Fig. 1.

(a) Process for inducing the thiol–ene and (meth)acrylate polymerization reactions on a surface by beam pen lithography (BPL). (i) The tip-array, coated with an ink mixture (blue) containing the probe molecules and DMPA in a polyethylene glycol (PEG) matrix, deposits the ink mixture onto thiol-terminated glass slides. (ii) Light passing through the tips of the beam pens locally exposes the patterned surface to induce homolytic cleavage of the DMPA and initiate the polymerization of the monomers within the PEG matrix. (iii) Following rinsing of the surface to remove the PEG and excess molecules, only the covalently immobilized polymers remain. Methacrylate brush polymers are shown. (b) Molecules prepared for the BPL and polymer pen lithography (PPL)-induced thiol–ene and thiol–(meth)acrylate polymerization reactions.