Pre-Dispersed Organo-Montmorillonite Nano Filler: Morphology, Cytocompatibility and Impact on Flexibility, Toughness and Biostability of Biomedical Ethyl Vinyl Acetate Copolymer

Nano fillers are used to improve the performance of biomedical plastic, nanoclay a common nano filler are used as reinforcing material in polymer due to its ability to enhance strength, toughness, durability and barrier properties of the host polymer and still maintain its lightweight, flexibility, and clarity.

Obtaining a fully exfoliated and dispersion nanoclay is very challenging due to intrinsic incompatibility of the hydrophilic-layered clays and the hydrophobic engineering polymers. In overcoming this, the team introduced pre-dispersing procedure of the organically modified montmorillonite clay organo- montmorillonite, and they were successful.  To improve the quality of nanofiller exfoliation and dispersion, Azlin Osman and colleagues developed a flexible, tough and biostable biomedical ethyl vinyl acetate nanocomposite without the use of non-biomedical friendly additives such as plasticizer. Their recent work is now published in the journal Materials Science and Engineering.

The pre-dispersing process was carried out to obtain enhancement in flexibility, toughness, thermal stability and biostability of the ethyl vinyl acetate nanocomposite, as a new candidate for biomedical plastic. The exfoliation strategy of the organo- montmorillonite was investigated using two different types of dispersing method, that is magnetic stirring and ultrasonication. The authors used X-ray diffraction to examine the morphology of the nanofillers and nanocomposites. Tensile test was performed to evaluate the flexibility, modulus of elasticity, tensile toughness and strength of all the materials.

The pre-dispersing process of both ultrasonic and magnetic stirring methods was observed to slightly alter the diffraction intensity and shoulder shape of the organo- montmorillonite. The stirring using water medium produced better dispersed organo- montmorillonite. The researchers’ XRD and FTIR results, shows that the ultrasonication process using water medium is the most efficient method to disperse the organo- montmorillonite in the ethyl vinyl acetate copolymer.

Their studies proved that the addition of the pre-dispersed organo- montmorillonites (MMT(TL)_mg, MMT(W)_mg and MMT(W)2m_ut) into the ethyl vinyl acetate structure can retain the tensile strength of the copolymer. Moreover in the study,  MMT(W)2m_ut was the best nano filler to enhance the flexibility and toughness of the ethyl vinyl acetate as it showed the greatest efficiency to disperse and interact with the ethyl vinyl acetate copolymer. Furthermore, the cytocompatibility level of the MMT(W)2m_ut nanofiller was also improved as compared to its pristine state (non-pre-dispersed), increasing its potential for implant application.

The MMT(W)2m_ut nano filler and its respective nanocomposite possessed improved  exfoliation and dispersion of the organo- montmorillonite upon the pre-dispersing procedure resulting in an enhanced interactions with the ethyl vinyl acetate copolymer chains, thereby producing a more homogenous ethyl vinyl acetate nanocomposite system.