Kinetics of grafted chains in polymer brushes

GAO AND OU-YANG Kinetics of Grafted Chains in Polymer Brushes... 

The preparation of polymer brushes by controlled radical polymerization from appropriately functionalized polymer chains, surfaces or particles by a grafting from approach has recently attracted a lot of attention.742 743 The advantages of growing a polymer brush directly on a surface include well-defined grafts, when the polymerization kinetics exhibit living character, and stability due to covalent attachment of the polymer chains to the surface. Most work has used ATRP or NMP, though papers on the use of RAFT polymerization in this context also have begun to appear. 

Class D. The class of engineered assemblies includes systems that do not spontaneously form ordered structures under normal conditions. Their classification as SPs can be justified since elements of supramolecular interaction stfil assist the final organization. Some examples are layered assembly of complementary poly electrolytes obtained by stepwise deposition under kinetic control (cf. Chapter 19), and polymer brushes prepared by grafting a polymer chain over a SAM of an initiator [6]. Both approaches allow a fine-tuning of surface properties and patterning possibilities. Tailored performance in applications, such as biocompatibility, biocatalysis, integrated optics and electronics have been considered. Additional differences between self-assembled and engineered SPs are discussed in Section I.C. 

Molecules grafted to PDMS surface, due to the kinetic hindrance from the grafted chains against the new coming species, usually form brushes of low density. The film thickness is limited by the size of grafted molecule and it can have defects in surface uniformity. In grafting from technique the polymerization starts from the active initiation sites located on the modified surface. The growing species do not suffer from molecular hindrance and a dense layer of polymer chains can be formed. 

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