Grafting from Polymer Brushes and Brush-Gels

Polymer Brushes and Gels Fabricated by ‘Grafting-From’ Strategy

Hydrogel films covalently grafted on surfaces with variable thicknesses and presenting tunable properties show great promise as versatile coating materials. The precise tailoring of interfacial, mechanical and tribological properties of films would be a highly desirable asset in the design of novel systems for surface functionalization. [1,2] A novel class of hydrogel films is represented by surface-grafted polymer networks (polymer gels or covalently crosslinked brushes), which not only possess some of the characteristics of polymer brushes, but also tunable swelling and mechanical properties. Crosslinked polymer brushes can be prepared either in situ, by surface-initiated polymerization in the presence of crosslinker or, ex situ, by post-modification of presynthesized polymer brushes.

In our laboratory, we have developed a synthetic route of surface-grafted poly(acrylamide) (PAAm) films with tailored crosslink degree by using ‘grafting-from’ approach [3]. These polymer films are prepared by the UVLED surface-initiated, iniferter-mediated photopolymerization (UVLED-SIMP) on silicon surfaces. PAAm films with different crosslink degrees are fabricated by varying the concentration of crosslinker in the polymerization solution (Figure 1). Covalently crosslinked PAAm brushes are shown to be versatile and chemically stable polymeric films with highly tunable properties at a nearly constant chemical composition.