Grafting-from method

Grafting from methods involve creation of metalated sites on a polymer backbone, and subsequent use of these sites to initiate the polymerization of a second monomer. Several examples of such grafting processes have been described 135 ,39>. However, no control of the number and length of the grafts is provided, since some sites may be inaccessible to the incoming monomer. As no accurate characterization... 

ATRP and grafting from methods led to the synthesis of poly(styrene-g-tert-butyl acrylate)-fr-poly(ethylene-co-butylene)-fr-poly(styrene-g-ferf-butyl acrylate) block-graft copolymer [203]. ATRP initiating sites were produced along the PS blocks by chloromethylation as shown in Scheme 112. These sites then served to polymerize the ferf-butyl acrylate. The poly(ferf-butyl acrylate) grafts were hydrolyzed to result in the corresponding poly(acrylic... 

Grafting from method, 7 652-653 Grafting onto method, 7 654 Grafting process, 73 537 Grafting through method, 7 653 Graft polymerization. See also Graft copolymerization ABS, 7 419, 421 acrylic ester monomers, 7 386 of methacrylic ester polymers, 76 289-290... 

Characterization results have been reported for dendrigraft-polylpthylene ox-ide)s of generation Gl, prepared by adding different amounts of ethylene oxide to the initiator core in the side chain growth reaction (Table 9.8). Because of the grafting from method used, the molecular weight of the polyethylene oxide) branches cannot be accurately determined, and hence it is impossible to confirm... 

An alternative approach for covalent polymer attachment is called the grafting from method. This method is based on binding the monomer precursor to the nanotube and generating chain growth directly from the tube. By these means, several types of polymers could be grafted, such as polystyrene-sulfonate [46], polyvinylpyri-dine [47], polystyrene [48] and many others. 

Turgman-Cohen, S. and J. Genzer, Computer simulation of controlled radical polymerization Effect of chain confinement due to initiator grafting density and solvent quality in "grafting from Method. Macromolecules, 2010. 43(22) p. 9567-9577. 

Minko, S., Grafting on Solid Surfaces Grafting to and Grafting from Methods, in Polymer Surfaces and Interfaces, M. Stamm, Editor. 2008, Springer Berlin Heidelberg, p. 215-234. 

Qin, S., et al., Functionalization of single-walled carbon nanotubes with polystyrene via grafting to and grafting from methods. Macromolecules, 2004. 37(3) p. 752-757. 

In a similar approach Riihe et al. [279] reported the preparation ofpoly(2-oxazoline) brushes by the grafting onto as well as grafting from method. For LCSIP of 2-ethyl-2-oxazolines silane functionalized undecane tosylate was first prepared and then immobilized on the substrate surface. SIP resulted in PEOx layers with thickness close to 30 nm. PEOx brushes were prepared by chemisorption of PEOx disulfides onto gold substrates. Preliminary static and dynamic swelling experiments are reported for these brushes. However, later observations [243] contradicted these findings. 

Fig.1 Schematic illustrating the formation of surface-anchored polymer assemblies by utilizing the grafting onto and grafting from methods...

In this review, synthesis of block copolymer brushes will be Hmited to the grafting-from method. Hussemann and coworkers [35] were one of the first groups to report copolymer brushes. They prepared the brushes on siUcate substrates using surface-initiated TEMPO-mediated radical polymerization. However, the copolymer brushes were not diblock copolymer brushes in a strict definition. The first block was PS, while the second block was a 1 1 random copolymer of styrene/MMA. Another early report was that of Maty-jaszewski and coworkers [36] who reported the synthesis of poly(styrene-h-ferf-butyl acrylate) brushes by atom transfer radical polymerization (ATRP). 

During the last 5 years, there have been several reports of multiblock copolymer brushes by the grafting-from method. The most common substrates are gold and silicon oxide layers but there have been reports of diblock brush formation on clay surfaces [37] and silicon-hydride surfaces [38]. Most of the newer reports have utilized ATRP [34,38-43] but there have been a couple of reports that utilized anionic polymerization [44, 45]. Zhao and co-workers [21,22] have used a combination of ATRP and nitroxide-mediated polymerization to prepare mixed poly(methyl methacrylate) (PMMA)Zpolystyrene (PS) brushes from a difunctional initiator. These Y-shaped brushes could be considered block copolymers that are surface immobilized at the block junction. 

Using the grafting-from method with NMP requires the synthesis and (co)polymerization of monomers that contain the nitroxide group [Hawker et al., 2001]. A halogen-containing monomer such as vinyl chloroacetate or p-chloromethylstyrene is reacted with an HO-containing alkoxyamine to yield a vinyl alkoxyamine, which is used as a NMP initiator to... 

RAFT has also been used to produce graft polymers. The grafting from method is achieved by reacting a halogen-containing polymer such as styrene p-chloromethy I styrene copolymer with sodium dithiohenzoate to obtain a polymeric dithioester, which is an initiator in RAFT polymerization (Sec. 3-15d) [Quinn et al., 2002]. 

In general, in the field of materials or condensed matter, the preparation of polymer brushes on solid surfaces is of great interest for surface modification and composite material preparation [4-6]. A number of model surface grafting techniques have been used on planar surfaces and particles and have been the subject of previous reviews. While a munber of polymer brush preparation methods have been reported using physisorption or chemisorption or so-called grafting onto methods, the emphasis of this review is on surface-initiated polymerization (SIP) methods or grafting from methods. 

Fig. 2.17 Synthesis of dendronised linear poly by the graft-from method (schematic)...

Dendrimers with their multiple end-standing functional groups are ideally suited for the construction of star-shaped polymers. Indeed, the end-standing functional groups can be used as initiators for polymerization ( grafting from method) or as functional groups for grafting onto . They can also be used as redistribution centers in equilibrium polymerization. 

The grafting from method is also successful in other ring opening polymerizations. For example, -caprolactone polymerization is initiated from polypropylene imine) dendrimers with n=2-16 end-standing amine groups [135]. To be... 

Graft polymers may be prepared by a variety of methods [221], including A. Grafting-from Method ... 

In another study, the same group attached 4-phenyl-pyridinium /V-oxide as pendant groups to the polychloromethyl styrene and its block copolymer with polystyrene via nucleophillic substitution with chloride as leaving group. The obtained macrophotoinitiators were used to obtain graft copolymers by grafting from method of MMA (Scheme 11.19, path a), and hydroxyl functionalization (Scheme 11.19, path b) [53]. 

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