Grafting-from strategy

So far, the grafting from strategy has proven to be the most successful one for the preparation of cylindrical brushes. Both anionic [30, 31, 142, 143] and cationic [29] polyelectrolyte cylindrical brushes with well-defined backbones and side chains were prepared. We have also prepared core-shell brushes with PAA as the core or shell, which will be discussed later [30, 31], Recently we have been able to prepare strong anionic brushes with sulfonate groups by direct ATRP of ionic monomers in organic solvent [144],... 

Controlled polymerization techniques have enabled the preparation of well-defined polyelectrolytes of different architectures. Polyelectrolyte stars and cylindrical brushes are two typical examples with isotropic and anisotropic nature, respectively. Different synthetic strategies have been developed for these polyelectrolytes. However, the core first and grafting from strategies have turned out to be the most suitable methods for the synthesis of polyelectrolyte stars and cylindrical brushes. 

Figure 1.2 Functional polymer layers on surfaces produced with (a) grafting to and (b) grafting from strategies, (a) In grafting-to processes, preformed polymer chains containing a linker group (B) are chemically bound to anchor groups (A), (b) In grafting-from, polymerization of a monomer (M) is started from initiators (I) bound to the surface.

An example of the grafting from strategy is a treatment of SWNTs with sec-butyllithium that generates carbanions on the nanotube surface. These carbanions can serve as initiators of anionic polymerisation of styrene for in situ preparation of polystyrene-grafted tubes. This procedure allows the debundling of SWNTs and the production of a homogeneous dispersion of nanotubes in polystyrene solution. 

In conclusion, the grafting-from strategy had in the last few years been established as a most versatile approach towards thin-layer MIP materials, which is also very useful for further elucidation of MIP structure and recognition function. 

PDI, and the architecture of the resulting molecular brushes. For examples, by making use of a star-shaped polyinitiator backbone instead of normal linear ones could produce multiarmed CPBs [107]. By using a PEOMA (M = 1100 g moP ) macromonomer instead of a normal monomer in the grafting-from strategy, double-grafted brushes have been prepared from a normal linear polyinitiator backbone [23]. 

Scheme 30.20 Preparation of a heterofunctional hyperbranched polymer via the self-condensing ATRP of an azide-functional inimer and subsequent click coupling combined with the grafting-from strategy to afford multihetero-arm hyperbranched brushes. Reproduced with permission from Ref [149] 2009, The Royal Society of Chemistry.

The grafting though, grafting onto, and grafting from strategies have been considered as powerful tools in the preparation of molecular brushes with different chemical composition and... 

---