Browsing by Author "Freixa, Zoraida"
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Item Bringing non-isocyanate polyurethanes closer to industrial implementation using carbonated soybean oil-based amino hardeners(2023-12) Centeno-Pedrazo, Ander; Freixa, Zoraida; Feola, Roland; Lunzer, Florian; Garcia-Suarez, Eduardo J.; Ortiz, Pablo; Tecnalia Research & Innovation; BIOECONOMÍA Y CO2The polyaddition between cyclic carbonates and diamines to form non-isocyanate polyurethanes (NIPUs) is a safer alternative than traditional PU synthesis. However, the lower reactivity of cyclic carbonates requires of long reaction times and/or high temperatures for their curing, hampering their industrial implementation in the coating industry. Starting from carbonated soybean oil (CSBO) and amine excess, and through a stepwise addition process, cyclic carbonate full conversion has been achieved, yielding amino-terminal NIPUs with up to 62 % of biobased content. These amino-terminal NIPUs act as regular amino hardeners, and have been used to cure epoxy resins under the time and temperature required by the coating industry. The performance of these partially bio-based, NIPU-epoxy hybrid coatings was evaluated by pot-life, drying, hardness and solvent resistance, achieving comparable results to the industrial formulations. The simple synthesis process, the suitable curing conditions and the properties of the coatings, bring NIPU chemistry closer to industrial implementation.Item Catalytic Systems for the Effective Fixation of CO2 into Epoxidized Vegetable Oils and Derivates to Obtain Biobased Cyclic Carbonates as Precursors for Greener Polymers(2023-03-01) Centeno-Pedrazo, Ander; Perez-Arce, Jonatan; Freixa, Zoraida; Ortiz, Pablo; Garcia-Suarez, Eduardo J.; Tecnalia Research & Innovation; BIOECONOMÍA Y CO2The chemical fixation of carbon dioxide by cycloaddition to biobased epoxides, e.g., vegetable oils, fatty acids, etc., is an efficient, sustainable, and clean strategy to obtain biobased cyclic carbonates. These can be used as feedstocks for the synthesis of environmentally friendly biobased polymers as an alternative to polymers used in daily life such as polyurethanes (PUs) and/or polycarbonates (PCs). Nevertheless, this reaction is not trivial at all due to both the low reactivity of the CO2 molecule and the nature of the needed substrates (biobased epoxides) where the epoxide groups are internal and sterically hindered, hampering the CO2 cycloaddition reaction. Therefore, the design of efficient catalytic systems to overcome these hurdles is mandatory. Most of the catalytic systems developed for this transformation aim to facilitate the rate-determining step in the CO2 cycloaddition catalytic cycle. They comprise an ionic liquid or an ionic compound with a nucleophilic anion alone or in the presence of a cocatalyst to assist the epoxide ring-opening. The most commonly used catalyst is tetrabutylammonium bromide [TBA][Br] ionic liquid, but other ammonium-, phosphonium-, and sulfonium-based ionic liquids in combination or not with a cocatalyst have also been disclosed in the literature. This Review presents a structured overview of the reported catalytic systems, both homogeneous and heterogeneous catalysts, employed in the transformation of any epoxidized vegetable oil or derivates into biobased carbonated materials. The different catalytic systems have been discussed and compared in terms of catalytic performance, employed substrates, and reaction conditions.