Copolymerization of Elemental Sulfur and Functional Styrenics

This invention relates to polymeric compositions. In particular, the attractive chemical accessibility and functional diversity of styrenic comonomers used with elemental sulfur to prepare a new chemical platform for sulfur-based polymeric materials and to further enable post-polymerization modifications for improving the properties of sulfur-based materials. 

Background: 
An incredible abundance of elemental sulfur, nearly 7-million tons is generated as a waste byproduct from hydrodesulfurization of crude petroleum feedstocks, which converts alkanethiols and other (organo) sulfur compounds into S8. Before the invention of the inverse vulcanization process, there were only a limited number of synthetic methods available to utilize and modify elemental sulfur. Current industrial utilization of elemental sulfur is centered around sulfuric acid, agrochemicals, and vulcanization of rubber. For example, elemental sulfur is used primarily for sulfuric acid and ammonium phosphate fertilizers, where the rest of the excess sulfur is stored as megaton-sized, above ground sulfur towers. While sulfur feedstocks are plentiful, sulfur is difficult to process. In its original form, elemental sulfur consists of a cyclic molecule having the chemical formulation S8. Elemental sulfur is a brittle, intractable, crystalline solid having poor solid-state mechanical properties, poor solution processing characteristics, and there is a limited slate of synthetic methodologies developed for it. Hence, there is a need for the production of new materials that offers significant environmental and public health benefits to mitigate the storage of excess sulfur in powder, or brick form.

Applications:

• A wide range of functional sulfur-styrenic polymer materials can be prepared by direct copolymerization of a styrenic comonomer with sulfur, or post-polymerization modification of the sulfur-styrenic polymer with other monomers (e.g., aniline, epoxides, isocyanates)
• Improved battery technology with materials with extended cycle lifetimes while retaining reasonable charge capacity enable more competitive transportation and energy storage applications

Advantages:

• Using elemental sulfur feedstocks for polymer materials reduces cost and improves sustainability
• Styrene and styrenic derivatives are inexpensive and widely available