Environmentally Benign Formation of Poly(methacrylate ester) Microspheres by Precipitation Copolymerization in Supercritical Carbon Dioxide

2003 ◽  
Vol 36 (4) ◽  
pp. 516-521 ◽  
Author(s):  
Kiyoshi Matsuyama ◽  
Kenji Mishima ◽  
Keiji Takahashi ◽  
Ryugen Ohdate ◽  
Hajime Tomokage
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Environmentally Benign ◽  
Supercritical Carbon

Study on the Graft Copolymerization of AN onto PP by Using Supercritical Carbon Dioxide

2013 ◽  
Vol 815 ◽  
pp. 717-721 ◽  
Author(s):  
Ya Zhen Wang ◽  
Di Ma ◽  
Cheng E Yue ◽  
Wei Nan Jia ◽  
Yong Li
Keyword(s):  
Carbon Dioxide ◽  
Reaction Time ◽  
Solid State ◽  
Supercritical Carbon Dioxide ◽  
Graft Copolymerization ◽  
Environmentally Benign ◽  
Graft Polymer ◽  
Swelling Agent ◽  
Grafting Reaction ◽  
Supercritical Carbon

The research reported in this paper aimed at exploring the advantages of using supercritical carbon dioxide (scCO2) as an environmentally benign solvent and swelling agent for carrying out the grafting process of acrylonitrile (AN) onto polypropylene (PP) in the solid state by using benzoyl peroxide (BPO) as initiator in the reaction. In order to get a well graft ratio, the effects of various factors in this grafting reaction are investigated. Those factors included the reaction time, reaction temperature, monomer and initiator concentrations and the CO2 pressure. IR was used to characterize the constituent of the graft polymer. Then anti-aging of the PP-g-AN was studied by UV-vis. Results showed that the scCO2-assisted solid-state grafting process of AN onto PP did have some scientifically interesting and industrially relevant advantages over the melt process. Compare with virgin PP, the graft polymer have a better performance in anti-aging.

Free-Radical Chemistry in Supercritical Carbon Dioxide

2004 ◽  
Author(s):  
J. M. Tanko
Keyword(s):  
Carbon Dioxide ◽  
Free Radical ◽  
Supercritical Carbon Dioxide ◽  
Green Chemistry ◽  
Chemical Reactions ◽  
Environmentally Benign ◽  
Supercritical State ◽  
Liquid Phases ◽  
Temperature And Pressure ◽  
Supercritical Carbon

During the 1990s, the chemical industry has focused on ways to reduce and prevent pollution caused by chemical synthesis and manufacturing. The goal of this approach is to modify existing reaction conditions and/or to develop new chemistries that do not require the use of toxic reagents or solvents, or that do not produce toxic by-products. The terms “environmentally benign synthesis and processing” and “green chemistry” have been coined to describe this approach where the environmental impact of a process is as important an issue as reaction yield, efficiency, or cost. Most chemical reactions require the use of a solvent that may serve several functions in a reaction: for example, ensuring homogeneity of the reactants, facilitating heat transfer, extraction of a product (or by-product), or product purification via chromatography. However, because the solvent is only indirectly involved in a reaction (i.e., it is not consumed), its disposal becomes an important issue. Thus, one obvious approach to “green chemistry” is to identify alternative solvents that are nontoxic and/or environmentally benign. Supercritical carbon dioxide (sc CO2) has been identified as a solvent that may be a viable alternative to solvents such as CCl4, benzene, and chloroflurocarbons (CFCs), which are either toxic or damaging to the environment. The critical state is achieved when a substance is taken above its critical temperature and pressure (Tc, Pc). Above this point on a phase diagram, the gas and liquid phases become indistinguishable. The physical properties of the supercritical state (e.g., density, viscosity, solubility parameter, etc.) are intermediate between those of a gas and a liquid, and vary considerably as a function of temperature and pressure. The interest in sc CO2 specifically is related to the fact that CO2 is nontoxic and naturally occurring. The critical parameters of CO2 are moderate (Tc = 31 °C, Pc = 74 bar), which means that the supercritical state can be achieved without a disproportionate expenditure of energy. For these two reasons, there is a great deal of interest in sc CO2 as a solvent for chemical reactions. This chapter reviews the literature pertaining to free-radical reactions in sc CO2 solvent.

Preparation of Semi-Conducting Polymeric Nanoparticles by Supercritical Carbon Dioxide RESOLV Process

2008 ◽  
Vol 8 (9) ◽  
pp. 4707-4710 ◽  
Author(s):  
Hullathy Subban Ganapathy ◽  
Jun Ho Kim ◽  
Seung-Soo Hong ◽  
Kwon Taek Lim
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Polymeric Nanoparticles ◽  
High Surface ◽  
Sodium Dodecyl ◽  
Rapid Expansion ◽  
Environmentally Benign ◽  
Spherical Nanoparticles ◽  
Average Size ◽  
Supercritical Carbon

The rapid expansion of supercritical carbon dioxide solutions into a liquid solvent (RESOLV) technique with environmentally benign supercritical carbon dioxide was used to produce semi-conducting polymeric nanoparticles of fluoroalkyl ester substituted thiophenes. When the supercritical solutions of the conjugated polymer, poly[2-(3-thienyl) acetyl-3,3,4,4,5,5,6,6,7,7,8,8,8, tridecafluoro-1-octanate] (PSFTE) were expanded into aqueous solutions through a small capillarynozzle (150 μm), spherical nanoparticles in the range of 50–100 nm were obtained. However, after 15 min of expansion, the particles tended to aggregate to form larger objects due to the high surface energy of the polymeric nanoparticles. In order to prevent the agglomeration of particles, a relatively low concentration of sodium dodecyl sulphate (SDS) or NaCl was used as a stabilizing agent in aqueous solution. While NaCl did not give enough stabilization to the system, uniform spherical nanoparticles of PSFTE having an average size of 45 nm were successfully obtained by SDS stabilization.

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