A novel method of surface-initiate atom transfer radical polymerization of styrene from silica nanoparticles for preparation of monodispersed core-shell hybrid nanospheres

• Published in: Journal of polymer research 2007-08, Vol.14 (4), p.253-260
• Main Authors: Zhang, Hong, Lei, Xiping, Su, Zhixing, Liu, Peng
• Format: Article
• Language: English
• Subjects: Analysis; Block copolymers; Chemical analysis; Coupling (molecular); Coupling agents; Differential scanning calorimetry; Glass; Glass transition temperature; Graft copolymers; Grafting; Initiators; Liquid chromatography; Methods; Methyl methacrylate; Molecular weight; Molecular weight distribution; Nanoparticles; Nanospheres; Polymer coatings; Polymerization; Polymers; Polymethyl methacrylate; Polystyrene resins; Radicals; Silica; Silicon dioxide; Styrenes
• ISSN: 1022-9760; 1572-8935
• DOI: 10.1007/s10965-007-9104-z

A new kind of initiator, 3-(2-bromo-2-methylacryloxy)propyltriethysiliane (MPTS-Br), was prepared with a simply hydrobrominated commercial silane coupling agent (3-methacryloxy-proplytriethysilane, MPTS). It has been one-step self-assemble onto the surface of silica nanoparticles, and by using this initiator-modified nanoparticle (SiO.sub.2-MPTS-Br) as macroinitiator for atom transfer radical polymerization (ATRP). Structurally well-defined homopolymer polystyrene (PS) and block polymer poly(styrene-b-methyl methacrylate) (PS-b-PMMA) chains were grown from the nanoparticles surface to yield individual particles composed of silica core and thick-coated polymer shell. The graft parameters could be calculated from the elemental analysis (EA) results, and linear plots of percentage of grafting (PG%) and conversion of monomer (C%) versus polymerizing time were achieved, respectively. Narrow molecular weight distribution (M.sub.w/M.sub.n) for the graft polymer samples were characterized by the gel permeation chromatography (GPC). The graft polymerizations exhibited the characteristics of the controlled/"living" polymerization. The glass transition temperature (T.sub.g) of SiO.sub.2-g-PS after polymerizing time of 24 h was found about 133 °C which was different from the polymer not grafted on the silica at 102 °C by the differential scanning calorimetry (DSC) analysis. The products were also characterized by FT-IR, XPS and TEM. The robustness and simplicity of this method may make large-scale manufacture of these polymer-coated nanospheres possible.