Browsing by Subject "Thiol-epoxy reaction"

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Open Access
In situ preparation of thermoset/clay nanocomposites via thiol-epoxy click chemistry
(Springer Verlag, 2018) Purut, Koc, O.; Bekin, Acar, S.; Uyar, Tamer; Tasdelen, M. A.
A series of thermoset/clay nanocomposites are prepared by thiol-epoxy click reaction using commercially available starting compounds at ambient conditions in very good yields. The incorporation and exfoliation of clay nanolayers in the thermoset matrix are confirmed by FT-IR, XRD and TEM analyses. The influence of clay loadings on the thermal and mechanical analyses is investigated and all nanocomposites exhibit improved properties than that of the pristine thermoset. The nanocomposite containing 1% montmorillonite by weight has the most improved mechanical properties due to its highly exfoliated structure resulting in efficient interactions between clay and polymer matrix. A further increase of the clay loading results in the aggregation of clay plates to form intercalated structures leading to deteriorated thermal and mechanical properties of nanocomposites.
Open Access
Polyhedral oligomeric silsesquioxane-based hybrid networks obtained via thiol-epoxy click chemistry
(Springer, 2017) Bekin Acar, S.; Ozcelik, M.; Uyar, Tamer; Tasdelen, M. A.
A series of hybrid networks based on polyhedral oligomeric silsesquioxane (POSS) were prepared by thiol-epoxy click reaction using commercially available octakis-glycidyl-POSS (G-POSS), trimethylolpropane triglycidyl ether, and trimethylolpropane tris(3-mercaptopropionate) as monomers. The click reaction was simply catalyzed by lithium hydroxide which proceeded readily at ambient conditions in very good yields. The incorporation of G-POSS into the network was clearly determined by transmission electron microscopy, FTIR, and 1H-NMR spectroscopy techniques performed with a model study using 1-butane thiol and G-POSS molecules. The homogeneous distribution of G-POSS up to 5 wt% in the hybrid network was apparently confirmed by morphological investigations. By increasing G-POSS content higher than 5 wt%, the heterogeneous dispersion of G-POSS was determined from the tensile strength measurements. The significant decrease in tensile strength was possible due to the agglomeration of G-POSS. On the other hand, thermal properties of hybrid networks were compared together by thermogravimetric analyses, where all samples exhibited one-step degradation in the range of 220–500 °C. The thermal decomposition of hybrid network led to complete degradation of the organic part and favored the formation of stable carbonaceous and inorganic residues as char. Thus, the char yields of hybrid networks were increased to 6.2, 7.8, 10.1, 12.7, and 15.1% by G-POSS loadings from 0 to 15 wt%. This improvement was also a proof of the incorporation of G-POSS into the hybrid networks that resulted in high heat-resistant POSS-based hybrid networks compared to a sample without G-POSS.