Polyurethane-silica hybrid foam by sol–gel approach: Chemical and functional properties

• Published in: Polymer (Guilford) Vol. 56; pp. 20 - 28
• Main Authors: Verdolotti, Letizia, Lavorgna, Marino, Lamanna, Raffaele, Di Maio, Ernesto, Iannace, Salvatore
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2015
• Subjects: Foaming; Formations; Heat transfer; Hybrid polyurethane foams; Morphology; Plastic foam; Polysiloxane domains; Polyurethane foam; Polyurethane resins; Sol gel process; Thermal conductivity; Thermal conductivity; Polysiloxane domains; Hybrid polyurethane foams
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2014.10.017

Hybrid foams based on polyurethane and polysiloxane-domains were designed in terms of chemical structure and hierarchical morphology to improve the thermal insulation capability of conventional polyurethane foams. Polysiloxane-domains by sol–gel approach reacted with polyols to produce a polysiloxane-reactive-adduct, which completed its formation into polysiloxane aerogel-like structure during the polyurethane foaming process. Hybrids with 5wt% of the polysiloxane-domains exhibited a 22% reduction in thermal conductivity in comparison with pristine PUR. The chemical structure and the hierarchical morphology were studied by means of SAXS/WAXS and 29Si and 13C NMR. In particular the hybrid structure consisted of coarse polysiloxane-fractal-aggregates composed of silica nanoparticles embedded in the polyurethane matrix. Morphological analysis revealed a decrease of the cell size with the increase of the siloxane content ascribed to the nucleation effect of polysiloxane-domains during the foaming. The cell size reduction and the formation of hybrid-aerogel-like structures within the cell-walls are considered the key factors to reduce the thermal conductivity of hybrid foams. [Display omitted]