Formation of Phenoxynorbornane Pendant Groups by Acid-Catalyzed Hydroalkoxylation of Poly(hydroxystyrene) and Its Application to Photopatterning.

Poly(hydroxystyrene) (PHS) reacts with norbornene in the presence of acid to form a phenoxynorbornane pendent group through the hydroalkoxylation of the norbornene double bond by the phenol -OH group of PHS. Films of PHS, an aqueous base soluble polymer, containing norbornene derivatives and a photoacid generator (PAG) create a negative tone photopatternable composition. Acid generated in the exposed regions of the film promotes the hydroalkoxylation reaction generating the phenoxynorbornane pendent group, rendering the film insoluble in an aqueous base developer. Both dinorbornene and mononorbornene-functional additives were evaluated. In the case of the mononorbornene additive, a unique example of a negative tone photopatterned film that can be reworked after patterning by dissolution in a mild solvent at room temperature was demonstrated. Polymers containing aliphatic alcohol and carboxylic acid pendant functionalities could be photopatterned in the presence of dinorbornene additives showing the generality of this method.