NITRATION OF DIENE POLYMERS

• Main Author: SU, BIING-HUEI DOUGLAS
• Language: ENG
• Published: ScholarWorks@UMass Amherst 1983
• Subjects: Polymers
• Online Access: https://scholarworks.umass.edu/dissertations/AAI8401009

Developing new syntheses for high energy polymers by attaching nitro groups to preformed polymers and characterizing these polymers are the objectives of this work. Our efforts have been directed toward two overall strategies. They are (a) nitromercuration followed by demercuration and (b) nitroiodination followed by dehydroiodination or deiodination. Both are illustrated below for a trans-1,4-butadiene unit. Application of the nitration method reported by Corey and Estreicher to diene polymers fails owing to the insolubility of the hydrophobic polymers in the aqueous nitromercuration reagents. Use of water immiscible organic cosolvents gives slow nitromercuration with substantial amounts of nitrate esters formed. To overcome these problems, a non-aqueous phase transfer catalyzed method for rapid selective nitromercuration of diene polymers, poly(cis-1,4-butadiene), hydroxy-terminated polybutadiene, and carboxy-terminated poly(butadiene-co-acrylonitrile), has been developed. Conducting the dinitrogen tetroxide - alkene reaction in ether in the presence of iodine has been found to produce (beta)-nitroalkyl iodides which can be transformed into either nitroalkenes or nitroalkanes easily when treated with base or reducing agent, such as sodium borohydride, respectively. The simple alkenes, cyclohexene, 1-hexene, and 2-hexene, we investigated undergo facile nitroiodination-dehydroiodination to give nitroalkenes in good yields. Hydroxy-terminated polybutadiene gives significant amounts of nitrate ester functionalities for nitroiodination in both ether and tetrahydrofuran. Reductive deiodination as well as base dehydroiodination have been studied for the nitroiodinated polymer substrates.