Fluorine-containing aromatic polyethers with maleimide side groups

Abstract

In this study, we carried out the first synthesis of fluorine-containing PAEs with maleimide side groups. We developed a facile and convenient method for the synthesis of such polymers by polymer-analogous reactions in PAE chains via intermediate epoxidation of initial stilbene-containing polymers. In addition, we studied the thermal transformations of the final polymers and their photochemical structuring induced by the products of photolysis of an aromatic bisazide and evaluated the corresponding systems as negative photoresists. The starting unsaturated PAEs were prepared using decafluorobiphenyl (Aldrich); 4,4'-dihydroxystilbene, which we prepared according to a reported procedure [5]; and 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (Central Glass Co., Japan). The bisphenols were introduced into the reaction mixture in a 4 : 1 molar ratio. The condensation of these monomers was carried out as recommended in a previous publication [3] in a dimethylacetamide (DMA)–benzene mixture (10 : 1 v/v) with azeotropic distillation of the evolved water and using K 2 CO 3 as the catalyst. The process was conducted at 130 ° C for 6 h under argon. The reaction took place under homogeneous conditions. The polymer thus formed was isolated by precipitation in a methanol–water mixture (3 : 1 v/v). The precipitated stilbene-containing PAE was filtered off, washed repeatedly with methanol, washed with ether, and dried in vacuum at 70 ° C. The polymer is readily soluble in amide solvents, acetonitrile, and tetrahydrofuran (THF) at room temperature. The polycondensation we carried out can be represented as follows: