Surface-grafted RAFT polymerization

Synthetic Strategies for Surface-Grafted RAFT Polymerization. 80... 

In order to graft polymer from CNTs surfaces by RAFT polymerization, the CTAs should be immobilized on the surface firstly (whieh is quite similar to the cases of ATRP to produce the CNT-based macroinitiator). Various approaches to macroCTAs are shown in Scheme 5.5, and the results are... 

FIGURE 6.8 (a) Schematic illustration of the procedure for the synthesis of polymeric capsules based on surface-initiated RAFT polymerization using silica nanoparticles as templates, (b) TEM image of polymer grafted silica nanoparticles, (c) SEM and (d) TEM images of the synthesized polymeric capsules. Source Huang et al. [15]. Reproduced with permission of American Chemical Society. 

The preparation of polymer brushes by controlled radical polymerization from appropriately functionalized polymer chains, surfaces or particles by a grafting from approach has recently attracted a lot of attention.742 743 The advantages of growing a polymer brush directly on a surface include well-defined grafts, when the polymerization kinetics exhibit living character, and stability due to covalent attachment of the polymer chains to the surface. Most work has used ATRP or NMP, though papers on the use of RAFT polymerization in this context also have begun to appear. 

Baum et al. apphed RAFT polymerization to synthesize brushes of PS, PMMA, poly(Nd -dimethylacrylamide) (PDMA), and their copolymers on azo-initiator-bound sihcate surfaces [127]. 2-Phenylprop-2-yl dithiobenzoate was added as a free (unboimd) RAFT agent to control the graft polymerization. Because of a very low concentration of surface-bound initiator, a free... 

Polymer-linked MWCNT nanocomposites were prepared by reversible addition fragmentation chain transfer (RAFT). The RAFT reagent was successfully grafted on to the surface of MWCNTs and PS chains were grafted from MWCNTs via RAFT polymerization [192], By covalently linking acyl chloride functions of functionalized MWCNTs with living polystyryllithium, Huang et al. succeeded in the preparation of polystyrene-functionalized MWCNTs (Scheme 1.32) [193],... 

The proposed reaction mechanism for RAFT polymerization under a constant source of y-radiation is shown in Scheme 3. The basic steps of the RAFT mechanism are extended by reaction steps that effect grafting onto polymeric surfaces. 

Scheme 3. Possible RAFT mechanism for initiatedpolymerization and grafting onto polymeric solid surfaces [14]...

Roy D, Knapp JS, Guthrie JT, Perrier S (2008) Antibacterial cellulose fiber via RAFT surface graft polymerization. Biranaraomolecules 9 91—99... 

Due to the relative ease of control, temperature is one of the most widely used external stimuli for the synthesis of stimulus-responsive bmshes. In this case, thermoresponsive polymer bmshes from poly(N-isopropylacrylamide) (PNIPAM) are the most intensively studied responsive bmshes that display a lower critical solution temperature (LOST) in a suitable solvent. Below the critical point, the polymer chains interact preferentially with the solvent and adopt a swollen, extended conformation. Above the critical point, the polymer chains collapse as they become more solvophobic. Jayachandran et reported the synthesis of PNIPAM homopolymer and block copolymer brushes on the surface of latex particles by aqueous ATRP. Urey demonstrated that PNIPAM brushes were sensitive to temperature and salt concentration. Zhu et synthesized Au-NPs stabilized with thiol-terminated PNIPAM via the grafting to approach. These thermosensitive Au-NPs exhibit a sharp, reversible, dear opaque transition in solution between 25 and 30 °C. Shan et al. prepared PNIPAM-coated Au-NPs using both grafting to and graft from approaches. Lv et al. prepared dual-sensitive polymer by reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide from trithiocarbonate groups linked to dextran and sucdnoylation of dextran after polymerization. Such dextran-based dual-sensitive polymer is employed to endow Au-NPs with stability and pH and temperature sensitivity. 

Polymers of acrylamide (PAAm) represent an important class of materials because of applications such as in coatings, occulants, paper making, mining, electrophoresis, and biology. While RAFT polymerization and click chemistry can be used for surface modi cation by both grafting to and... 

Hong, C.Y. You, Y.Z. Pan, C.Y. (2005). Synthesis of Water-Soluble Multiwalled Carbon Nanotubes with Grafted Temperature-Responsive Shells by Surface RAFT Polymerization. Chemistry of Materials, 17, 2247- 2254. 

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