Preparation and characterization of novel clay/scleroglucan nanocomposites

• Novel nanocomposites were prepared using the polymer scleroglucan.
• Bentonite from Porto Santo Island and reference clay SWy-2 were used as fillers.
• Morphology and thermal stability of the two nanocomposites were compared.
• A mixed morphology and an enhanced thermal stability were achieved in both cases.
• Results indicate the untapped potential present in global deposits of clay.

In pursuit of integrating the use of clay/polymer nanocomposites (CPN) into mainstream applications, improvements made to the preparation process can be useful measures. One such measure involves taking advantage of the global prevalence of clay deposits via their use as primary sources for filler material, as opposed to expensive reference or commercial clay minerals. In this paper, a novel CPN was prepared using bentonite from Porto Santo Island, located in the Madeira archipelago, and was subsequently compared to a CPN prepared using the reference clay mineral SWy-2. According to an XRD characterization of both of the CPN materials, a monolayer intercalation of the biopolymer between the clay mineral layers had occurred. TEM results indicated that there was a mixture of exfoliated and intercalated structures in both cases, but in that of the CPN prepared using Porto Santo bentonite, a greater extent of disorder was observed. This was interpreted as having implications in the thermal stability of the CPN, since that of Porto Santo bentonite outperformed the SWy-2 based CPN when the temperatures of the 60% mass loss were compared. Nonetheless, TGA analysis of both nanocomposites indicated a thermal stability that surpassed that of the pristine polymer alone. This advantageous feature, in conjunction with the low-cost and high accessibility of filler material sourced directly from natural clay deposits, is a promising aspect towards improving the applicability of clay polymer nanocomposites.