**Acknowledgements**

*Advanced Supercritical Fluids Technologies*

fabricate antibacterial dental floss, and inhibition of more than 99.99% has been achieved [42]. Recently, Pajnik and co-workers impregnated pyrethrum extract to polypropylene, polyamide, and cellulose acetate in the form of films and beads using scCO2 to fabricate functionalized materials with repellent properties [43]. In addition, chitosan and derivatives have been used to impregnate polyester in scCO2 bath [44]. Results showed that low molecular weight chitosan and chitosan lactic acid salt were successfully impregnated whereas no chitin could be impregnated. More recently, very low molecular weight chitosan and chitosan lactate have also been successfully incorporated to polyester fabric using scCO2 dyeing technique in our research group obtaining good antibacterial activity [45]. Overall, naturalbased functional agents have shown a huge potential for the fabrication of various

In addition to the agents mentioned above, impregnation of organometallic compounds into polymer matrices using scCO2 has also been widely studied for various functional applications. Antifungal textiles have been produced via scCO2 impregnation of cotton with silver, Ag (hepta), and Ag (cod), demonstrating measurable inhibition [46]. Boggess et al. produced highly reflective polyimide films for aerospace application with silver-containing additive using scCO2 infusion and subsequent curing at 300°C [47]. They have demonstrated that silver additive was incorporated into a polyimide film creating a reflective surface on both sides of the film. Chiu et al*.* [48] produced a wearable photocatalytic device via integration of Ni-P/TiO2 onto silk fabric using scCO2 impregnation technique. Co-deposition of photocatalytic TiO2 and electrically conductive Ni-P metallization layer was achieved through scCO2-assisted electroless plating and silk fabric with higher corrosion-resistant, and photocatalytic activity was achieved. Metallization of silk with platinum (Pt) was also conducted in scCO2 medium obtaining a smooth and compact layer with improved adhesion promoted by sccCO2 metallization [49]. The results demonstrated its applicability in medical and wearable devices. Cotton fabric has been impregnated with palladium (II) hexafluoroacetylacetonate to fabricate conductive fabrics [50]. Hematite nanoparticles were loaded to cellulosic fiber under scCO2 to fabricate a water repellent composite fiber [51]. Peng et al. used silver nanoparticles to coat wool fabrics in scCO2, and the coated fabric exhibited excellent catalytic, antistatic, and antibacterial activities [52]. Polycarbonate has been impregnated with silver nitrate in scCO2, resulting up to 99.9% bacteria reduction [53]. Belmas and co-workers [54–56] have used scCO2 process to impregnate a range of organometallic complexes in a synthetic polymer prior to electroless copper plating to improve the adhesion of copper to the polymer. The adhesion between the copper and polymer was much improved after scCO2 impregnation of the organometallic complexes. Polyacrylate has been impregnated with copper (II) hexafluoroacetylacetonate in scCO2 followed by thermal decomposition of the copper. The formation of copper oxide was evident ensuring improved wear resistance of polyacrylate [57]. In conclusion, owing to nanoscale metal microparticles, organometallic compounds have been successfully used to modify polymers in scCO2 solvent for various functional applications and might be one potential area that needs further investigations in the future.

From the studies reviewed in this chapter, it has been shown that scCO2 is a viable technique for the fabrication of various functional materials if appropriate

functional materials using scCO2 impregnation technique.

**4.4 Organometallic-based functional agents**

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**5. Conclusions**

All the universities collaborating on the program are gratefully acknowledged.
