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Nowadays, there is huge demand for novel materials which are desired for new functions and new technological advancements. All technological demands for new applications cannot be implemented by many of the well-established materials, such as single plastics, metals or ceramics. Hence, engineers and scientists realized that, in comparison with pristine counterparts of material, the mixtures of materials can produce much better properties. Polymer nanocomposites is a new form of materials that resulted by the combination of polymers and nanofillers which contributed to various benefits over the neat polymer such as improvement in biocompatibility, biostability, thermal stability, flame retardancy, mechanical and barrier properties. Due to these factors, nanocomposites have received an extraordinary consideration for use in broad range of applications. However, the polymer nanocomposites which comprised of copolymer as matrix material are not widely studied, especially those involved poly(ethylene-co-vinyl acetate) (PEVA). The production of PEVA copolymer-based nanocomposites for various applications has been reported by few research papers. In this communication, a review on the properties of PEVA-based nanocomposites with different types of nanofiller was summarized, revealing the high potential of this class of nanocomposite for advanced applications.

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Poly(ethylene-vinyl acetate) (PEVA) nanocomposite incorporating dual clay nanofiller (DCN) of surface modified montmorillonite (S-MMT) and bentonite (Bent) was studied for biomedical applications. In order to overcome agglomeration of the DCN, the S-MMT and Bent were subjected to a physical treatment prior to being mixed with the copolymer to form nanocomposite material. The S-MMT and Bent were physically treated to become S-MMT(P) and Bent(pH-s), respectively, that could be more readily dispersed in the copolymer matrix due to increments in their basal spacing and loosening of their tactoid structure. The biocompatibility of both nanofillers was assessed through a fibroblast cell cytotoxicity assay. The mechanical properties of the neat PEVA, PEVA nanocomposites, and PEVA-DCN nanocomposites were evaluated using a tensile test for determining the best S-MMT(P):Bent(pH-s) ratio. The results were supported by morphological studies by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Biostability evaluation of the samples was conducted by comparing the ambient tensile test data with the in vitro tensile test data (after being immersed in simulated body fluid at 37 °C for 3 months). The results were supported by surface degradation analysis. Our results indicate that the cytotoxicity level of both nanofillers reduced upon the physical treatment process, making them safe to be used in low concentration as dual nanofillers in the PEVA-DCN nanocomposite. The results of tensile testing, SEM, and TEM proved that the ratio of 4:1 (S-MMT(P):Bent(pH-s)) provides a greater enhancement in the mechanical properties of the PEVA matrix. The biostability assessment indicated that the PEVA-DCN nanocomposite can achieve much better retention in tensile strength after being subjected to the simulated physiological fluid for 3 months with less surface degradation effect. These findings signify the potential of the S-MMT(P)/Bent(pH-s) as a reinforcing DCN, with simultaneous function as biostabilizing agent to the PEVA copolymer for implant application.

Poly (ethylene-co-vinyl acetate) (PEVA) is a biocompatible copolymer, easily processed and designed for intricate biomedical products. However, its toughness; which is the combination of high flexibility and high strength is quite low to resist tearing during long term use in human biological system. In this study, the possibility to enhance the tensile toughness of the PEVA was studied. Several ratios of organically modified MMT and bentonite were used as hybrid nanofillers in the PEVA matrix to form hybrid nanocomposites. Both nanoclays were pre-dispersed and destabilized prior to melt compounding with the PEVA. Results indicated that the use of O-MMT and bentonite in a ratio of 4:1 brought the best increment in the tensile toughness of the PEVA. This could be related to the improved interactions between PEVA with the hybrid nanofillers.