Design and Synthesis of Thermally Labile Polymers for Microelectronics. Poly(vinyl tert-butyl carbonate-sulfone)

Poly(vinyl tert-butyl carbonate-sulfone) has been synthesized by using tert-butyl hydroperoxide as initiator at low temperatures. In order to optimize the reaction conditions, a series of model reactions was conducted by using vinyl acetate and sulfur dioxide. The reaction conditions for the model study were successfully applied to the copolymerization of vinyl tert-butyl carbonate and sulfur dioxide. Best results for the copolymerization were obtained by using excess liquid sulfur dioxide serving as both the solvent and the monomer. A study of the effect of temperature on the reaction showed a ceiling temperature near −20 °C under the conditions of typical experiments. Elemental and spectroscopic analyses of the poly(vinyl tert-butyl carbonate-sulfone) indicated that it had incorporated the two monomers in a 1:1 ratio and that it possessed an alternating structure. Thermal decomposition of the polymer resulted in a clean “unzipping” of both the polymer main chain and the pendant BOC groups with exclusive formation of volatile molecules carbon dioxide, acetaldehyde, isobutylene, and sulfur dioxide as confirmed both by thermogravimetric analysis (TGA) and GC mass spectroscopy.