Functional block copolymer

Anionic polymerizations are well suited for the synthesis of polymers fitted at chain end with reactive functions. Block copolymers can result from reactions between suitable functions carried by two different functional precursors. In some cases the carbanionic sites themselves are the reactive functions. In other cases, functional polymers (obtained anionically, or by other methods) can be reacted with low molecular weight coupling agents. Here are a few examples ... 

Acetylene-terminated oligomers, incorporation of isoimide functionality, 462 Acid functionalities, block copolymers, 258... 

In order to achieve improved nanofabrication performance, novel functional block copolymer systems are strongly desired. Many researchers have recognized this, and novel functional systems such as metal-containing block copolymer systems have significantly simplified and improved nanofabrication processes. The combination of top-down microscale patterns with the bottom-up nanopatterns are attractive for integrating functional nanostructures into multipurpose on-chip devices. However, in order to use these materials in real-time applications, further development is still needed. More ground-shaking discoveries are needed and are also fully expected. 

Ishizu, K., Star polymers by immobilizing functional block copolymers, in (Mishra, N. K. and Kobayashi, S. (eds), Stars and Hyperbranched Polymers, Marcel Dekker, New York 1999. 

Much research has already been devoted in the past couple of years to (i) the immobilization of ATRP active metal catalysts on various supports to allow for catalyst separation and reycycling and (ii) ATRP experiments in pure water as the solvent of choice [62]. A strategy to combine these two demands with an amphiphilic block polymer has recently been presented. Two types of polymeric macroligands where the ligand was covalently linked to the amphiphilic poly(2-oxazo-line)s were prepared. In the case of ruthenium, the triphenylphosphine-functiona-lized poly(2-oxazoline)s described in section 6.2.3.2 were used, whereas in the case of copper as metal, 2,2 -bipyridine functionalized block copolymers were prepared via living cationic polymerization [63] of 2-methyl-2-oxazoline and a bipyridine-functionalized monomer as shown in Scheme 6.8. 

HYDROGEN BOND FUNCTIONALIZED BLOCK COPOLYMERS AND TELECHELIC OLIGOMERS... 

Spijker and colleagues (2005) synthesized nucleobase-functionalized block copolymers containing thymine via ATRP of a thymine methacrylate monomer from a poly(ethylene glycol) (PEG) macroinitiator. This polymer was introduced into the polymerization of an adenine containing an alkyl methacrylate... 

Figure 4.4 Formation of cylindrical aggregates via multidirectional self-association Ixmding of adenine functional block copolymers. Reprinted from Bazzi and Sleiman (2002). Copyright 2002 American Chemical Society.

Nair KP, Pollino JM, Week M. Noncovalently functionalized block copolymers possessing both hydrogen bonding and metal coordination centers. Maciomolecules 2006 39 931-940. 

Figure 5.10 Diverse applications using hydrogen bonding interactions employed by Rotello and coworkers (Arumugam et al. 2007) (a) self-assembled dendronized polymer and (b) inorganic-organic hybrid material using barbiturate functionalized nanoparticles and Hamilton wedge functionalized block copolymers.

Figure 6.7 Illustration of multipoint hydrogen bonding based self-assembly (a) hydrogen bond formation between barbituric acid functionalized gold nanoparticles and Hamilton receptor functionalized block copolymers and (b) selective deposition of nanoparticles on a microphase-separated block copolymer film. Reprinted with permission fi om Binder et al. (2005). Copyright 2005 American Chemical Society.

Adsorption of block copolymers onto a surface is another pathway for surface functionalization. Block copolymers in solution of selective solvent afford the possibility to both self-assemble and adsorb onto a surface. The adsorption behavior is governed mostly by the interaction between the polymers and the solvent, but also by the size and the conformation of the polymer chains and by the interfacial contact energy of the polymer chains with the substrate [115-119], Indeed, in a selective solvent, one of the blocks is in a good solvent it swells and does not adsorb to the surface while the other block, which is in a poor solvent, will adsorb strongly to the surface to minimize its contact with the solvent. There have been a considerable number of studies dedicated to the adsorption of block copolymers to flat or curved surfaces, including adsorption of poly(/cr/-butylstyrcnc)-ft/od -sodium poly(styrenesulfonate) onto silica surfaces [120], polystyrene-Woc -poly(acrylic acid) onto weak polyelectrolyte multilayer surfaces [121], polyethylene-Wocfc-poly(ethylene oxide) on alkanethiol-patterned gold surfaces [122], or poly(ethylene oxide)-Woc -poly(lactide) onto colloidal polystyrene particles [123],... 

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