Postpolymerization functionalization

Fang and Yamamoto [351] reported on postpolymerization functionalization of triarylamine-fluorene copolymer 253, resulting in copolymers 254a,b with stilbene pendant groups. Whereas in the solid-state absorption and PL maxima of both polymers are essentially the same, PL in solution is strongly influenced by solvent (from 433 nm in toluene to 466 nm in jY-methylpyrrolidone). Copolymer 254a showed d>PL in the solid state of 51%, comparable to that of poly(9,9-dialkylfluorenes) (Chart 2.66). 

Side chain functionalization of covalently functionalized pol5mers can take place either by prepolymerization functionalization, which is the functionality that has been bestowed to the monomer, or by postpolymerization functionalization, which is after the polymerization, when the polymer backbone is subsequently functionalized with the desired moiety (Pollino and Week 2005). Although both approaches have been employed successfully in covalent pol5mer chemistry, the first approach can be synthetically more demanding but always yields 100% functionalization, which is not the case for most postpolymerization functionalization strategies. 

Liu, J.S. and McCullough, R.D., End group modification of regioregular polythiophene through postpolymerization functionalization, Macromolecules 35, 9882-9889, 2002. 

The book contains 22 chapters, logically organized into an overview chapter with three other subsections Part one The synthesis of functional polymers by direct methods, such as anionic, cationic, free radical and coordination polymerization. Part two The synthesis of functional polymers by postpolymerization functionalization. Part three Novel approaches and structures. Special emphasis is given to more modem techniques Aat allow for controlled and directed functionalization via living polymerization. 

The postpolymerization functionalization method to incorporate transition metals into hyperbranched polymer... 

Modification of the entire polymer backbone via postpolymerization functionalization (polymer-analogous reactions)... 

Most of the aforementioned copolymers are subjected to further chemical reactions after copolymerization in order to extend or alter the functionality introduced. Apart from that a classic field of postpolymerization functionalization exists where PLA in its pure form is chemically or sometimes physically treated to introduce reactive sites into the polymer chains that can be used as starting points for functionahzation reactions. These methods however are in most cases limited to the polymer surface since applying the procedures to the dissolved polymer would in many cases lead to severe chain degradation. In any case, polymer chain degradation is an issue that has to be kept in mind for most of the postpolymerization functionalization techniques. 

Zhai, L, R.L. Pilston, K.L. Zaiger, K.K. Stokes, and R.D. McCullough. 2003. A simple method to generate side-chain derivatives of regioregular polythiophene via the GRIM metathesis and postpolymerization functionalization. Macromolecules 36 (l) 61-64. 

Copolymerizations of ethene with bicycUc olefins, such as 2,5-norbomadiene and 5-vinyl-2-norbomene, have been investigated with metallocene catalysts. The secondary groups do not interfere with metallocene copolymerizations, and postpolymerization functionalization makes it possible to synthesize functionalized polyolefins [133-135]. 

Benanti, T.L., Kalaydjian, A., and Venkataraman, D. (2008) Protocols for efficient postpolymerization functionalization of regioregular polythiophenes. Macromolecules, 41,8312—8315. 

Xue C, Donum VRR, Liu H (2006) Facile, versatile prepolymerization and postpolymerization functionalization approaches for well-defined fluorescent conjugated fluoiene-based glycopolymers. Macromolecules 39(17) 5747-5752... 

Scheme 33 Postpolymerization functionalization of co-telechelic transferable Br atoms.

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