Grafting of Functional Monomers on Biomaterials - Biointerfaces: Where Material Meets Biology - page 314

d n 3 r 4 n g | 2

Scheme 11.1 Four methods for grafting of functional monomers on biomaterials
considered in this chapter: (A) simultaneous grafting method;
(B) peroxy/hydroxyl grafting (a two-step process); (C) grafting from a
surface using CRP (may involve an initial step of introducing a
functional group); (D) plasma polymerisation.

H O

.

O

C C O

C C O +H

H

H

Scheme 11.2 Schematic illustration of hydrogen abstraction from a polyester poly-

mer as a result of high-energy radiation.

from the grafting solution either by nitrogen degassing or by applying a vac-
uum. 8,9 This radiation process causes hydrogen (or in the absence of hydro-
gen, other element) abstraction from the polymer substrate's backbone and
formation of polymer centred radicals as illustrated for a polyester in
Scheme

11.2. These radicals can subsequently undergo graft co-

polymerisation.
The grafting process is a radical polymerisation reaction from the surface;
however, due to the continuous radiation process side reactions such as
hydrogen abstraction from the growing graft co-polymer may take place
concomitantly with the grafting process and as such branched or crosslinked
grafted chains of a broad molecular mass distribution but with well-defined