Abstract
High oleic sunflower oil-based polyol was obtained by thiol-ene coupling and applied in the preparation of flexible polyurethane foams. The photochemically initiated thiol-ene click reaction was carried out under UV irradiation using 2-mercaptoethanol. Bio-based polyol with hydroxyl value of 201.4 mg KOH/g was used as 30 wt% substituent of petrochemical polyether polyol in the formulations of flexible foams. Both reference foams, as well as foams modified with bio-based polyol, were formulated to have various isocyanate indices (0.85, 0.95, 1.05). Flexible foams were compared in terms of their thermomechanical properties and analyzed using FT-IR and SEM microscopy. Modification with bio-based polyol resulted in foams with superior compression properties, higher support factor, and lower resilience than reference foams. TGA and FT-IR curves confirmed the presence of urethane/urea and ether linkages in the polyurethane matrix. Moreover, double glass transition temperature corresponding to soft and hard segments of polyurethane was observed by DSC proving the phase-separated morphology.
Highlights
Development of bio-based polymers is connected with looking for green, low cost and environmentally friendly raw materials
The first part relates to the synthesis of HOSObased polyol, while the second one deals with the application of obtained polyol in the preparation of flexible polyurethane foams
HOSO was thoroughly characterized before its application in the thiol-ene reaction of bio-based polyol synthesis
Summary
Development of bio-based polymers is connected with looking for green, low cost and environmentally friendly raw materials. Following the concept of sustainable development, scientific research is focused on finding new bio-based monomers to replace petroleum-based ones [1,2,3,4]. It can be achieved by e.g., thiol-ene addition (or thiol-ene click reaction) of thiols to the double bonds of organic compounds. This clickchemistry reaction [5] follows the Green Chemistry principles [6,7] and is important in obtaining bio-based monomers since numerous renewable sources, such as vegetable oils or terpenes, have C=C double bonds [8]. Thiol-ene reaction is carried out under mild conditions and characterized with high yield, high reaction rates, and absence of byproducts if an equimolecular ratio of thiol groups to double bonds is used [12,15,16,17]
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