A facile strategy to modify TiO₂ nanoparticles via surface‐initiated ATRP of styrene

Abstract

A core-shell hybrid nanocomposites, possessing a hard core of nano titanium dioxide (n-TiO 2 ) and a soft shell of brushlike polystyrene (PS), were successfully prepared by surface-initiated atom transfer radical polymerization (ATRP) at 90 C in anisole solution using CuBr/PMDETA as the catalyst, in the presence of sacrificial initiator. FTIR, 1 H NMR, XPS, TEM, SEM, TGA, and DSC were used to determine the chemical structure, morphology, thermal properties, and the grafted PS quantities of the resulting products. TEM images of the samples provided direct evidence for the formation of a core-shell structure. The thermal stabilities of the grafted polymers were dramatically elevated relative to that of pristine PS according to TGA results. DSC results demonstrated that the TiO 2 -PS nanocomposites exhibited higher glass transition temperature (T g ) compared with pristine PS. The molecular weights of the free polymers formed by sacrificial initiator, which were similar to that of surface-attached polymers were measured by GPC instrument which showed that the molecular weights of PS were well controlled with a relatively narrow polydispersity index (PDI < 1.2).

Glycopolymer‐Grafted Polystyrene Nanospheres

“…Analogous to the synthesis of linear PtetAcGlc, the polymerization reached 95% after 90 min. Given that free polymer in solution and grafted chains have comparable molecular weights and polydispersities, [48][49][50][51][52] the resulting free polymer in solution could be easily characterized by means of GPC and hence no cleavage of the arms was necessary. After separation of the free polymer from glycopolymer brushes by repeated ultracentrifugation, the number-average molecular weight determined by means of GPC using PtBMA standards is M n ¼ 49 800 g Á mol À1 and the polydispersity index is M w =M n ¼ 1.12.…”

Surface Modification of Spherical Particles with Bioactive Glycopolymers

“…The chemo-enzymatic synthesis of 6-Omethacryloyl mannose and the formation of homopolymers and diblocks thereof has been described earlier. 38,43,44 Without the use of protecting group chemistry, RAFT polymerization seems to be the polymerization technique of choice to yield well-defined unprotected glycopolymers. In our case the previously used water/ethanol mixtures as the reaction medium were inappropriate to create a homogenous dispersion of the microsphere, which was overcome by changing the solvent to DMF.…”

“…This tempted researchers to synthesize diblock copolymers, in particular amphiphilic diblock copolymers containing a hydrophilic glycopolymer block and a hydrophobic block that can self-assemble into more complex structures. Emphasis was put in the synthesis of block copolymers containing glycopolymers and water-insoluble [41][42][43][44] or pH-/temperature-responsive polymers 41, 45-47 which self-assemble into micelles in aqueous solution. As an example, Zhang et al 47 described the preparation of a poly(acryloylglucosamine)-block-poly(Nisopropylacryamide) copolymer which formed micelles above the LCST of PNIPAAm and could be crosslinked by an acid-degradable acetyl-type crosslinking agent.…”

Grafting of amphiphilic polymers containing quaternary ammonium group on SiO2 surface via surface-initiated ATRP

“…2-Bromoisobutyrate-functionalized silica nanoparticles were then prepared via reaction of SiO 2 -NH 2 nanoparticles with BIBB. While the macroinitiators of SiO 2 coated with APTES-BIBB (Scheme 1 (b)) were synthesized by the reaction of ethoxy with hydroxy groups on the surface of silica nanoparticles [34]. Figure 3 showed the TGA weight loss curves of (a)pristine silica,(b) SiO 2 -NH 2 , (c) SiO 2 -A-Br, (d) SiO 2 -B-Br, (e) SiO 2 -g-B-P (DMAEMA8h-Q),and(f) SiO 2 -g-B-P (DMAEMA-16h-Q), respectively.…”