Nonionic Surfactants for Dispersion Polymerizations in Carbon DioxideEPA Grant Number: R826115
Title: Nonionic Surfactants for Dispersion Polymerizations in Carbon Dioxide
Investigators: DeSimone, Joseph M.
Institution: University of North Carolina at Chapel Hill
EPA Project Officer: Klieforth, Barbara I
Project Period: November 1, 1997 through October 31, 2000
Project Amount: $370,000
RFA: Technology for a Sustainable Environment (1997) RFA Text | Recipients Lists
Research Category: Sustainability , Nanotechnology , Pollution Prevention/Sustainable Development
Description:More than 30 billion pounds of organic and halogenated solvents are used world-wide each year as process aids, cleaning agents and dispersants. Even when water is used in an industrial process, the large amounts of aqueous waste generated must be treated before being released in order to avoid negative environmental consequences. Solvent-intensive industries are forced to consider alternatives that will reduce or eliminate the negative impact that solvent emissions have on the environment. We have previously demonstrated that carbon dioxide in its liquid and supercritical state is an excellent environmentally benign alternative to chlorofluorocarbons (CFCS) and have shown recently that surfactant modified C02 can replace volatile organic compounds (VOCs) and water. In a variety of processes it is apparent that the widespread use of carbon dioxide by industries will depend strongly on our ability to design and synthesize efficient surfactants, amphiphilic macromolecules that act as soaps in C02 for a variety of applications. This pursuit is the main focus of this proposal.
Novel non-ionic surfactants for C02 will be prepared by a combination of anionic and controlled free radical techniques. Small angle x-ray and neutron scattering will be employed to study the micellization behavior of these materials in a C02 continuous phase. Systematic study of the kinetics of dispersion polymerizations in C02 via periodic sampling of the high pressure system will provide information that is vital to the eventual scale-up and commercialization of this technology. The design of nonionic surfactants will be based on the potential to use miscible polymer pairs as a route to prepare stable polymer colloids in C02. These surfactants will be primarily utilized for the synthesis via dispersion polymerization in C02, of a wide range of materials, starting with low Tg polymers which find use as adhesives and coatings.
By employing strategies to synthesize and utilize surfactants in CO2, we will broaden the horizon for the use of this environmentally benign solvent. This advancement will reduce the impact that the currently used VOC and CFC solvents have on human health and the environment by replacing them with C02. The large amount of contaminated aqueous waste which is currently being produced as a byproduct of plastic production will also be eliminated by using the C02-based technology proposed herein. Moreover, recent work has shown that these surfactants are highly active soaps for the removal of organic contaminants from substrates using a C02 wash. Without doubt, the use of C02 as a replacement solvent may solve many hazardous waste production and emissions problems that currently plague industry.