UV-Induced Crosslinking of Poly[2-(2’-Norbornenyl)-2-Oxazoline]s

A 2-oxazoline monomer bearing a norbornenyl functionality in the side-chain was prepared from the reaction of 5-norbornene-2-carbon-itrile and 2-ethanol amine. This monomer could be successfully po-lymerized using a 2-oxazolinium-based macroinitiator that was in-situ generated from the methyl cation-initiated oligomerization of 2-ethyl-2-oxazoline. This polymer could be subjected to polymeranalogous reactions involving the alkene groups of the norbornenyl side-chains: A proof-of-concept was established by utilizing the polymers in photore-sists that were crosslinked by thiol-ene reactions involving bisfunctional thiols. Photoinitiators for the UV-induced thiol-ene reaction were re-quired in catalytic amounts only. After development, the resists exhib-ited reproduction of the geometric patterns with a resolution of 30 μm. Keywords photoresist · thiol-ene reaction · cationic polymerization · poly-mer photochemistry · poly(2-oxazoline)s · microwave-assisted polymerizatio