Title: FLEXIBLE TO RIGID NANOPOROUS POLYURETHANE-ACRYLATE (PUAC) TYPE MATERIALS FOR STRUCTURAL AND THERMAL INSULATION APPLICATIONS

 Number/Link:US2015/0266983

Applicant/Assignee: University of Missouri

Publication date: 24-09-2015

“Gist”: A trifunctional acrylate-ended urethane monomer is polymerized in solvent and supercritically dried

Why it is interesting: Research related to nanoporous materials has been gaining significant momentum in recent years and both inorganic (usually silica-based) and organic (e.g resorcinol-formaldehyde or polyurethane -based) aerogels are increasingly being used especially for thermal insulation applications. The current invention relates to hybrid PU-AC aerogels prepared from acrylate functional “star” monomers. The monomers are made by reacting a tris(isocyanatoaryl)methane with one or more hydroxyacrylates in a suitable solvent.  The monomer is then radically polymerized and the resulting ‘wet’ gel is supercritically dried into an aerogel. In the examples tris(4-isocyanatophenyl)methane is reacted with 2-hydroxyethylacrylate in ethyl acetate. The monomer solution is polymerized by heating with a radical initiator and the resulting gel is then dried using acetone and supercritical CO2.  The resulting aerogels have a density ranging from about 135 to 650 kg/m³ with a porosity bewteen 90 and 50% (v/v).  The lower density aerogels are flexible and have a thermal conductivity of about 40 mW/m.K.

Star monomer according to the invention