, molar ratio between long and short brushes, and length of long brushes, could be precisely controlled. By adjusting the proportions of two block copolymers with the PMMA blocks of different molecular weights and the amounts of oMs, bimodal PGNPs with different molar ratios of long and short brushes could be prepared. By adjusting the molecular weight of the long brush and the amounts of oM, bimodal PGNPs with different lengths of long brushes were obtained. By adjusting the amounts of oM and oT, bimodal PGNPs with the same core shape but different sizes were obtained. By adjusting the amounts of oM, bimodal PGNPs with the same core weight but different shapes (cylindrical or spherical) were obtained. These nanoparticles are ideal model models for studying the relationship between the microstructures and properties of polymer nanocomposites.

Automated summary

A series of poly(3-(triethoxysilyl)propyl methacrylate) (PTEPM) oligomers, polymethylmethacrylate (PMMA) oligomers, and block copolymers of PTEPM-b-PMMA were synthesized using RAFT polymerization. The copolymers were then co-assembled with PMMA or PTEPM oligomers to form ordered nanoscale structures, and the PTEPM block was crosslinked to form silsesquioxane core when immersed in hydrochloric acid atmosphere. By adjusting the molecular structure of the block copolymer and the ratio of the components, the structural parameters of the nanoparticles could be precisely controlled. These nanoparticles are important for studying the relationship between the microstructures and properties of polymer nanocomposites.