Fundamental Studies of Molecular Interactions and Dissolution Inhibition in Poly(norbornene-alt-maleic anhydride)-Based Resins

The progress of developer base into films of terpolymers of norbornene−maleic anhydride and acrylic acid was shown to be a percolation process with a critical site concentration of x(c) = 0.084, implying that every acrylic acid site in the terpolymer makes 12 monomer units of the polymer water compatible. Using these terpolymers, the dissolution inhibition mechanism for two types of common additives, tert-butyl carboxylate (e.g., cholates, cyclohexanecarboxylates, and malonates) dissolution inhibititors and onium salt photoacid generators (PAG's), were examined. Additionally, the dissolution promotion mechanism of carboxylic acids released from acidolysis of tert-butyl esters was investigated. For a wide range of cholates and other tert-butyl carboxylate derivatives, increasing hydrophobicity is a good predictor of increased dissolution inhibition. The molar dissolution promotion ability of a carboxylic acid increases with increasing number of both carboxyl and hydroxyl ester functional groups. For onium salt PAG's, a decrease in dissolution inhibition occurred when increasing the hydrophobicity and size of counteranions. Rather than being tied to hydrophobicity, large changes of dissolution inhibition in this class of materials appear to correlate with their ability to interact with carboxyl groups.