Brush surface-initiated polymerization

Wang, D., et al., Graphene functionalized with azo polymer brushes Surface-initiated polymerization andphotoresponsiveproperties. Advanced Materials, 2011. 23(9) p. 1122-1125. 

Wang, D. Ye, G. Wang, X. Wang, X. (2011). Graphene Functionalized with Azo Polymer Brushes Surface-Initiated Polymerization and Photoresponsive Properties. Adv. Mater., 2011 (DOI 10.1002/adma.201003653). 

Hoven et al. [34] used a chemically grafted tris(trimethylsiloxy)silyl (tris(TMS)) monolayer on a silicon oxide substrate as a template for creating nanoclusters of polymer brushes. Surface-initiated polymerization of 2-meth-acryloyloxyethyl phosphorylcholine (MFC) and tert-butyl methacrylate (t-BMA) was used to generate polymer brushes via ATRP from a-bromoester groups tethered to the residual silanol groups on the silicon surface, as... 

Wang J, Gibson MI, Barbey R, Xiao SJ, Klok HA (2009) Nonfouling polypeptide brushes via surface-initiated polymerization of N-epsilon-oligo(ethylene glycol)succinate-L-lysine N-carboxyanhydride. Macromol Rapid Commun 30 845-850... 

Fig. 9.19 Preparation of polymer brushes on solid surfaces by a) chemical grafting of end-functionalized linear polymers or selective adsorption of asymmetric block copolymers and b) by surface-initiated polymerization (SIP) using initiator functions on the solid surface. The depicted SAM bearing to-functionalities...

In this method, a reactive group on the surface initiates the polymerization, and the propagating polymer chain grows from the surface (Fig. 9.19b). In principle, it can be employed with all polymerization types, and a number of papers have reported high amounts of immobihzed polymer using surface-initiated polymerization with various initiator/monomer systems. If controlled or Hving polymerization techniques are used, block copolymer or end-functionahzed polymer brush systems can be prepared in consecutive reaction steps (Fig. 9.19c). 

The first report on living carbocationic surface-initiated polymerization (LCSIP) using a defined surface modification is by Vidal and Kennedy [268-270]. They prepared poly(isobutene) (PIB) brushes from silica surfaces using a silane functionalized benzylchloride activated by a Lewis acid. 

The same aplies to polymer brushes. The use of SAMs as initiator systems for surface-initiated polymerization results in defined polymer brushes of known composition and morphology. The different polymerization techniques, from free radical to living ionic polymerizations and especially the recently developed controlled radical polymerization allows reproducible synthesis of strictly linear, hy-perbranched, dentritic or cross-linked polymer layer structures on solids. The added flexibility and functionality results in robust grafted supports with higher capacity and improved accessibility of surface functions. The collective and fast response of such layers could be used for the design of polymer-bonded catalytic systems with controllable activity. 

Advincula R. Polymer Brushes by Anionic and Cationic Surface-Initiated Polymerization (SIP). Vol. 197, pp. 107-136. 

Fig. 10 Illustrations of the microchannel confined surface-initiated polymerization (p-SIP) route for producing gradient polymer brush libraries a route for making polymer molecular weight and block copolymer libraries b route for making statistical copolymer libraries. Red arrows show the flow of monomer solution from a syringe pump used to gradually fill the microchannel. See text for details...

In general, in the field of materials or condensed matter, the preparation of polymer brushes on solid surfaces is of great interest for surface modification and composite material preparation [4-6]. A number of model surface grafting techniques have been used on planar surfaces and particles and have been the subject of previous reviews. While a munber of polymer brush preparation methods have been reported using physisorption or chemisorption or so-called grafting onto methods, the emphasis of this review is on surface-initiated polymerization (SIP) methods or grafting from methods. 

A dense polymer brush is obtained using the grafting from techniques. Surface-initiated polymerization in conjunction with a living polymerization technique is one of the most useful synthetic routes for the precise design and functionalization of the surfaces of various solid materials with well-defined polymers and copolymers. Above all, surface-initiated living radical polymerization (LRP) is particularly promising due to its simplicity and versatility and it has been applied for the synthesis of Au NPs. 

In one example polymer segment density profiles of weak polyacid brushes consisting of polymethacrylic acid (PMAA) chains were investigated as a function of the pH of the environment by means of multiple-angle ellipsom-etry [68]. The polymer brushes were prepared by surface-initiated polymerization of methylacrylic acid as described above. 

Figure 6. Interaction of a water droplet with 200 micron features of a patterned polymer brush prepared by surface-initiated polymerization. The unusual wetting profile is due to preferential interaction of the water droplet with the polymery lie acid) brush domains (light) and complete non-wetting of the hydrophobic poly(tert-butyl acrylate) domains (dark).

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