Surface Modification Of Nanomaterials With Hyperbranched Polymers

In recent years, organic/inorganic nanocomposites have attracted more and more attention and become one of the focuses in the area of materials due to excellent properties. The surface modification of the inorganic nanoparticles can reduce the surface energy of the nanoparticles, change the surface polarity of the nanoparticles, increase the affinity of the nanoparticles to the polymeric matrice, avoid aggregation of the nanoparticles and improve the dispersibility of the nanoparticle in polymeric matrice. It is helpful to understand the basic physical effects of nanoparticles, and enlarge the scope of its application. At present, the main methods of surface modification have surface reactive agent, in-situ polymerization and surface graft polymerization etc. The surface graft polymerization would further improve compatibility between the nanoparticles and polymeric matrice in order to fabricate more excellent nanocomposites.Hyperbranched polymers have attracted considerable attention because of their specific architecture, unique chemical and physical properties, and they have played a vital role in interface and surface sciences, which can be used advantageously as functional surfaces and interfacial materials. In addition, they have high solubility, low viscidity and high density of surface functional groups compared to linear analogues. Hyperbranched polymers have been synthesized in a one-pot route via self-polycondensation or an addition polymerization reaction of ABx-type monomer, self-condensation vinyl polymerization (SCVP), ring-opening polymerization (ROP) of latent AB_n monomers and so on. It is a promising route that hyperbranched polymer is used to surface-modify the nanoparticles.In this paper, hyperbranched (co)polymers modified inorganic nanoparticles and nanotubes have been prepared by self-condensing vinyl polymerization via surface-initiated atom transfer radical polymerization technique on the surface of silica nanoparticles, halloysite nanotubes. And the crosslinked polymeric nanocapsules with inner diameter of about 10-40nm were fabricated from silica templates grafted hyperbranched PCMS.1. Well-defined hyperbranched-graft copolymer grafted silica nanoparticles by consecutive the surface-initiated atom transfer radical polymerization We prepared the well-defined hyperbranched-graft copolymer grafted silica nanoparticles (SN-HBP-PMMA) by the surface-initiated atom transfer radical polymerization of methyl methacrylate from the hyperbranched polymer grafted silica nanoparticles (SN-HBP), via the self-condensing vinyl polymerization (SCVP) of p-chloromethyl styrene.2. Preparation of crosslinked polymeric nanocapsules by surface-initiated self-condensing vinyl polymerization on silica templatesWe develop a novel method for crosslinked polymeric nanocapsules with inner diameter of about 10-40nm from the nanosilica templates grafted hyperbranched polymers with amino-terminated hyperbranched polymers by the crosslinking with hexamethylene diisocyanate (HDI) after the surface end groups had been transformed to amino groups, then the nanosilica templates were removed by HF etching to produce the crosslinked polymeric nanocapsules. The hyperbranched polymer grafted silica nanoparticles (SN-HBP) prepared by the self-condensing vinyl polymerization (SCVP) of p-chloromethyl styrene.3. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerizationWe report a convenient method to modify the surface of HNT with a hyperbranched polymer and copolymer shell by surface-initiated self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl) oxy) ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization (SCVCP) of n-butyl acrylate (BA) and BAEA via atom transfer radical polymerization (ATRP) technique.