Block copolymers from functional polymers

Block Copolymers from Prepolymers Synthesised by the Reaction of Azo Compounds with Functionalized Polymers... 

From functionalized polymers or copolymers, complex mixtures of several monomers, small oligomers, and other products may arise upon degradation. In such cases, it is advantageous to use GC/MS, which makes it possible to obtain mass spectra of the single-mixture constituents. The mass spectra identify the individual components, while the total ion chromatograms reconstructed from the spectra reveal quantitative compositional information about the polymer, for example, the proportion of oligomers in a random or block copolymer. GC/MS of pyrolyzed polymers is covered in considerable detail in Chapter 3. 

Scheme 5.10 Synthesis of norbornene-functionalized MWCNTs, and the subsequent grafting polymer and block copolymer from CNT surfaces by ROMP. ...

The properties of the linear material 7.27 and the network copolymer 7.28 have been studied by dynamic mechanical analysis, DSC, and transmission electron microscopy. Evidence was obtained for the formation of highly ordered micro-phase-separated superstructures in the solid state from the materials 7.27. The Cu(bipy)2 moieties appear to form ordered stacks, and this leads to thermoplastic elastomer properties. In contrast, the network structure of 7.28 prevents significant microphase separation [51-53]. By means of related approaches, dinuclear Cu helical complexes have also been used to create block copolymers by functioning as cores [54], and polymer networks have also been formed by using diiron(II) triple helicates as cores for the formation of copolymers with methyl methacrylate [55]. 

Tunca et al. [27, 28,38] reported in a series of papers on a multi-click approach for the preparation of brush copolymers. The backbone consisted of homopolymers, statistical polymers, or block copolymers from ONBEs with orthogonal side groups for Diels-Alder click reaction [27,28,38], azide/alkyne click reaction, [27, 28, 38] and nitroxide coupling [27]. In a grafting-to approach, maleimide-or ONBE-functionalized polymers (PEG, P BA, PMMA (56)) were attached by Diels-Alder click reaction with the anthracene groups pendant at the polymer backbone (55) (Scheme 9.8b). PCL chains were attached by an azide/alkyne click reaction, while a combination of Diels-Alder and azide/alkyne click reaction allowed the synthesis of graft copolymers with PS-/ -PEG-, PS-h-PMMA-, or PS-/ -P BA side chains. 

The most successful methods for the preparation of block copolymers from polymer lamellas to date are apparently those involving addition reactions. The reaction conditions are relatively mild and the reaction is specific. Complete conversion of the functional groups (double bonds) in the folds and noncrystallizing ends apparently takes place whereas for substitution and elimination reactions, this has not been shown to be exclusively the case. 

Block copolymers based on polymers formed by other mechanisms can be made by first preparing an end-funrtional prepolymer which is converted to a polymer with thiocarbo-nylthio groups by end-group transformation. This is then used as a macro-RAFT agent in preparation of the desired block copolymer (Scheme 34). We first exploited this methodology to prepare PEO-Wocfe-PSt from commerdally available hydroxy end-functional... 

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