Other

North Carolina State University

The University of North Carolina at Chapel Hill

The University of Western Ontario

Paul A Charpentier

Joseph Desimone

George W Roberts

Kevin D Burgess

Xinsheng Li

The present invention provides two methods for synthesizing novel titania-polyurethane (nTiO-PU) nanocomposites for self-cleaning coatings, one a polymer functionalization method ('grafting to') and the other, a monomer functionalization method ('grafting from'). Here, 2,2 bis(hydroxymethyl) propionic acid (HMPA) was used as the coordination agent, which was reacted with n-TiO(50:50 anatase/rutile) to form nTiO-HMPA, then polymerized in the monomer functionalization method. In the polymer functionalization method, HMPA was reacted with a pre-polymer to form the PU, and then subsequently reacted with n-TiOto form the polymer nanocomposite. The photocatalytic cleanability of the nanocomposites was investigated when exposed to ultraviolet radiation using additional unreacted HMPA or stearic acid as the model &#x201c;dirt&#x201d; compounds. Nanocomposites prepared using both strategies showed similar self-cleaning behavior, although the monomer technique gave less substrate degradation.

Self-cleaning coatings

A one step synthetic route of polymeric compositions of a polyolefin and inorganic network consisting of components selected from Si, Zr, Ti, is disclosed. The synthetic route combines parallel reactions of free radical polymerization to form polymer, and hydrolysis of either Si, or Zr, or Ti or both of them precursors. The network consisting of Si, Zr, Ti, is chemically bonded to or within the polymer matrix. The inorganic or organic molecules can then be polymerized under conditions effective to cause the polymerized inorganic or organic molecules into macromolecular networks. The compositions of the polymeric composites can be easily controlled by adjusting the reactant ratio and reaction rate or conditions such as temperature and pressure, wherein the inorganic compositions disperse in nanoscale within polymeric composites when their concentrations fall below moderate levels. A novel synthesis route for making polymer composites and/or polymer nanocomposites of a polyolefin and an inorganic network consisting of components selected from Si, Zr, Ti, is disclosed. The synthesis route comprises hydrolysis of either Si, or Zr, or Ti alkoxides or mixtures of these precursors within a polymer matrix in supercritical fluids.

Polymer composite synthesis in supercritical fluids

A method for carrying out the continuous polymerization of a monomer in a carbon dioxide reaction medium comprises the steps of: (a) providing an apparatus including a continuous reaction vessel and a separator; (b) carrying out a polymerization reaction in the reaction vessel by combining a monomer and a carbon dioxide reaction medium therein (and preferably by also combining an initiator therein), wherein the reaction medium is a liquid or supercritical fluid, and wherein the reaction produces a solid polymer product in the reaction vessel; then (c) withdrawing a continuous effluent stream from the reaction vessel during the polymerization reaction, wherein the effluent stream is maintained as a liquid or supercritical fluid; then (d) passing the continuous effluent stream through the separator and separating the solid polymer therefrom while maintaining at least a portion of the effluent stream as a liquid or supercritical fluid; and then (e) returning at least a portion of the continuous effluent stream to the reaction vessel while maintaining the effluent stream as a liquid or supercritical fluid. The need for significant recompression of the continuous effluent stream prior to return to the reaction vessel is thereby minimized. Apparatus for carrying out such methods is also disclosed.

Apparatus for continuous production of polymers in carbon dioxide

Continuous process for making polymers in carbon dioxide

A method for forming a fluoropolymer comprises providing a reaction mixture comprising carbon dioxide, at least one fluoromonomer, and an initiator; and reacting the at least one fluoromonomer in the reaction mixture to form a fluoropolymer. The fluoropolymer has a multimodal molecular weight distribution.

Growing community of inventors

London, Canada

Paul A Charpentier