Polymer brushes self-assembled monolayers

Senaratne, W., Andruzzi, L. and Ober, C. K. (2005) Self-assembled monolayers and polymer brushes in biotechnology Current applications and future perspectives. Biomacromolecules, 6, 2427-2448. 

In the second part of this Chapter the thickness of the organic layer under discussion is slightly increased and a closer look at recent developments of more complex surface-bonded systems involving polymers is outlined. Despite the introduction of flexible polymer chains, the surface coating should still be defined and uncontrolled heterogeneities minimized. Here, especially, polymer brush-type layers where self-assembled monolayers (SAMs) are used as two-dimensional template systems for the preparation of well-defined surface coatings will be subject of a more detailed discussion. 

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. 

Fig. 58 Schematic of inferred structure for CdSe nanocrystal infiltrated polymer brush photovoltaic device. From bottom to top ITO-coated glass slide modified by surface attachment of a bromine end-capped trichlorosilane self-assembled monolayer (SAM) (squares) polymer brushes grown from the SAM (lines) CdSe nanocrystals infiltrated into the brush network exhibiting some degree of phase separation in the plane of the film (small circles) and an aluminum cathode cap. (Reprinted with permission from [256], 2005, American Chemical Society)...

In order to vary the surface properties of electronic materials, coatings need to be applied such that the interaction with the surface is optimized to a very fine degree. There are two ways to achieve this one using short chains which naturally form self-assembled monolayers (SAMs), the other building long chain molecules which bind to the surface at several points to form polymer brushes, as shown in Fig. 13.17. °... 

Thermoresponsive polymer brushes on 20 nm colloidal gold formed through ATRP of W-isopropyl acrylamide in aqueous media End-functionalized 3D self-assembled monolayers (SAMs) on GNPs by living cationic ring-opening polymerization reaction directly on GNP surfaces... 

Surface-chemical gradients are mainly prepared via two systems self-assembled monolayers (SAMs) or polymer coatings, especially brush-like polymer coatings—Table 1 provides an overview of the different preparation methods for the generation of surface-chemical gradients and the applications for which they have been used. 

Like a bulk responsive material, surface of a substrate can be responsive upon electrochemical, photo, temperature, pH, mechanical, or electrical stimuli (Lahann Langer, 2005). Researchers are developing different ways to make these smart surfaces such as self-assembled monolayers (SAMs), polymer brushes, or copolymer coatings. A classic example is a switchable SAM surface in responsive to electric potential, which achieve hydrophobic-hydrophilic transition on a gold substrate. The switchable surfaces provide an idea platform to smdy surface-biological system interactions (Lahann et al., 2003). Polymer brushes and copolymers are more practical avenues to be applied with long-term performance. 

Xue et al. have investigated the effect of graft PIPAAm brnsh density on the resulting cell adhesion character in terms of the number and occnpied area of adhered cells, and the circularity of the cells, and they find the correlation of the polymer graft density with cell attachment and detachment character (Choi et al., 2012 Xue et al., 2012). They prepare TRCS on a self-assembled monolayer formed silicon surface, where various polymer densities are grafted by using surfaces initiated ATRP method. On TRCS with a dense polymer brush (0.11 chains/nm ), a lower circularity is found in attached cells having an extremely poor cell adhesive character. When the polymer... 

Farhan et al. [25] reported surface-initiated polymerizations from polymeric surfaces of commercially important polyester films, poly(ethylene terephthalate) (PET), and poly(ethylene naphthalate) (PEN). Patterned self-assembled monolayers (SAMs) of the trichlorosilane initiator were first immobilized on the surface through a soft lithographic method of microcontact printing (ICP). Grafting from the surface was initiated via controlled ATRP, under aqueous conditions, to create patterned brushes of the ther-moresponsive polymer poly(N-isopropylacrylamide) (PNIPAm), as shown in Figure 1.8. 

Raynor, J. E., Capadona, J. R., CoUard, D. M., Petrie, T. A., and Garcia A. J. 2009. Polymer brushes and self-assembled monolayers versatile platforms to control cell adhesion to biomaterials. Biointerphases 4 FA3-FA16. 

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