Brushes conformation changes

The chain dimension in the height direction was evaluated as the thickness of the brush layer, I, relative to the chain contour length, io, by atomic force microscopy (AFM). Figure 4.10 shows the solvent dependence of the conformation of the PMMA brush. Whereas the brush chain changes its conformation in response to the solvent quality at the low graft density, the high-density PMMA brush does not show... 

Fig. 18 Schematic of the conformational changes from mushroom to brush state that occur in graft-polymerized PDMAm during the chain propagation process...

Peerce, B.E. Wright, E.M. (1984). Sodium-induced conformational changes in the glucose transporter of intestinal brush borders. J. Biol. Chem. 259, 14105-14112. 

Figure 37 Brush molecules change from (a) flexible to (b) rod-like conformation with the increase in the DP of side chains n. (c) Persistence length Ip is determined as the distance along the chain at which the fractal dimension changes from d= 1 to d= 1.33. (d) The persistence length increases with the side-chain length as Ip Reprinted from Sheiko, S. S. Sun, F. C. Randall, A. etal. /Vafwre 2006, 44( (7081), 191-194, with permission from Nature...

Unlike conformation transition of brushes in solution, conformational changes of adsorbed molecules driven by exposure to different kinds of solvents are particularly interesting due to the possibility of both in situ imaging and manipulation of the conformational properties of molecular bmshes. Environment-controlled AFM was used to in situ... 

Figure 75 Conformational changes of brush-like macromolecules with PnBA side chains during their spreading on a mica substrate, as monitored by AFM. (a) The flowing molecules become more extended with increasing distance (/) from the drop center and occupy a larger area per molecule during spreading, (b) After calibration of the molecular area, the gradient of the film pressure n(/) driving flow was obtained. Reprinted from Xu, H. Sun, F. C. Shirvanyants, D. G. etal. Adv. Mater. 2007, 79(19), 2930-2934, with permission from Wiley-VCH. ...

FIGURE 12.8 Reversible pH-controlled transformation of the redox-polymer brush (P4VP-Os complex) grafted to an ITO electrode between its electrochemically active and inactive states. The conformational changes of P4VP regulate the activation (pH = 4) or inhibition (pH = 6) of the electron transfer from GOx to the electrode support leading to the reversible... 

Figure 5.4 Schematic illustration of conformational changes of polymer brushes of (a) homopolymers and (b) mixed polymer brushes. Furthermore, the schematic structure of (c) block copolymers and (d) branched polymer brushes is shown.

Figure 5.6 (a) Schematic illustration of conformation changes of a pH-responsive polymer brush, (b) Response of a poly(methacrylic acid) brush (11 lun thick) modified quartz crystal... 

Figure 5.7 Schematic illustration of conformation changes of an ionic strength-responsive polymer brush.

Lee, H.-L, Boyce, J. R., Nese, A., Sheiko, S. S., Matyjaszewski, K. (2008). pH-indnced conformational changes of loosely grafted molecular brushes containing poly(acrylic acid) side chains. Polymer, 49, 5490-5496. 

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