Grafting-to route

Figure 20 Modes of grafting dendrimers or dendrons onto polymer backbones. Shown here are (A) the graft-to route, (B) the graft-front method, and (C) the macromonomer route. Source From Ref. 106.

Scheme 2 Comparison of sol-gel and grafting as routes to organically-functionalised...

Several features of this route to grafted PEO polymers are attractive. PEO is not very soluble in silicone, a property that can be exploited to direct reaction to interfaces. The ability to control degree of functionality at one or both ends of the PEO polymer permits independent control of crosslink density and total PEO content. Finally, any residual OH or allyl groups can be used for subsequent functionalization. We describe below strategies to graft in (co-cure) and graft to (post-cure) silicone elastomers with PEO. 

This chapter is concerned with just one of this class of thickeners, namely a hydrophobically modified (hydroxyethyl)cellulose (HMHEC), Hercules WSP D-47. Gelman and Barth (i) reported on the viscosity of such HMHECs. This sample contained up to four hexadecyl chains grafted to the cellulose backbone. The preparative route was that described by Landoll (2). The dilute solution properties were characterized by capillary viscom-etry, whereas the more concentrated solutions were characterized by continuous-shear viscometry, forced oscillation measurements, and shear-wave propagation. In addition, the adsorption onto polymer latex particles was investigated. 

For the cyclopropanation of styrene with EDA, Cu-polymerized 82 complexes afforded similar results than the non supported Box. In the first case 61% and 60% yield, 67/33 and 71/29 dr in favour of the trans, 93% and 94% ee were respectively observed. The catalytic system could be reused without loss of its catalytic properties. Moreover, it is noteworthy that the immobilization method did not influence the catalytic behaviour catalytic systems formed with copolymerized (route A) [84] or graft methodology (route B) [85] were substantially equivalent (variation of about 1 to 2% of the yield, ee or dr). 

In order to further improve the extent of dispersion of NFs inside matrix and to enhance the intimacy between the phases, modified ISP routes (Figure 1.50) have been developed that involve polymerization of suitable monomer chemically linked (or grafted) to the filler particles [513-520]. 

Figure 15 Grafting onto route to a strictly homologous series of first- through fourth-generation dendronized polymers PG1-PG4. ...

In the grafting to method (Fig. 2b), end-functionalized polymer chains are reacted with complementary functional groups located on the PSi surface to form tethered polymer chains (Minko 2008). The versatile chemistry of Si/Si02 allows functionalization of the PSi surface with a wide repertoire of reactive groups (Buriak 2002 Ciampi et al. 2008 Kilian et al. 2009a Alvarez et al. 2009 Jarvis et al. 2012). Some of the most common PSi functionalization routes are presented in Fig. 3. 

---