Single graft

Fig. 2.35).The synthesis and morphology of more complex trifunctional branched graft copolymers have recently been discussed. Gido et al. (1996) prepared PS2-PI-PS2 (H-shaped) and (PS-PI)PI(PS-PI) ( -shaped) copolymers (see Fig. 2.33). The observed morphology of these samples was compared to the theory of Milner, the comparison being facilitated by considering the H- and -shaped molecules to each be composed of two single graft copolymers. This generally produced a satisfactory mapping onto the phase diagram in Fig. 2.34.

By means of laser Raman spectroscopy two characteristic band were found at 996 and 285 cm for vanadia on titania catalysts which were assigned to V=0 groups [42]. A band at 1030 cm from a singly grafted catalyst was assigned to small vanadia clusters [25],... 

Fig. 12.5 Possible types of compatibiliser (a) diblock, (b) triblock, (c) multigraft and (d) single-graft copolymers at the interface of a heterogeneous polymer blend. A and B represent the two components of the blend O and represent the monomers of the blocks C and D, respectively, of the compatibilising molecules. (Adapted with permission of Elsevier Science.)...

Fig. 12.8 Schematic representations of various types of copolymers (a) random, (b) alternating, (c) diblock, (d) triblock, (e) single-graft, (f) multigraft and (g) cross-linked graft.

Dfmer to Single Graft ratio Graft Method Polymer... 

Mechanism proposed to explain preponderance of single graft onto LDPE. (from ref 11). 

Exact graft copolsrmers having rather simple structures, ie one or two branches, have been prepared so far. Among these are the A2B and AA B single graft copolymers (121-128) and the H- and -shaped copolymers (129-131) (Fig. 10). Several techniques have been used for the ssmthesis of these structures and mainly anionic polymerization and controlled chlorosilane chemistry. 

When multifunctional polymers are used in reactive compatibilization (see Alternatives 2 and 3), their reactive group content (RGC) is expected to influence the extent of the interfacial reaction (at constant blend composition) and the molecular architecture of the in situ formed compatibilizer. For instance, there must be a change from a single graft to a multiple-graft comb-like structure, as the RGC of one of the two reactive polymers is increased. This change in the molecular architecture can affect the stability of the compatibilizer at the interface and its physical entanglement with the chains in the phases to be compatibilized. Finally, the RGC of multifunctional preciu ors may also have an effect on the miscibility with the nonfunctional chains in which they are dispersed. 

Figure 2.5 TEM of a single-grafted MCWNT coated by a thin layer of PS. Scale bar 25 nm. (From Ref. 66. Reprinted with permission of the Royal Society of Chemistry]...

While most fundamental studies of model block copolymers have focused on diblock and triblock architectures due primarily to synthesis considerations, several nonlinear designs, such as the star, miktoarm and single-graft motifs, have likewise been investigated. Self-organization of such copolymers has yielded morphologies that, in some cases, differ markedly from those observed in comparable linear copolymer systems [178,179]. Recall that a morphological transformation in conventional copolymer/homopolymer blends reflects a... 

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