Solvency-induced Conformational Change of PNIPAM Brushes

4 Solvency-induced Conformational Change of PNIPAM Brushes 

PNIPAM not only has the thermosensitive property, but also exhibits a reentrant behavior or cononsolvency in response to the composition of a mixed solvent consisting of water and a water-miscible organic solvent [35]. That is, PNIPAM is soluble in either water or organic solvent but precipitant in their mixture with a certain composition. Several models have been proposed to explain the reentrant 

In comparison with the synthetic polyelectrolytes, studies on the conformational change of biopolyelectrolytes (e.g., DNA) have more important implications 

The folding of DNA chains can be viewed in terms of AD versus —Af relation (Fig. 2.15). The folding of DNA chains with a low grafting density only involves one kinetic process. This is because the space around DNA chains is enough for their full folding. However, two kinetic processes are observed in the folding of 

DNA with a high grafting density. As discussed above, the DNA chains are expected to partially fold in the hrst process. In the second process, the DNA chains have to rearrange themselves to have more space for further folding. 

---