Fundamental Principles of Polymeric Materials by Brazel Christopher S.; Rosen Stephen L.; & Stephen L. Rosen

Author:Brazel, Christopher S.; Rosen, Stephen L.; & Stephen L. Rosen
Language: eng
Format: epub
Publisher: Wiley
Published: 2012-04-24T16:00:00+00:00

10.8 Grafted Polymer Surfaces

Grafting a polymer onto a surface is a great way to change the surface properties of a material. This can be done to improve the compatibility between layers in a composite material, to reduce surface fouling, or to improve biocompatibility (among many potential applications). Because living polymerizations can be used for good control of polymer properties, they are often used in graft polymerizations.

The grafting method normally follows one of two patterns (Figure 10.5): grafting to or grafting from. In the first method, oligomers or polymers are pre made (and can easily be characterized for molecular weight and polydispersity) and attached to a surface through any number of chemistries (several condensation reactions can be used here). In grafting from method, the surface must be activated (i.e., form a free-radical or growing living polymer complex) through which monomer can add. In this second technique, the grafts are more difficult to analyze, since the molecular weight and polydispersity cannot be determined without destroying the surface (or at least removing the grafts). Although this drawback may seem to favor grafting to techniques, a balancing disadvantage of the grafting to technique is that the large oligomers or polymers may have significant steric hindrances or diffusive resistance in reaching the surface for binding. This results in a surface that has a lower graft coverage (graft density). Grafting techniques are discussed further by Bhattarcharya and Misra [25].

Figure 10.5 Depiction of methods to form a surface grafted with polymers. (a) Grafting from a surface by growing a polymer chain from surface functional groups (F). (b) Grafting to a surface by attaching a premade polymer to functional groups (F) on the surface.

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