Polymer brushes modification

Nanoparticles phase transfer behaviors at the oil—water interface have many in common with fipid bilayer crossing behavior and the Pickering emulsion formation. The phase transfer behavior and interfacial behavior are intuitive indicators for the application potential of nanoparticle materials. Polymer brush modification enables nanoparticles to behave differendy in hydrophilic solvent, hydrophobic solvent, and their interface region. 

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. 

Amylose brushes (a layer consisting of polymer chains dangling in a solvent with one end attached to a surface is frequently referred to as a polymer brush) on spherical and planar surfaces can have several advantageous uses, such as detoxification of surfaces etc. The modification of surfaces with thin polymer films is widely used to tailor surface properties such as wettability, biocompatibility, corrosion resistance, and friction [142-144]. The advantage of polymer brushes over other surface modification methods like self-assembled monolayers is their mechanical and chemical robustness, coupled with a high degree of synthetic flexibility towards the introduction of a variety of functional groups. 

Keywords protein adsorption cell adhesion polymer brush surface modification biofouling PEO a-chymotrypsin IgG... 

The previously discussed principles of grafting-to and grafting-from can also be applied for the modification of polymer surfaces with polymer brushes. However, the binding of linkers and polymerization initiators to polymer surfaces is not as straightforward as it is for oxidic inorganic materials. Thus, dedicated pretreatments are usually necessary. These may include rather harsh reaction conditions due to the chemical inertness of many polymers (see Chapter 3). Alternatively, radiation treatment of polymers (to form radicals) followed by exposure to air may be used to form peroxides and hydroperoxides, which can be directly used as initiators for thermally or ultraviolet-induced graft polymerizations [16,17] (see Chapter 2). 

In summary, EUV activation although currently strongly dependent on access to a dedicated synchrotron beamline allows well-controlled grafting of polymer brushes from polymer surfaces with high spatial resolution capabilities. The availability of a large variety of monomers suitable for this grafting process, combined with postpolymerization modification processes, opens a wide field to introduce surface functionalities. Select examples are discussed in Chapter 4. 

Although the previously discussed methods are applicable specifically to polymer substrates, there are also strategies for surface functionalization with polymer brushes that work on a broad range of substrates. A general method that allows producing polymer brushes on silicon, gold, perfluorinated poly(ethylene-co-propylene), and poly (styrene) has been recently introduced [21]. The first step of the modification sequence was not sensitive to the substrate used. An... 

Neuhaus S, Padeste C, Spencer ND. Versatile wettabiUty gradients prepared by chemical modification of polymer brushes on polymer foils. Langmuir 2011 27(11) 6855—61. 

Duebner M, Spencer ND, Padeste C. Light-responsive polymer surfaces via postpolymerization modification of grafted polymer-brush structures. Langmuir 2014 30(49) ... 

A special part of this chapter is the modification of surfaces with hb polymer brushes that are typically anchored by one end of the polymer chain. This is only a short insight into this area detailed information can be found in a review article. " For an hb structure one could also modify the multiple end groups statistically with more than one anchoring group in this manner Haag and co-workers prepared hbPG on gold surfaces... 

Recently, surface modification techniques for polymer chains have progressed a great deal with the development of a new polymer synthesis method. In particular, surface-initiated atom transfer radical polymerization (SI-ATRP) is one of the most effective modification methods for preparing a well-defined dense polymer brush structure, or polymer brush, on solid substrates. Thus, a self-oscillating polymer brush prepared by SI-ATRP can be expected to create a novel self-oscillating surface with autonomous function, which will lead to potential applications in transporting systems for nanomaterials of flow control in microfluidics. 

The brush-gel polymer film is a submicrometer particulate layer with cross-linked polymer brushes. Nonporous particles with diameter of 350 nm, 700 nm, or 900 nm, modified with polyacrylamide, were applied on a silicon wafer as slurry to obtain a 15-pm thin layer. Coating with polyacrylamide brushes increased the capillary force for increased mobile-phase velocity and the overall separation performance. Three fluorescence-labeled proteins were separated with a sinapinic acid containing mobile phase for subsequent detection via MALDl [35], A second modification of this brush-gel polymer was manufactured by cross-linking poly(glycidyl methacrylate) and di(ethylene glycole)dimethacrylate to graft the thin layer covalently on the glass substrate and to manipulate the separation characteristic. The separation of a fluorescent dye mixture was performed on this layer and the ability for a multiple reuse was shown [36]. 

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