which raft are u use?

glass surfaces can be functionalized with trimethoxy or triethoxy silanes. If you have a SH end-group you could functionalize the surface with an ene and do thiol-ene coupling. Of course you can also do grafting-from using a silane with a RAFT agent, there are multiple examples in the literature for this.

Sehr gut, danke Mathias.

I am out of my field, as I am not a chemist.

Could you add some bibliography or protocol I may use?

I use a trithiocarboate as the RAFT agent.

For surface initiated RAFT:

http://pubs.acs.org/doi/abs/10.1021/ac0521091

http://pubs.acs.org/doi/abs/10.1021/ma900604v

A recent review about click reactions on surfaces:

http://onlinelibrary.wiley.com/doi/10.1002/admi.201500135/abstract

glass surfaces can be functionalized with trimethoxy or triethoxy silanes.