Chain Click reaction

Fig. 2. (a) TEM image of the gold nanorods capped with 4-azidobutane-1-thiol before the click reaction. The TEM image of the hexynelhiol-capped nanorods is similar to (a), (b) TEM image of chain like assemblies of gold nanorods obtained after the click reaction with 1 1 concentrations of A and B. The inset in (b) shows more complex assemblies of nanorods obtained by the click reaction with certain concentrations of A and B. 

Tsarevsky has found that hypervalent iodine compounds can be used for the direct azidation of polystyrene and consecutive click-type functionalization [49]. In particular, polystyrene can be directly azidated in 1,2-dichloroethane or chlorobenzene using a combination of trimethylsilyl azide and (diacetoxyiodo)benzene. 2D NMR HMBC spectra indicate that the azido groups are attached to the polymer backbone and also possibly to the aryl pendant groups. Approximately one in every 11 styrene units can be modified by using a ratio of PhI(OAc)2 to trimethylsilyl azide to styrene units of 1 2.1 1 at 0 °C for 4 h followed by heating to 50 °C for 2 h in chlorobenzene. The azidated polymers have been further used as backbone precursors in the synthesis of polymeric brushes with hydrophilic side chains via a copper-catalyzed click reaction with poly(ethylene oxide) monomethyl ether 4-pentynoate [49],... 

Nurmi L, Lindqvist J, Randev R, Syrett J, Haddleton DM (2009) Glycopolymers via catalytic chain transfer polymerisation (CCTP), Huisgens cycloaddition and thiol-ene double click reactions. Chem Commun 2727... 

If a PLA copolymer exclusively with ester linkages is required or desired but functional lactides are not available or only hard to obtain, copolymerization with functional lactones such as a-chloro-caprolactone [43] can be an alternative. The chlorine atom thus introduced into the copolymer chain can be substituted with an azide group amenable for click reactions with various alkynes. The strategies for the functionahzation of PCL are discussed in detail later on in this chapter. 

Due to the rather easy accessibility of novel functional polymer materials by click reactions, their potential scope of applications has significantly broadened in the last years. Through the preparation of functional thin polymer films, biohybrids, or self-assembly structures from end group or side chain functionalized polymers and functional block copolymers, applications, for example, as adhesives or additives, but especially also in optoelectronics, biomedicine, drug delivery, biochips, and micro- and nanoelectronics become accessible. 

Recently, well-defined AB2 dual (temperature and pH) sensitive miktoarm star copolymers of (PNIPAm)-(PLL)2 were synthesized through the combination of ATRP, ROP and click chemistry. " Propargylamine was used to initiate ROP of ZLL-NCA for the preparation of all nyl-terminated polypeptide. The use of a diazide-functional ATRP initiator afforded PNIPAm with two azide groups at the chain end. The subsequent click reaction led to the formation of a (PNIPAm)-(PZLL)2 star. The final double hydrophilic structure was obtained after deprotection of the polypeptide arms. 

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