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Bio- and CO2-sourced non-isocyanate polyurethane (NIPU) microcellular foams were prepared using supercritical carbon dioxide (scCO2) foaming technology. These low-density foams offer low thermal conductivity and have an impressive potential for use in insulating materials. They constitute attractive alternatives to conventional polyurethane foams. We investigated CO2's ability to synthesize the cyclic carbonates that are used in the preparation of NIPU by melt step-growth polymerization with a bio-sourced amino-telechelic oligoamide and for NIPU foaming. Our study shows that CO2 is not only sequestered in the material for long-term application, but is also valorized as a blowing agent in the production of NIPU foams. Such foams will contribute to energy conservation and savings by reducing CO2 emissions. [ABSTRACT FROM AUTHOR]

In this paper, a 4-ethylphenol- para -phenylenediamine (4EP- p PDA) benzoxazine has been applied and cured on previously anodized AA2024-T3 substrates. The porous surface oxide layers obtained from sulfo-tartaric anodizing appeared to be highly impregnated by the benzoxazine resin, sealing the anodic films. Through rheological, morphological and chemical characterization, the curing process has been identified to be the key step for the impregnation to occur, related to the low viscosity of the 4EP- p PDA benzoxazine attained during thermal curing. Moreover, the typical surface porosity of the anodic layer reappeared after curing, offering a good anchoring to possible top coats. Finally, high and enduring barrier properties of this hybrid organic-inorganic layer have been highlighted through Electrochemical Impedance Spectroscopy (EIS) and correlated with recent results obtained by Molecular Dynamics Simulations (MDS). These barrier properties appeared to be strongly influenced by the curing process parameters, as has been assessed using alternative curing cycles limiting their duration and lowering the curing temperature. Consequently, adapting the curing process enables the optimization of the barrier properties of the system while respecting the dependence of the mechanical properties of the AA2024-T3 substrate on thermal treatment at high temperatures., Competing Interests: There are no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

Untreated multi-walled carbon nanotubes (MWCNTs) have been dispersed in two benzoxazine precursors following an easy procedure. The strong intrinsic interactions of CNTs with a selected precursor give rise to the formation of a reinforced network with outstanding thermo-mechanical properties.