Microencapsulation of Melaleuca alternifolia (Tea Tree) Oil as Biocide for Footwear Applications

Abstract

Functional materials with antimicrobial properties are being investigated in order to provide shoes with new properties and added value by incorporating natural antimicrobial agents to conventional materials (leather, fabrics, foams, etc). Microencapsulation is an effective method to protect these functional natural biocides from reactions with moisture, light, and oxygen. If a footwear material is treated with microencapsulated biocide agents, higher durability of functionality is expected. This article reports the evaluation of Melaleuca alternifolia (tea tree) oil which is a natural essential oil, as an antimicrobial agent for footwear application. Furthermore, microcapsules containing this essential oil were synthesized by in situ polymerization method using a melamine-formaldehyde resin as shell material in order to increase the durability of this natural biocide in footwear materials. Microcapsule characterization, such as particle size, morphology, and chemical properties was carried out for different oil to polymer ratios. Finally, the incorporation of the microencapsulated biocides into different footwear materials was also evaluated.

Keywords:

• Antimicrobial activity
• melamine-formaldehyde
• O/W emulsions
• Staphylococcus aureus
• tea tree oil (TTO)

Acknowledgments

This work was partially funded by the Institute of Small and Medium Industry of the Generalitat Valenciana (IMPIVA), through the project IMIDIC/2010/106.

Notes

^a ISO 4730, International Organization for Standardization standard no. 4730. International Organization for Standardization. 2004. ISO 4730:2004. Oil of Melaleuca, terpinen-4-ol type (tea tree oil). International Organization for Standardization.

^b From ref. 9.

^c No upper limit is set, although 48% has been proposed.

^d No lower limit is set.

(−): no antimicrobial activity observed.

(++): moderate antimicrobial activity observed.

(+++): strong antimicrobial activity observed.

From the Proceedings from Formula VI in Stockholm 2010.