Synthesis and characterization of new photoresponsive acrylamide polymers having pendant chalcone moieties

New acrylamide monomers, 4-acrylamidophenyl-2′,3′-benzostyryl ketone (APBSK) and 4-acrylamidophenyl-4′-N,N′-dimethylstyryl ketone (APDSK) having a free-radical polymerizable group and a photocrosslinkable functional group, were synthesized by reacting the corresponding aminochalcones with acryloyl chloride in the presence of triethyl amine. The monomers were polymerized in methyl ethyl ketone at 70 °C using benzoyl peroxide as the initiator. The resulting polymers were characterized by UV, IR, 1H NMR and 13C NMR spectroscopy. The polymers were found to be soluble in several polar aprotic solvents and in chlorinated solvents but insoluble in aliphatic and aromatic hydrocarbons and in alcohols. The molecular weight data of the polymers as obtained from gel permeation chromatography suggests a higher tendency for chain termination by dimerization than disproportionation. The glass transition temperature of the polymers was determined by differential scanning calorimetry. Thermogravimetric analysis of the polymers carried out in air reveals that the polymers possess good thermal and thermo-oxidative stability required of a negative photoresist. The photosensitivity of the polymer was investigated in various solvents in the presence and absence of triplet photosensitizers. The effect of the different solvents and concentration on the rate of photocrosslinking of the polymers were also examined for using the polymers as negative photoresist materials.