Comb and graft copolymers

The studies of Rg as well as Rrl and Rh of a number of dendrimer systems establish a transition from v=0.45+0.05 to v=0.25+0.05 dependence on MW as shown in Figs. 4 and 5. This result is qualitatively consistent with the simulation results and has several consequences. Because [q] -R- /M, the value of [q] will increase with the MW of the dendrimer when v>l/3, be independent of MW when v=l/3,and decrease with MW when v< 1/3. This last, unusual, behavior of high MW dendrimers has been pointed out [48]. The maximum in the value of [q] at intermediate MW resembles the behavior of star polymers when values of [q] are plotted against f, the arm functionality at constant arm MW [62,81]. It is also observed in comb and graft copolymers with increasing grafting density, other variables being kept constant [82]. 

WEB Weber, C., Krieg, A., Paulus, R.M., Lambermont-Thijs, H.M.L., Becer, C.R., Hoogenboom, R., and Schubert, U.S., Thermal properties of oligo(2-ethyl-2-oxazoline) containing comb and graft copolymers and their aqueous solutions,... 

Synthesis of comb (regular graft) copolymers having a PDMS backbone and polyethylene oxide) teeth was reported 344). These copolymers were obtained by the reaction of poly(hydrogen,methyl)siloxane and monohydroxy-terminated polyethylene oxide) in benzene or toluene solution using triethylamine as catalyst. All the polymers obtained were reported to be liquids at room temperature. The copolymers were then thermally crosslinked at 150 °C. Conductivities of the lithium salts of the copolymers and the networks were determined. 

Organosilicone surfactants can be classified according to the position of the lyophilic moiety with respect to the Si-O-Si polymer. The abbreviations M, D, T and Q, referring to the number of oxygen atoms bonded to the silicon, are used to define the silicone portion as shown in Table 2.8.2. Insertion of the lyophilic moiety (A) into the silicone polymer itself leads to monofunctional, i.e. M(D A)M, and polyfunctional linear, i.e. MID A D M, type surfactants. Polyfunctional linear versions are also described as rake, comb- or graft-copolymers. Substitution at the ends of the silicone polymer yields surfactants... 

The reaction scheme is very general, but control over the extent of the intermolecular reactions and the distribution of the number of arms in the star is limited. The arm first method includes the polymerization (to form star polymers) or copolymerization (to form comb or graft copolymers) of macromonomers. The technique provides a handy simplification if the arm MW need not be very high and the MW control of the branched polymers is not very important. 

The completely cationic synthesis of comb or graft copolymers have yet to be realized [103]. However, numerous backbone polymers, branches and macromonomers have been prepared separately via cationic polymerization and these have been combined with other grafting and polymerization processes to prepare (co)polymers that cannot easily be prepared otherwise [103]. 

This chapter is concerned primarily with the simultaneous polymerization of two monomers to produce statistical and alternating copolymers. The different monomers compete with each other to add to propagating centers, which can be radical or ionic. Graft and block copolymers are not synthesized by the simultaneous and competititive polymerization of two monomers. Each monomer undergoes polymerization alone. A sequence of separate, noncompetitive polymerizations is used to incorporate the different monomers into one polymer chain. The synthesis of block and graft copolymers and variations thereof (e.g., star, comb) are described in Secs. 3-15b-4, 3-15b-5, 5-4, and 9-9. 

Macromonomers provide an easy access to a large number of functional copolymers and controlled topologies, such as comb-like, star-like, bottle brush, and graft copolymers. These types exhibit exceptional solution or solid state properties compared to their linear homologues. 

Comb-like graft copolymers with polysilane backbone and poly(IBVE) branches were reported by Matyjaszewski and Hrkach [61]. The IBVE monomer was grafted from triflated poly(methylphenyl silylene) at -30 °C using acetone as a... 

Figure 1 Different types of polyphosphazenes including linear classical macromolecules (1), star structures (2), block copolymers (3), cyclolinear polymers (4), and comb or graft copolymers (5) and (6). Not shown are cyclomatrix materials in which cyclic trim eric rings are connected in three dimensions ...

Anionic polymerization of functionalized cyclotrisiloxanes is a good method for the synthesis of well-defined functionalized polysiloxane with control of molecular mass, polydispersion, and density and arrangement of functional groups. These polymers may serve as reactive blocks for the building of macromolecular architectures, such as all-siloxane and organic-siloxane block and graft copolymers, star-, comb- and dendritic-branched copolymers and various polysiloxane-inorganic solid hybrids. 

Most importantly, these chain-functionalized polymers can be utilized as versatile precursory polymers for the creation of macromonomers, block and graft copolymers, comb-Hke polymers, cyclic polymers, hyperbranched polymers, and polymer networks. 

Macromonomers with a terminal non(homo)polymerizable vinylidene group, such as DPE, have gained much attention in recent years. One of the most unique and appeaUng applications of these types of macromonomers is that they can be used as precursor polymers for a variety of block copolymers with controlled architectures such as ABC-type star-block or comb-type graft copolymers. )-DPE functionalized macromonomers could be prepared by the addition reaction of hving cationic polymers to double diphenylethylenes such as l,3-bis(l-phenylethenyl)benzene (meta-double diphenylethylene, MDDPE) or l,4-bis(l-phenylethenyl)benzene (para-double diphenylethylene, PDDPE) [164]. 

WUG Wu, G., Chen, S.-C., Zhan, Q., and Wang, Y.-Z., Well-defined amphiphilic biodegradable comb-like graft copolymers Their rmique architecture-determined LCST and UCST thermoresponsivity. Macromolecules, 44, 999, 2011. 

Figure 8. Examples of three groups of carbon dioxide soluble stabilizers (homopolymers, block copolymers, comb-like graft copolymers) used in dispersion polymerizations in carbon dioxide. They consistof lipophilic and carbon dixoide-philie groups. Lipohilic groups function as anchors by attaching to the growing polymer particles, while their carbon dioxide-liking segments extend into the carbon dioxide continuous phase providing the stability.

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