*3.5. Surface Wettability*

Dynamic contact angle was used to evaluate the wetting properties of the treated fabrics. Due to the high hydrophilicity of textiles, it is difficult to evaluate their static contact angles. The time required by the fabric to totally absorb the water droplet was considered. The longer the required time, the lower the sample wettability. Figure 4 shows the wetting times. It is clear that the treated fabric presents a more hydrophilic surface compared to the control fabric. A short wetting time was recorded when the water droplet fully spread on the surface. This result can be explained by the fact that the chitosan (microcapsule wall)-treated fabric presents an important percent in oxygen and more C=O or C–O bonds, which are associated with the hydrophilic property.

**Figure 4.** Water droplets on the surface of (**a**) untreated fabric, and (**b**) treated fabric after 3 s of contact.

#### *3.6. Antibacterial Activity Evaluation*

As shown in Figure 5, the extracted oils showed a remarkable antimicrobial activity. They were effective against both *E.coli* and *S.aureus* strains. A clear zone of inhibition was detected. Average distance of peripheral inhibition zone (clear zone around the disc) was measured (Table 2). An additive effect was observed when testing the activity of the oil mixture. The combined effect was greater than individual effects.

**Figure 5.** Antibacterial activity of essential oils in solution using agar diffusion method. A: cloves oil, B: cinnamon oil and C: oil mixture ((**a**): *S.aureus*/(**b**): *E.coli*).


**Table 2.** Peripheral inhibition zones values (mm).

±Standard deviation.

Figure 6 shows that untreated samples did not present any activity since they did not show an inhibition zone around the sample.

Antibacterial activity was detected for individual oil and the mixture. A slight difference was seen between samples against the same bacteria strain and the same sample against the two bacteria strains.

The antibacterial effect exhibited by the microcapsules is predominantly due to the encapsulated essential oils during their release through the microcapsule wall and not from the chitosan itself. It is well known that chitosan is an antibacterial agen<sup>t</sup> [23,24]. However, during the grafting of microcapsules onto cotton fibers, most of the positive amino groups of chitosan were complexed with negative carboxylic groups of the crosslinking agent.

Cinnamon and clove oils affect the envelope structure of Gram-positive and Gramnegative bacteria. The major antibacterial agents of these oils penetrate through the bacteria cell wall and damage the cytoplasmic membrane [25,26].

**Figure 6.** Antibacterial activity results of the (**a**) untreated cotton, (**b**) cotton grafted with clove oil microcapsules, (**c**) cotton grafted with cinnamon oil microcapsules and (**d**) cotton grafted with oil mixture microcapsules.

Comparing results of the inhibition obtained from the clear zones, indifference was observed when using the oil mixture. There was no interaction between one another. The combined effect was the same as when the two oils were individually applied.

Cinnamon oil exhibits good antibacterial activity. However, it is known to be an irritant oil. Combination of cinnamon oil with clove oil can avoid irritant and contact allergy reactions by using lower concentrations of the irritant oil while conserving its important activity against bacteria.
