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Front Cover: In article number 2000197 by Mustapha Raihane, Mehmet Atilla Tasdelen, and co‐workers, thermoset nanocomposites containing methacrylated halloysite nanotubes are prepared by in situ free radical photocrosslinking polymerization using multifunctional methacrylates. The chemical attachment of halloysite nanotubes not only improve tensile strength and elasticity modulus of the obtained nanocomposites, but also enhance their thermal properties.

Naturally occurring halloysite nanotubes (HNTs) are first functionalized by 3‐(trimethoxysilyl) propyl methacrylate and then used as nanofillers in a mixture of difunctional methacrylates (triethylene glycol dimethacrylate and bisphenol A glycerolate dimethacrylate). Upon free radical photocrosslinking of this mixture enables the in situ preparation of HNT/thermoset nanocomposites. The covalent bonding of HNT in the thermoset matrix is proven by following characteristic bands of the mixture using Fourier transformed infrared spectroscopy. Furthermore, the presence and distribution of HNT in the nanocomposites are confirmed by scanning electron microscopy with energy dispersive X‐ray spectroscopy, and transmission electron microscopy observations. In addition, a mixed morphology containing agglomerated/nonagglomerated HNTs in the thermoset matrix is also determined. Both tensile strength and elasticity modulus of nanocomposites are dramatically increased with increase in HNT loading up to 4% ratio. On the other hand, these nanocomposites exhibit higher thermal properties compared to the neat thermoset.

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.

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