Polymer brashes

For polyelectrolyte brashes, the chain conformation is governed by the electrostatic interactions between the charged monomer units [56]. At high pH, the amine groups of the polymer chains are deprotonated, and the polymer is considered to be neutral. As a result, the polymer chains tend to attain a collapsed conformation due to the hydrophobic interactions, and the diffusion of the positively charged Ru(NH3)6 is not sterically hindered by the polymer brash, nor is it repelled electrostatically. In contrast, at low pH, the polymer brash becomes protonated and stretches away from the surface as a result of electrostatic repulsions between the charged monomer units and between the polymer chains. The diffusion of Ru(NH3)6 + in this case is blocked as a result of both electrostatic repulsion from the positively charged polymer chains and as a result of the steric hindrance. 

Takahashi, H. Matsuzaka, N. Nakayama, M. Kikuchi, A. Yamato, M. Okano, T. Terminally fnnctionalized thermoresponsive polymer brashes for simultaneously promoting cell adhesion and ceU sheet harvest. Biomacromolecules 2012,13, 253-260. 

Zhao B, Brittain WJ (2000) Polymer brashes surface-immobilized macromolecules. Prog Polym Sci 25 677-710... 

Recent advances in controlled synthesis of macromolecules, in particular in coti-troUed radical polymerization, have allowed the cmistraction of polymers with various topologies and compositions. Successful design of star-shaped polymers, molecular polymer brashes, and amphiphilic block copolymers and terpolymers has... 

A mnch more recent development, however, is the drive to create responsive polymer brashes (Chen et al., 2010 Stuart et al 2010). These brushes respond with certain behavior, such as swelling, collapsing, charging to an external trigger, and allowing... 

In a sense, all polymer brashes are responsive to solvent. For example, a simple PEO polymer brush will swell in water, but will be collapsed when exposed to an apo-lar solvent such as hexane. StiU, what we discuss here as solvent-resistant brashes... 

It is clear that there is a bright future for responsive polymer brashes in the field of biomedical applications. They provide a unique control over surfaces that is difficult to match by any other surface coating. They have been shown be able to control wettability, cell adhesion, bacterial adhesion, and protein adsorption, which provide many opportunities for functional coatings of medical implants, protein carriers, biosensors. 

Nguyen, A. T., Baggerman, J., Paulusse, J. M. J., Zuilhof, H., Van Rijn, C. J. M. (2011). Bioconjugation of protein-repellent zwitterionic polymer brashes grafted from silicon nitride. Langmuir, 28, 604—610. 

Xu, L. Q., Wan, D., Gong, H. F., Neoh, K.-G., Kang, E.-T., Fu, G. D. (2010). One-pot preparation of ferrocene-fnnctionabzed polymer brashes on gold substrates by combined surface-initiated atom Transfer radical polymerization and Click chemistry . Langmuir, 26, 15376-15382. 

Thermosensitive, and amphiphilic polymer bmshes optically active polymers consist of helical poly(iV-propargylamide) main chains and thermosensitive poly(iV-iso-propylacrylamide) (PNlPAm) side chains, were prepared via a novel methodology combining catalytic polymerization, atom transfer radical polymerization (ATRP), and click chemistry. The characterization of GPC, FT-IR, and H-NMR measurements indicated the successful synthesis of the novel amphiphilic polymer brashes. For the confirmation of helical structure of the polymers backbones and the optical activity of the final brashes used UV-Vis and CD spectra. The polymer with optically active cores (helical polyacetylenes) and thermosensitive shells (PNlPAm) brashes self-assembled in aqueous solution forming core/shell structured nanoparticles [137]. 

Even more interesting electrochemical properties were discovered for the polymer brash tethered to an electrode surface and functionalized with bound redox species [30]. Os(dmo-bpy)2 (dmo-bpy = 4,4 -dimethoxy-2,2 -bipyridine) redox groups were covalently bound to the P4VP brash chains grafted on an ITO electrode. The polymer-bound redox species were found to be electrochemically active at pH <5 when the polymer is... 

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